Disclosure: The authors declared no conflict of interest. See the online ICMJE Conflict of Interest Forms for this article.
A pilot randomized controlled trial of a commercial diet and exercise weight loss program in minority breast cancer survivors†
Article first published online: 16 MAR 2013
Copyright © 2013 The Obesity Society
Volume 21, Issue 1, pages 65–76, January 2013
How to Cite
Greenlee, H. A., Crew, K. D., Mata, J. M., McKinley, P. S., Rundle, A. G., Zhang, W., Liao, Y., Tsai, W. Y. and Hershman, D. L. (2013), A pilot randomized controlled trial of a commercial diet and exercise weight loss program in minority breast cancer survivors. Obesity, 21: 65–76. doi: 10.1002/oby.20245
- Issue published online: 16 MAR 2013
- Article first published online: 16 MAR 2013
- Manuscript Accepted: 21 MAY 2012
- Manuscript Received: 7 JUL 2011
Obesity is associated with poorer breast cancer outcomes and losing weight postdiagnosis may improve survival. As Hispanic and black women have poorer breast cancer prognosis than non-Hispanic whites diagnosed at similar age and stage, and have higher rates of obesity, effective weight loss strategies are needed. We piloted a randomized, waitlist-controlled, crossover study to examine the effects and feasibility of the commercial Curves weight loss program among Hispanic, African American and Afro-Caribbean breast cancer survivors.
Design and Methods:
Women with stage 0–IIIa breast cancer ≥6 months posttreatment, sedentary, and BMI ≥25 kg/m2 were randomized to the immediate arm (IA): 6 months of the Curves program followed by 6 months of observation; or the waitlist control arm (WCA): 6 months of observation followed by 6 months of the Curves program. The Curves program uses a 30-min exercise circuit and a high-vegetable/low-fat/calorie-restricted diet.
A total of 42 women enrolled (79% Hispanic, 21% black), mean age 51 (range 32–69) and mean BMI 33.2(±5.9) kg/m2; 91% were retained at month 12. At month 6, women in the IA lost an average 3.3% (±3.5%) of body weight (range: 1.7% gain to 10.6% loss), as compared with 1.8% (±2.9%) weight loss in the WCA (P = 0.04). At month 12, on average women in the IA regained some but not all of the weight lost during the first 6 months (P = 0.02).
Minority breast cancer survivors were recruited and retained in a weight loss study. Six months of the Curves program resulted in moderate weight loss, but weight loss was not maintained postintervention. Future interventions should identify methods to increase uptake and maintenance of weight loss behaviors.
There are currently over 2.5 million breast cancer survivors, an estimated 64% of whom are overweight (BMI 25–30 kg/m2) or obese (BMI >30 kg/m2) (1,2). Obesity is associated with metabolic and hormonal profiles that may stimulate BC growth (3,4) and obesity at the time of diagnosis has been associated with decreased breast cancer survival (5). Many women gain a substantial amount of weight during BC treatment and few return to their prediagnosis weight (6). Observational studies have suggested that lean body mass and regular exercise after a breast cancer diagnosis may improve breast cancer survival, though it is unknown if weight loss among overweight and obese women with breast cancer will improve survival (3,4,5,7). Studies of the effect of dietary change after diagnosis on survival have yielded conflicting results (8,9). The optimal post-breast cancer diagnosis diet, exercise regimen, and body size have yet to be identified, and may differ by population.
Breast cancer incidence rates and prognosis differ by race/ethnicity. In the US, non-Hispanic white women have higher breast cancer incidence rates when compared with African American and Hispanic women (1). However, Hispanic and black breast cancer survivors have poorer prognosis than non-Hispanic whites when diagnosed at similar age and stage (10,11). When compared with non-Hispanic whites, Hispanic women and black women (both African American and Afro-Caribbean) have lifestyle patterns that may contribute to their poorer breast cancer survival. When compared with non-Hispanic whites, Hispanic and black women have higher rates of obesity (21.8%, compared with 29.4% and 39.2%, respectively), lower rates of meeting physical activity guidelines (19.0%, compared with 12.5% and 17.5%, respectively), and lower intake of three or more servings of fruits and vegetables per day (27.7%, compared with 19.7% and 21.9%, respectively) (12,13,14). Many Hispanic and black women who live in densely populated urban areas, such as New York City, have limited access to healthy foods and leisure time physical activity due to lack of financial and community resources (15,16). Low-income minority breast cancer survivors may benefit from a weight loss intervention that is financially affordable and easily accessible in their communities.
To reduce recurrence risk and to improve survival, current cancer prevention guidelines for cancer survivors recommend engaging in 30–60 min of moderate-vigorous physical activity 5–7 days per week, eating a diet high in fruits and vegetables, and maintaining a BMI less than 25 kg/m2 (17,18). Many studies have examined the ability and effects of various dietary and physical activity interventions to change lifestyle behaviors among breast cancer survivors (19,20), including a growing body of literature specifically examining various approaches to weight loss (20). To date, there is a very limited literature on lifestyle modification and weight loss studies specifically targeting Hispanic and African American breast cancer survivors (21,22,23). There is a need to identify comprehensive interventions targeting diet, physical activity, and body size that are translatable to the real world setting, sustainable over time, and culturally appropriate and accessible to minority populations.
We conducted a pilot and feasibility study to examine the effects of the commercial Curves weight loss program among urban, Hispanic, and black breast cancer survivors, which are the two predominant minority patient populations at our academic medical center. Curves is a large fitness chain in the United States and centers are located throughout many areas of the United States, including urban areas that are ethnically diverse. Membership fees are priced at ∼$50/month. The Curves Weight Management Program promotes weight loss through physical activity at their centers and dietary change using a standardized program. The dietary change program is taught to members via a 6-week nutrition course led by Curves staff using a book, DVDs, and an instructor's manual.
The La Vida Activa/An Active Life study was a randomized, crossover, waitlist-controlled pilot and feasibility study to test the effects of 6 months of the Curves weight loss program among Hispanic and black breast cancer survivors. The primary aims of this pilot study were to assess whether this community-situated approach to weight loss was acceptable to Hispanic and black breast cancer survivors and if the program resulted in clinically meaningful weight loss after 6 months. An additional 6 months of follow-up allowed us to observe whether women in the immediate arm were able to maintain and/or continue their weight loss after the active intervention period, as well as allow data collection on the effects of the intervention in the waitlist control group. We hypothesized that this moderately priced, community-situated, standardized weight loss program would appeal to urban minority breast cancer survivors. Here, we report the main study outcomes, including feasibility, adherence, weight loss, and changes in metabolic biomarkers.
Methods and Procedures
Women were recruited from the Columbia University Medical Center (CUMC) breast oncology clinic. Potentially eligible women were referred by their breast oncologists to be screened by study staff for the following eligibility criteria: age 21–70 years; self-identified as Hispanic or of African descent (African American or Caribbean); diagnosis of stage 0–IIIa breast cancer; completed surgery, chemotherapy, and radiation therapy at least 6 months prior; no evidence of recurrent or metastatic disease; BMI >25 kg/m2; sedentary (defined as physically active to the point of sweating <20 min per week); not actively engaged in a weight loss program; nonsmoker; hemoglobin A1c <8%; blood pressure <140/90; and low-density lipoprotein cholesterol <150 mg/dl. Both pre- and postmenopausal women were included in this pilot study to explore the feasibility aspect of the study in both populations. Smokers were excluded because investigators held it was more important to engage these women in a smoking cessation program than a weight loss program. Women with uncontrolled diabetes, hypertension, and hypercholesterolemia were excluded from the study as a precaution to avoid exacerbation of underlying cardiac and/or metabolic conditions in an intervention that was in the early testing phase. Breast cancer diagnosis and treatment and all clinical measures were confirmed by medical record review.
The study was designed to be targeted toward Hispanic and black women living within New York City. All study activities and materials were offered in Spanish and English. The study staff was fully bilingual. The study was approved by the CUMC IRB and all participants provided written informed consent.
Eligible participants were scheduled for a baseline visit where they completed the following procedures: fasting morning blood draw; interview on demographic characteristics, medical history, health habits, and physical activity; food frequency questionnaire; physical examination assessing blood pressure, resting heart rate, and anthropometric measures; dual energy X-ray absorptiometry (DEXA); and cardiopulmonary exercise stress test. All participants received written physician clearance for exercise, dietary change, and weight loss.
Eligible participants were randomized to one of two study arms via randomly permuted blocks. In the immediate arm, participants received 6 months of the Curves weight loss program, followed by 6 months of observation during which they could engage in any diet and physical activity of their choice. In the waitlist control arm, participants were observed for 6 months during which they were asked not to change their physical activity or diet, followed by 6 months of the Curves program. In order to allow women randomized into the immediate arm to initiate participation in the nutrition courses as part of a group, randomization occurred at five different time points throughout the course of the study.
The study made use of the Curves Weight Management Program curriculum, which at the time of the study was widely available to the public. The Curves program included use of the Curves fitness centers and a Curves diet plan, which was taught by Curves staff via a standardized nutrition course that made use of a book, DVDs, and an instructor's manual all published by Curves. At the time of the study, based on company policy, Curves fitness centers had the option of offering the group nutrition course to their members at their discretion. Many of the participating Curves centers did not offer the nutrition course on a regular basis. In order to ensure that all study participants across New York City could have access to the nutrition course, two Curves fitness center owners conducted the nutrition courses at the CUMC for study participants.
Exercise. During the 6-month intervention period, participants were provided with memberships to a Curves fitness center that was convenient to their home and/or workplace. The study had a target goal for women to exercise at the fitness centers 3 days/week. Women were told by study staff that the target was for women to exercise 5 days/week; this “reach goal” approach was used because it was expected that women would attend the fitness center on a fewer number of days than the stated goal. The Curves circuit-based exercise program alternates 30 s of bi-directional, strength-training pneumatic resistance machine exercises prescribed at an individual intensity with 30 s of low-impact aerobic activity. An exercise session includes 25 min of the circuit followed by 5 min of cool down and stretching. At the beginning of their exercise program, subjects met individually with a Curves trainer to receive three one-on-one training sessions. The training program began with 15-min sessions targeting ≤60% of the individual's maximal heart rate, and by week 8 gradually increased to 30-min sessions while maintaining 70–75% of maximal heart rate. The program is a moderate-intensity workout, based on targeted heart rate (24).
Safety. New York State law required that all fitness center staff be CPR certified. All fitness centers had at least one Curves certified circuit trainer, and all staff received verbal and written instructions on how to work with study participants. Participants were provided Polar S-610 heart rate monitors, (Polar Electro Oy, Finland) along with verbal and written instructions on their use, to monitor and record heart rate during all exercise sessions. A study physician was always on-call to handle any urgent medical issues. Participants self-reported any adverse events during study follow-ups.
Dietary change. The dietary change component of the program began ∼1 month after beginning the exercise program. Participants attended a nutrition course that consisted of six 1-h weekly group sessions over 6 consecutive weeks taught by a bilingual instructor at the CUMC. Each session involved a 15–20 min DVD presentation, a 15–20 min lecture based on an instructor's manual, and 20 min of discussion. Session topics included setting weight loss goals, dietary recommendations, food shopping, eating out, understanding energy balance, the Curves workout, and troubleshooting barriers to adhering to the weight loss program. During the sessions, the following daily behaviors were encouraged: eat breakfast, eat five small meals, eat ≥2 servings fruit, eat ≥3 servings vegetables, drink 2 l of water, read food labels when choosing foods, and pay attention to intake of total calories, protein, fat, and carbohydrates. Participants were provided with a Curves weight loss program instruction and recipe book (25). General guidelines were to reduce caloric intake (1,200 cal/day for 1 to 2 weeks, followed by 1,600 cal/day) and to distribute calorie intake as 45% protein/30% carbohydrates/25% fat. During the 6-week period, participants received weekly motivational telephone calls from the instructor and participants were allowed to make-up missed sessions by phone or in person. Participants were given the choice of enrolling in a nutrition course that was taught in English or in Spanish; courses were scheduled once enough participants had been enrolled to fill a course. During the study, a total of eight nutrition courses were offered, six in Spanish and two in English. More courses were offered in Spanish than in English due to participant preference. Study participants and fitness center staff were advised that study participants were not permitted to use protein powders or dietary supplements sold by Curves as the effects of these are not known in breast cancer survivors.
Follow-up data collection
At 3-, 6-, 9-, and 12-month follow-up clinic visits, blood pressure, resting heart rate, and anthropometric measures were measured and participants answered questions about dietary and physical activity patterns. At 6 months, participants underwent DEXA and cardiopulmonary exercise testing. At 6 and 12 months, participants provided fasting morning blood samples and completed a food frequency questionnaire. Each month, participants were contacted by phone to answer questions about exercise and dietary behaviors and to promote study retention.
Anthropometric measures. Weight and height were measured using a calibrated electronic scale (SR Instruments, Tonowanda, NY) and stadiometer (Genentech Accustat, San Francisco, CA). Waist and hip circumferences were measured by trained study staff using a Gulick II tape measure (Country Technology, Gays Mills, WI).
DEXA and body composition. Body composition was measured by DEXA using the Hologic QDR 4500 densitometer (Hologic, Waltham, MA). Baseline and 6-month measurements used the same densitometer, software, and scan speed.
VO2max. Cardiovascular fitness assessed with a Medical Graphic's CPX-D (Medical Graphics, St. Paul, MN) metabolic cart equipped with Breeze Suite 6.2 software was used for metabolic data collection. Subjects were monitored using a Marquette CASE 8000 Electrocardiogram and exercised on a Marquette Series 2000 treadmill, using GE Medical Systems IT CASE 4.14 software.
Serum metabolic marker analyses. Serum samples were analyzed in batches after all samples were collected. Cholesterol (total, high-density lipoprotein, indirect low-density lipoprotein), triglycerides, glucose, and hsCRP were measured via an Integra 400 Plus automated chemistry analyzer (Roche Diagnostics, Indianapolis, IN). Radioimmunoassays were used to measure insulin (Siemens, Deerfield, IL), total ghrelin (LINCO Research, St. Charles, MO), and adiponectin (Millipore, Billerica, MA). Enzyme-linked immunosorbent assays were used to measure insulin-like growth factor (IGF)-I, total IGF binding protein-1, and IGF binding protein-3 (Diagnostic Systems Laboratories, Webster, TX). Insulin resistance was calculated using the homeostasis model assessment (HOMA-IR) (26).
Physical activity. Physical activity over the previous 3 months was measured via a self-administered adaptation of the Kaiser Physical Activity Survey, which measures type, frequency, duration, and intensity of all forms of physical activity (27). The survey provides four global summary activity indexes (score 1–5; 1 low activity, 5 high activity) of the following physical activity subtypes: housework/caregiving, active living habits, sports/exercise, and occupation.
Diet. Dietary intake was assessed using the Spanish version of the Block Questionnaire, with text in both Spanish and English on each page (28). The original 110-item Block Questionnaire was developed using NHANES dietary recall data, which includes representation of African Americans. The Spanish version of the Block Questionnaire includes additional food items typical of diets among Hispanics.
Intervention adherence. Adherence to the exercise program was monitored using computerized Curves attendance logs. Attendance was recorded at the nutrition education sessions and telephone make-up sessions were tracked.
An adherence index was created to reflect the amount of uptake of the recommended behaviors. At baseline, 6 months and 12 months, participants were asked about the frequency of specific behaviors over the past 7 days. The index has a possible score range from 4–61 and was created by summing scores from the following: engage in recreational physical activity or exercise (1 point per day, 0–7 points possible); eat breakfast, eat five small meals per day, eat ≥2 servings fruit per day, eat ≥3 servings vegetables per day, drink 2 l of water per day (possible points for each: less than or equal to once per week = 1 point, once per week = 2 points, 2 to 3 times per week = 3 points, 4–6 times per week = 4 points, every day = 5 points); eat sugary foods (≤once per week = −1 point, once per week = −2 points, 2 to 3 times per week = −3 points, 4–6 times per week = −4 points, every day = −5 points, more than once a day = −6 points; −1 to −6 points possible); read food labels, pay attention to caloric intake, pay attention to carbohydrate intake, pay attention to protein intake, pay attention to fat intake (possible points for each: less than once per week = 1 point, once per week = 2 points, 2 to 3 times per week = 3 points, 4–6 times per week = 4 points, every day = 5 points, and more than once a day= 6 points).
This pilot study was designed and powered to detect a difference in weight loss between intervention groups at 6 months. Descriptive analyses were performed using two-sample t-tests, paired t-tests, Fisher exact tests and χ2 tests. To examine the effect of the intervention on weight change from baseline to 6 months, we fit a generalized estimating equations (GEE) model with repeated measures nested with participants, using baseline weight and height as the covariates. We included time as a continuous variable and allowed weight outcomes over time to be correlated with an autoregressive structure. We used a similar approach to examine the effect of the intervention on rate of weight change from baseline to 6 months. Amount of weight lost by change in adherence index score was assessed using a linear regression model adjusted for index category (above or below the median change in score at 6 months) and randomization arm.
Exploratory analyses examined the effect of weight loss on change in biomarkers by dichotomizing weight loss into two groups <5% and ≥5% weight loss, and, <2% and ≥2% fat loss as assessed by DEXA, using two-sample t-tests to compare differences in percent change from baseline between groups. These cut points were chosen based on the hypothesized amount of weight loss needed to observe clinically meaningful metabolic effects and so that results could be compared with other recently published weight loss studies (29).
Analyses were conducted using SAS 9.2 (Cary, NC).
Recruitment, retention, and baseline characteristics
Between August 2007 and June 2008, 42 women were randomized into the study; 22 to the immediate arm and 20 to the waitlist control arm (Figure 1). Of these 42 women, 38 (90.5%) were retained in the study for the full 12 months, the 4 women who were removed from the study (n = 2) or dropped out of the study (n = 2) were Hispanic. Seventy-nine percent of participants were Hispanic and 21% were black, 81% were postmenopausal, mean age was 50.7 (±8.9) years and mean time since diagnosis was 4.1 (±2.7) years (Table 1). Fifty-nine percent of postmenopausal women were on hormonal therapy during study participation. On average at baseline, participants had a BMI of 33.2 (±5.9) kg/m2, consumed 2.9 (±1.7) servings of fruits/vegetables per day, and had a VO2max of 18.4 ml/kg/min (±3.6 ml/kg/min), which is categorized as poor cardiorespiratory fitness (30). There were no statistically significant differences in baseline characteristics between Hispanic (n = 33) and black (n = 9) participants (data not shown).
Attendance and adherence
Exercise sessions and physical activity. During the course of the study, participants exercised at nine Curves fitness centers throughout four New York City boroughs. During the intervention periods, participants in the immediate arm and waitlist control arm exercised an average of 1.1 (±0.8) and 0.6 (±0.5) times per week, respectively (data not shown), which was less than the targeted goal of three exercise sessions per week, but was an increase from their baseline levels of physical activity (P = 0.03). The Kaiser Physical Activity Survey assessed changes in all levels of physical activity during the study period (Table 2). After each group completed their intervention period, there was an increase in the global sports/exercise index, which measures participation in all forms of recreational physical activity, sports and exercise. There was no evidence of change in the active living index or household/caregiving index in either group during the study period.
Nutrition courses and dietary change. Dietary adherence and change were assessed by attendance at nutrition courses, change in diet as assessed by food frequency questionnaire, and change in dietary behaviors. All women participated in the nutrition course, with average in-person attendance of 5.1 (±0.9) and 5.0 (±1.3) sessions (of a total of six possible sessions) in the immediate arm and waitlist control arm, respectively (data not shown, P = 0.70). At baseline, the food frequency questionnaire computed mean (s.d.) caloric intake to be 1,290 (635) kcal per day, which is likely a strong under accounting of the diet given the body size of participants. A summary of the dietary changes as measured by food frequency questionnaire is presented in Table 2.
At month 6, participants in the immediate arm self-reported a substantial increase in behaviors related to physical activity and dietary change as assessed by the adherence index, which were largely maintained at month 12 (Table 3). Participants in the waitlist control arm self-reported a substantial increase in behaviors at month 12 that paralleled that of the intervention group. There were no statistically significant differences in change in adherence score at 6 or 12 months by ethnicity (data not shown).
Weight loss—baseline to 6 months. Using intent to treat analysis, participants in the immediate arm lost an average of 3.3% (±3.5%) of total body weight at 6 months, which corresponds to an absolute weight loss of 2.9 (±3.1) kg (range: −10.4 kg to +1.7 kg) (Figure 2 and Table 4). During the same period, the waitlist control group lost an average 1.8% (±2.9%) of body weight, which corresponds to an absolute weight loss of 1.4 (±2.5) kg (range: −5.6 kg to +3.2 kg). The estimated mean difference in weight lost between the two arms at 6 months was −1.8 kg (P = 0.03) and participants in the immediate arm lost weight at a greater rate than those in the waitlist control arm (0.48 kg/month vs. 0.27 kg/month, respectively; P = 0.04, Table 4). There were no statistically significant differences in weight loss by ethnicity (data not shown).
Weight loss—6 months to 12 months. At 6 months, participants in the immediate arm entered into an observation period where they were encouraged to continue losing weight, but their fitness center memberships were no longer paid for by the study. At 6 months, participants in the waitlist control arm began the weight loss program. Participants in the waitlist control arm continued to lose weight during their intervention period, though at a slower rate during the intervention period compared with the immediate arm (Figure 2). On average participants in the immediate arm regained much of the weight that was lost during the 6 month intervention period, although at 12 months remained significantly less heavy than at baseline (P = 0.02, Table 4).
Weight loss by intervention adherence index. We examined the amount of weight loss based on change in the intervention adherence index. Participants with higher adherence lost more percent weight than those with lower adherence (Table 3).
Weight loss by hormonal therapy use among postmenopausal women
Fifty-nine percent of postmenopausal women in the study were on hormonal therapy. Postmenopausal women on hormonal therapy attended a similar number of exercise sessions as those not on hormonal therapy (mean 1.0 ± 0.20 sessions vs. 0.86 ± 0.18 sessions, respectively, P = 0.53). In subgroup analyses, postmenopausal women in the immediate arm who were not on hormonal therapy showed a trend towards losing twice as much weight compared with women who were on hormonal therapy (4.0 ± 1.0% vs. 1.7 ± 0.6%, respectively; P = 0.06).
Changes in other anthropometric measures. At month 3, compared with women in the waitlist control arm, women in the immediate arm showed significant decreases in waist and hip circumferences, but not in waist:hip ratio (Table 4). At month 6, only the significant decrease in waist circumference persisted and was marginally statistically significant (P = 0.07). At month 6, the immediate program arm within-group analyses showed significant decreases in waist circumference, percent body fat, fat body mass, and total body mass.
There were no changes in metabolic biomarkers using intent to treat analyses. When metabolic biomarkers were assessed based on amount of fat lost as assessed by DEXA scan at 6 months, ≥2% fat loss was associated with a statistically significant decrease in insulin, glucose, and HOMA-IR (Table 5). Weight loss ≥5% was associated with a statistically significant increase in IGF binding protein-1 at 6 and 12 months, and a statistically significant decrease in glucose at 12 months (data not shown).
No change was noted in fitness as assessed by VO2max using intention to treat analyses and attendance at exercise sessions (data not shown), though the study was not powered to detect such a difference.
Acceptability of program
At the conclusion of the study, the majority of participants stated that the Curves weight loss program was appropriate for women like themselves. During an exit interview (n = 38), 97% said they would be very likely to recommend the nutrition program and 92% said that they would be very likely to recommend the exercise program. Eighty-nine percent said they were likely or very likely to continue following the nutrition guidelines, but only 18% said they were very likely to continue the exercising at the fitness centers. For 92% of the women, cost was an issue for continuing a fitness center membership.
No serious adverse events were reported during the exercise sessions. One diabetic participant had a hypoglycemic episode upon arrival at a Curves center (after not eating that day and walking up a flight of stairs). During follow-up, one participant reported knee pain with exercise. Of note, no participants self-reported new onset lymphedema or exacerbation of lymphedema and one participant who used a cane upon entry into the study reported that after initiating the exercise program she had increased mobility and no longer needed to use her cane. Two participants in the waitlist control arm were removed from the study before beginning the intervention, one due to breast cancer recurrence and another due to a diagnosis of cardiovascular disease.
This pilot study was designed to test the feasibility and effects of a readily available commercial exercise and dietary change-based weight loss program among overweight and sedentary Hispanic and black breast cancer survivors. We found that it is feasible to recruit and retain these diverse populations of breast cancer survivors to a randomized weight loss trial. The 6-month intervention resulted in moderate weight loss in the short-term, but the weight loss was not maintained after the intervention ended.
This study focused on Hispanic and black breast cancer survivors because these are two populations that may particularly benefit from targeted behavioral modification and weight loss interventions, and to date these populations have been underrepresented in the cancer survivorship literature. At our medical center, 40% of the breast oncology patient population self identifies as Hispanic, African American, and/or Afro-Caribbean. The majority of these women are of low socioeconomic status. At baseline, study participants reported low levels of physical activity, low levels of fruit/vegetable intake, high dietary fat, and had low levels of physical fitness as assessed by VO2max. The study demonstrated that breast cancer survivors from these minority populations are motivated to participate in behavioral modification studies and are able to complete a 12-month study with very little loss to follow-up. However, the particular intervention used in this study may not be the most effective method to achieve sustained behavior change in these particular patient populations.
The Curves Weight Management program was chosen as an intervention strategy because of its novelty as being a community-situated, widely available and easily accessible commercial weight loss program targeted specifically towards women. The Curves program uses the combination of change in diet and an increase in physical activity to achieve weight loss, which has shown to be the most effective method for achieving weight loss (29). Other commercial weight loss programs, such as Weight Watchers, now also advocate combined diet and exercise approaches to successful weight loss. Studies focused on diabetes and cardiovascular disease prevention routinely combine physical activity and dietary change to achieve long-term 7–10% weight loss (31).
We hypothesized that the community-situated approach would facilitate meaningful weight loss in breast cancer survivors, which could be maintained over time. We found that in our study population, the program did achieve an average weight loss of 3.3% after 6 months and that it was not maintained 6 months after the intervention ended. A prior controlled 14-week study using Curves showed an average weight loss of 7%, with additional changes in body composition and metabolic markers (32), but this was in a highly supervised setting with a different patient population. Women in La Vida Activa/An Active Life study reported that they made some of the changes in their dietary behaviors, but were not able to adhere to the targeted frequency of exercise. It is possible that women may need to have a dietary change program that is more convenient for them than a weekly program offered at a medical center, such as a program that is at a more convenient location or that is offered via phone. It is also possible that having a convenient exercise location is not enough for the women to address the barriers to making substantial changes in their physical activity. Participants reported that the fitness centers and nutrition course was appropriate for women like themselves, but they reported that cost was a barrier to continuing to exercise at the fitness centers. At the time the study was proposed, we hypothesized that a $50 membership fee would not be cost-prohibitive. Patients in our clinic were highly enthusiastic about the program in informal conversations; however, the idea was not tested through a focus group or formal interviews. Previous studies have suggested that many Hispanic and black women have cultural barriers that may increase the difficulty of adapting new diet and exercise patterns, including but not limited to perceptions of a healthy and attractive body size and perceptions of the benefits of lifestyle modifications (33,34).
Previously published trials of lifestyle interventions among cancer survivors have demonstrated increased adherence and persistence using motivational interviewing, behavioral counseling, and tailored messages (19,20). Weight loss interventions using the stages of change model have shown that those in the “preparation” stage at recruitment are more likely to make changes than those in the “contemplation” stage (35). Future long-term studies of weight loss should build in motivational tools, behavioral supports, cultural tailoring, and financial feasibility to enhance uptake and to maintain behavioral changes over time.
The La Vida Activa/An Active Life study was designed to test the effects of a specific weight loss program on 12-month weight loss. Long term clinical trials are needed to test the effects of weight loss on breast cancer recurrence and survival and several studies are currently underway (http://projectreporter.nih.gov/reporter.cfm, http://www.clinicaltrials.gov/). The amount, method, or duration of weight loss that would be associated with improved disease-free survival is currently unknown. Hypothesized mechanisms of action of weight loss include metabolic/insulin-like growth factor (IGF) and hormonal pathways (4,36,37). Waist circumference, which correlates with visceral adiposity and insulin resistance, is one of the metabolic syndrome criteria and is a risk factor for breast cancer (38). Weight loss interventions have changed metabolic biomarkers related to breast cancer risk, such as IGF-1 and insulin (19,37). As observed in other studies, we observed that weight loss ≥5% and fat mass loss ≥2% were both associated with changes in metabolic biomarkers related to breast cancer risk.
In exploratory analyses of women in the immediate arm, postmenopausal women not on hormonal therapy lost almost twice as much weight compared with women on hormonal therapy. It is possible that hormonal therapy may be associated with weight retention (39) or that aromatase inhibitor-induced arthralgias interfered with their ability to exercise (40). Further research is needed to understand clinical factors that may facilitate or hinder weight loss.
The La Vida Activa/An Active Life study is one of a few studies focused on weight loss among Hispanic and black breast cancer survivors, which are two populations at high risk of breast cancer recurrence and who may benefit from targeted behavioral interventions. Study limitations include the short duration of intervention, small sample size, and low exercise attendance. It is likely that our measure of diet, a food frequency questionnaire designed to include food items specific to Hispanic and black populations, did not accurately capture dietary intake. Our measure of adherence was created for this specific intervention and is not a validated measure. It is important to note that participants in the waitlist control arm lost substantial weight during their waitlist control period, suggesting that at the time of enrollment these women were motivated to lose weight. Future controlled weight loss studies in this population should design an appropriate control arm that either emphasizes the need for the maintenance of prerandomization dietary intake and energy expenditure, or engages the control group in a control intervention that accounts for time spent in group activities and behavior change. Strengths of the study include using both objective measures and patient reported outcomes, and testing in both pre- and postmenopausal women.
In this pilot study, we have demonstrated that it is possible to recruit and retain Hispanic and black breast cancer survivors to a weight loss intervention. We demonstrated that the intervention is effective among adherers in our local population of overweight/obese and sedentary minority breast cancer survivors, but that behavioral support and a financially sustainable program may be needed to increase intervention uptake and maintenance of behaviors. Further research on barriers to participation, optimal dose, and duration are necessary to understand the effects of combined exercise and dietary change interventions on breast cancer survival.
The authors wish to thank the women who participated in this study, Marcia De Leon and Nancy Mendez who taught the nutrition sessions, and the participating Curves franchise owners who made in kind donations by waiving membership initiation fees. We thank Cristina Valdovinos for her assistance with manuscript preparation. This research was supported by Gateway for Cancer Research (H.G.), Women At Risk (H.G), the Susan G. Komen Foundation (D.L.H), and Grant Number UL1 RR024156 from the National Center for Research Resources, a component of the National Institutes of Health (NIH) and NIH Roadmap for Medical Research. The contents of this publication are solely the responsibility of the authors and do not necessarily represent the official views of the funding agencies.
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