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Keywords:

  • physical activity;
  • sedentary time;
  • health-related quality of life;
  • accelerometer

Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. FUNDING SUPPORT
  8. CONFLICT OF INTEREST DISCLOSURES
  9. REFERENCES

BACKGROUND

The primary purpose of this study was to determine associations of accelerometer-assessed moderate- to vigorous-intensity physical activity (MVPA) and sedentary time with health-related quality of life (HRQoL) and physical function and well-being in colon cancer survivors.

METHODS

Colon cancer survivors (N = 178) from Alberta, Canada (n = 92) and Western Australia (n = 86) completed a mailed survey that assessed HRQoL (Functional Assessment of Cancer Therapy–Colorectal), physical function and well-being (Trial Outcome Index–Colorectal), and relevant covariates. MVPA and sedentary time were assessed using the Actigraph GT3X+ accelerometer (60-second epochs) via a 7-day monitoring protocol. Average daily MVPA and sedentary time was corrected for wear time and then examined as quartiles.

RESULTS

Adjusting for relevant demographic, behavioral, and clinical covariates, a significant difference in HRQoL scores emerged between quartile 1 (Q1) and Q4 (Mdiff = 11.5, P = .038). For physical function and well-being, a significant difference emerged between Q1 and Q4 (Mdiff = 9.1, P = .009). For fatigue, a significant difference emerged between Q1 and Q4 (Mdiff = 7.1, P = .05). Significant differences were also observed for between Q1 and Q3 (Mdiff = 2.4, P = .041), and Q1 and Q4 (Mdiff = 3.5, P = .002) for colorectal cancer–specific symptoms. There were no statistically significant associations of sedentary time with HRQoL, physical function and well-being, fatigue, or colorectal cancer–specific symptoms.

CONCLUSIONS

Objectively measured MVPA, but not sedentary time, was associated with better HRQoL, physical function and well-being, and colorectal cancer–specific symptoms in colon cancer survivors. For MVPA, differences met or exceeded contemporary cutpoints for determining clinically important differences. Cancer 2014;120:2919–2926. © 2014 American Cancer Society.


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. FUNDING SUPPORT
  8. CONFLICT OF INTEREST DISCLOSURES
  9. REFERENCES

A consistent and growing body of literature indicates regular and sustained moderate-vigorous physical activity (MVPA) is associated with health-related quality of life (HRQoL) and reduced fatigue symptoms among colorectal cancer survivors.[1-3] A major limitation across all of the studies to date is the use of self-report measures to assess MVPA. Self-report estimates are prone to measurement error that often leads to incorrect inferences about MVPA behaviors (and physical activity in general) and may bias study results.[4]

Cancer survivors spend upward of 70% of their day in sedentary behavior.[5] Not to be confused with a lack of physical activity (ie, not meeting physical activity guidelines), sedentary behaviors are waking activities performed in a seated or reclining posture that require very low energy expenditure (≤1.5 metabolic equivalents).[5, 6] A rapidly expanding body of research indicates that sedentary behavior has potentially deleterious health consequences; we recently highlighted the importance of furthering our understanding of sedentary behavior across the cancer context.[7]

Few studies of cancer survivors have examined sedentary behavior and associations with HRQoL and fatigue. Four studies have shown significant associations of sedentary behavior with HRQoL and fatigue, among cancer survivors.[2, 8-10] However, these studies used self-report measures of sedentary behavior, and are thus subject to similar issues of reporting bias that occur with physical activity studies using self report measurement tools.

Objective measurement of physical activity and sedentary behavior (via accelerometer) enables accurate, precise, and reliable measurement of the wide spectrum of movement and sedentary time throughout the day. Importantly, objective measurement also records how sedentary time and physical activities are accumulated (ie, prolonged, unbroken bouts, or through numerous short bouts interspersed with other activities).

The primary objective of this study was to determine the associations of objectively assessed MVPA with HRQoL and physical function and well-being among a sample of colon cancer survivors. The secondary objectives were to determine 1) associations of objectively assessed sedentary time with HRQoL and physical function and well being, 2) associations of objectively assessed sedentary time with fatigue and colorectal-specific concerns, and 3) whether prolonged bouts of MVPA (ie, total MVPA time accumulated in at least 10-minute bouts) and sedentary time (ie, total sedentary time accumulated in at least 30-minute bouts) are associated with HRQoL and physical function and well-being among colon cancer survivors. We hypothesized objectively assessed MVPA and sedentary time would be significantly associated (both statistical and clinical significance) with HRQoL and physical function and well-being.

MATERIALS AND METHODS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. FUNDING SUPPORT
  8. CONFLICT OF INTEREST DISCLOSURES
  9. REFERENCES

Participants

We recruited colon cancer survivors from Alberta, Canada, as well as Western Australia. Eligible survivors were identified and recruited through the Alberta Cancer Registry and the Western Australian (WA) Cancer Registry (Department of Health WA). The study was approved by local ethics boards at Alberta Health Services, Athabasca University, and the Department of Health WA and The University of Western Australia.

The Alberta Cancer Registry and the WA Cancer Registry identified colon cancer survivors with histologically confirmed stage I to III diagnosis of a first, primary colon cancer (although participants with a stage IV diagnosis at the time of study participation were not excluded). Eligibility criteria included speaking English and being between the ages of 18 and 80 years. Eligible survivors had to 1) not be currently undergoing any adjuvant therapy, 2) be able to understand and provide written informed consent, and 3) be willing and able to wear an accelerometer for 7 days. The recruitment protocol between the 2 study sites was identical.

Registry Procedures

Survivors were mailed a study invitation package containing 1) a letter from the registry describing the role of the registry in this study and the general purpose of the registry, and 2) an invitation letter from the research team explaining the nature of the research study and what would be required of the participant. Survivors received a follow-up reminder postcard 2 weeks after the initial mail-out. Participants who were eligible and willing to take part in the study were then sent a package containing a survey, an Actigraph GT3X+ accelerometer (Actigraph LLC, Pensacola, Fla), a detailed instructional pamphlet describing how to use the accelerometer, and a padded, postage-paid, priority post return envelope. At the end of the 7-day monitoring period, participants returned their signed consent form, completed survey, and accelerometer in the priority post envelope.

Measures

Demographic and medical information obtained from the Alberta Cancer Registry included date of diagnosis, age at diagnosis, stage, and types of treatments received (eg, surgery, chemotherapy, radiation therapy). In WA, date of diagnosis and stage were obtained from the WA Cancer Registry, whereas treatment information was gathered from the participant via self-report. Demographic and medical information including sex, age, employment, marital status, income, education, ethnicity, height and weight, was also collected via self-report. To collect comorbidity information, participants were asked to indicate the presence or absence of 6 common comorbidities (eg, heart attack, angina, high blood pressure, high blood cholesterol, stroke, diabetes). One open-ended question labeled “other” allowed participants to specify other comorbidities not listed (eg, arthritis, osteoporosis).

Physical activity and sedentary time

Physical activity and sedentary time were derived from an Actigraph GT3X+ accelerometer. This instrument records acceleration using a triaxial accelerometer. Participants were provided with the accelerometer and instructed to wear it on their right hip attached by an elastic belt during all waking hours for 7 consecutive days. Participants were asked to record, in a daily log, the time they put on and took off the monitor each day. Participants returned their accelerometer, survey, and logbook to the study coordinators by priority post. A pragmatic cutoff of <100 counts per minute was used to categorize sedentary time.[11] Commonly accepted activity count cutoffs were used to differentiate MVPA (counts per minute ≥1952) from light intensity activity (100-1951 counts per minute).[12] Data were recorded in 60-second epochs. Nonwear time was defined as intervals of at least 60 consecutive minutes of zero counts, with allowance for up to 2 minutes of observations of < 50 counts per minute within the nonwear interval.[11] To be considered valid, days of data collection required at least 600 minutes (10 hours) of wear time and no excessive counts (> 20,000 counts per minute).

Health-related quality of life

HRQoL was assessed by the Functional Assessment of Cancer Therapy–Colorectal (FACT-C).[13, 14] The FACT-C is a 34-item questionnaire assessing physical well-being (7 items); social/family well-being (7 items); emotional well-being (6 items); functional well-being (7 items); and colorectal cancer-specific symptoms (CCS) (7 items). Survivors were asked to rate how they have felt over the past 7 days, on a scale of 0 (“not at all”) to 4 (“very much”). Each subscale was scored and then summed to provide an overall HRQoL score. Differences of at least 5 points on the FACT-C and 2 to 3 points on the CCS are considered a clinically important difference (CID),[14] which is the smallest difference in score in the domain of interest that patients perceive as important, leading the clinician to consider a change in the patient's management.[15]

Physical function and well-being

Physical function and well-being was assessed using the Trial Outcome Index-Colorectal (TOI-C). The TOI-C is the sum of the physical and functional well-being scales, with the addition of the colorectal cancer–specific symptoms subscale (Nitems = 21). The TOI-C is a summary measure of physical function and well-being.[14] A difference of at least 4 points on the TOI-C is considered a CID.[14]

Fatigue

Fatigue was assessed with the 13-item FACT Fatigue Scale (FS) from the FACT measurement system.[16] A difference of 3 points on the FS is considered a CID.[17] The FACT-C and FS scales have suitable evidence of internal consistency, test–retest reliability, and convergent and discriminant validity.[16, 18]

Statistical Analyses

Descriptive statistics were used to examine the demographic, health, and medical characteristics of the sample. Univariate analysis of variance (ANOVA) procedures were used to test for differences in HRQoL (ie, FACT-C and TOI-C) across quartiles of MVPA, MVPA time accumulated in at least 10-minute bouts, sedentary time, and sedentary time accumulated in at least 30-minute bouts. Analyses also compared participants meeting MVPA guidelines (ie, >150 minutes of MVPA per week) to those not meeting guidelines. Pairwise comparison procedures were conducted on all significant ANOVA statistics. Covariates were included if they had 1) any evidence of association (P < .20) with the dependent variable, and 2) demonstrated clinical relevance based on previous research. All models covaried on sex, age, smoking, study site (Alberta/Australia), total sedentary minutes (for MVPA models), total MVPA minutes (for sedentary time models), comorbidity (at least 1 comorbidity versus no comorbidity), months since diagnosis, and chemotherapy (received chemotherapy versus no chemotherapy). Sidak corrections were applied to all comparisons [ie, 1 − (1 − α)1/C where C is the number of comparisons]. An alpha (α) of 0.05 was used as a threshold for determining statistical significance.

RESULTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. FUNDING SUPPORT
  8. CONFLICT OF INTEREST DISCLOSURES
  9. REFERENCES

Participant Characteristics

A total of 927 eligible colon cancer survivors received study invitation packages in Alberta (n = 641) and Western Australia (n = 286). In Alberta, 97 participants completed and returned study information for a 15.1% response rate. In Western Australia, 100 participants completed and returned study information for a 34.9% response rate. Overall, 197 survivors responded to the registry mail-outs representing a response rate across the 2 study sites of 21.3%. Overall, 181 participants provided complete accelerometer and HRQoL data. However, 3 of these participants had stage IV disease and were excluded from all analyses for a final sample size of 178. Participants did not significantly differ from the 16 participants who had missing accelerometer or HRQoL data on any demographic, clinical, or behavioral characteristics. We compared WA and AB participants on demographic, behavioral, and clinical characteristics. AB participants were, on average, ∼3 years younger than WA participants (P = .029). Significantly more WA participants reported at least 1 comorbidity (73%) compared to AB participants (52%) (P = .004). WA participants were, on average, 17 months postdiagnosis compared to AB participants who were, on average, 20.6 months since diagnosis (P < .001). There were no other medical (eg, treatment, cancer stage) or behavioral (eg, MVPA, sedentary time) differences between the groups.

Information pertaining to the demographic, medical, and behavioral characteristics of the sample is shown in Table 1. In summary, the mean age of our sample was 64.3 years (SD = 10.2) and the mean number of months since diagnosis was 18.9 (SD = 4.3). Approximately 56% of the sample was male. Medical data indicated 39% of participants had stage III disease and 45% received chemotherapy. When considering total MVPA minutes, approximately 53.4% of participants were achieving at least 150 minutes of MVPA per week. However, when considering only MVPA minutes accumulated in at least 10-minute bouts (as per public health physical activity guidelines), only 15.7% of participants were achieving guidelines (Table 2).

Table 1. Demographic, Health, and Medical Characteristics
CharacteristicNo. of Respondenta% (Mean ± SD)b
Demographic  
  1. a

    Numbers may not equal 178 due to missing data.

  2. b

    Data are presented as the mean (standard deviation) for continuous variables and frequency (percentage) for categorical variables.

Sex  
Male9955.6
Female7944.4
Age17864.3 ± 10.3
Marital Status178 
Married13073.0
Widowed169.0
Separated/divorced147.8
Common-in-law105.6
Never married84.5
Education178 
Some high school3016.9
Completed high school2514.1
Diploma or certificate3318.6
Trade or apprenticeship3016.9
Some university/college2212.4
Completed university/college1810.2
Some graduate school63.4
Completed graduate school137.3
Annual Family Income171 
<$20,000137.6
$20,000-$39,9994727.5
$40,000-$59,9993118.1
$60,000-$79,9992715.8
$80,000-$99,999158.8
$≥100,0003822.2
Employment Status176 
Retired9151.7
Disability63.4
Employed full/part-time6838.7
Temporarily unemployed31.7
Homemaker84.5
Medical/health  
Body mass index (kg/m2)17027.1 ± 5.3
Normal weight5632.9
Overweight7644.7
Obese3822.4
Months since diagnosis17818.9 ± 4.4
Stage178 
15631.4
25329.8
36938.8
Chemotherapy178 
Yes8044.9
Smoking178 
Never smoke4123.0
Used to smoke7843.8
Currently smoke5933.1
Comorbidity history  
At least one comorbidity11162.4
Angina84.5
Heart attack169.0
Stroke52.8
Diabetes2413.5
High blood pressure7341.2
High blood cholesterol5732.0
Other168.8
Table 2. Descriptive Statistics for Physical Activity, Sedentary Time, and Health-Related Quality of Life Variables (N = 178).
VariableMeanSD
  1. Data are presented as the mean ± standard deviation for continuous variables and frequency % for categorical variables.

  2. a

    Moderate and vigorous minutes combined.

  3. b

    MVPA time accumulated in at least 10-minute bouts.

  4. c

    Engage in moderate-intensity physical activity for a minimum of 150 minutes of MVPA a week. Activity performed in at least 10-minute bouts.

  5. d

    Sedentary time accumulated in at least 30-minute bouts.

Physical activity/sedentary time  
Accelerometer wear time (minutes/day)867.073.9
Valid days6.61.2
Light minutes/day310.682.8
Moderate minutes/day27.721.6
Vigorous minutes/day0.93.0
Moderate-vigorous (MVPA) minutes/daya28.522.3
MVPA/day in 10-minute boutsb8.813.5
% achieving MVPA guidelinesc15.7% 
Sedentary time/day527.989.1
Sedentary time in 30-minute bouts/dayd152.9102.0
Health-related quality of life  
FACT-Colorectal (0-136)110.817.5
TOI-Colorectal (0-84)70.012.0
Fatigue (0-52)41.310.8
Colorectal symptoms (0-28)23.04.0

MVPA

On average, participants spent 28.5 (SD = 22.3) minutes per day engaged in MVPA. Cutpoints for MVPA minutes were < 12.0 (Q1), 12.0 to < 23.6 (Q2), 23.6 to < 39.9 (Q3), and ≥ 39.9 (Q4). After adjusting for relevant demographic, behavioral, and clinical covariates, significant trends emerged for FACT-C (Ptrend = .001; Fig. 1), TOI-C (Ptrend = .001; Fig. 2), FS (Ptrend = .015; Fig. 3), and CCS (Ptrend ≤ .001; Fig. 4). A significant difference in FACT-C scores emerged between Q1 and Q4 (Mdiff = 11.5, P = .038). For the TOI-C, a significant difference emerged between Q1 and Q4 (Mdiff = 9.1, P = .009). For Fatigue, a significant difference emerged between Q1 and Q4 (Mdiff = 7.1, P = .05). For CCS, significant differences emerged between Q1 and Q3 (Mdiff = 2.4, P = .041) and Q1 and Q4 (Mdiff = 3.5, P = .002). All of these differences exceeded the thresholds for determining a CID.

image

Figure 1. Health-related quality of life difference scores across moderate- to vigorous-intensity physical activity (MVPA) quartiles. *P ≤ .05; **P < .01. Dagger (†) denotes meeting clinically important difference threshold (5-8 points for Functional Assessment of Cancer Therapy–Colorectal [FACT-C]). Model adjusted for sex, age, months since diagnosis, chemotherapy, comorbidity, stage, smoking, study site (Alberta/Australia), and sedentary time. CI indicates confidence interval.

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image

Figure 2. Trial Outcome Index–Colorectal (TOI-C) difference scores across moderate- to vigorous-intensity physical activity (MVPA) quartiles. *P ≤ .05; **P < .01. Dagger (†) denotes meeting clinically important difference threshold (4-6 points for TOI-C). Model adjusted for sex, age, months since diagnosis, chemotherapy, comorbidity, stage, smoking, study site (Alberta/Australia), and sedentary time. CI indicates confidence interval.

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image

Figure 3. Fatigue difference scores across moderate- to vigorous-intensity physical activity (MVPA) quartiles. *P ≤ .05; **P < .01. Dagger (†) denotes meeting clinically important difference threshold (3 points for fatigue). Model adjusted for sex, age, months since diagnosis, chemotherapy, comorbidity, stage, smoking, study site (Alberta/Australia), and sedentary time. CI indicates confidence interval.

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image

Figure 4. Colorectal cancer–specific (CCS) symptom difference scores across MVPA quartiles. *P ≤ .05; **P < .01. Dagger (†) denotes meeting clinically important difference threshold (2-3 points for CCS). Model adjusted for sex, age, months since diagnosis, chemotherapy, comorbidity, stage, smoking, study site (Alberta/Australia), and sedentary time. CI indicates confidence interval.

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Compared to participants not meeting MVPA guidelines (<150 minutes of MVPA a week), participants meeting MVPA guidelines (≥150 minutes of MVPA a week) reported significantly better scores on HRQoL (Mdiff = 6.9, P = .018), TOI-C (Mdiff = 4.9, P = .014), Fatigue (Mdiff = 4.1, P = .027) and CCS (Mdiff = 2.1, P = .002). These differences met or exceeded thresholds for determining a CID.

Sedentary Time

On average, participants spent 527.9 (SD = 89.1) minutes per day (ie, 8.8 hours) in sedentary time. Cutpoints for sedentary minutes were <473.2 (Q1), 473.2 to <526.9 (Q2), 526.9 to <592.2 (Q3), and ≥592.2 (Q4). There were no significant trends for sedentary time across HRQoL, TOI-C, FS, and CCS (all P values < .05). CIDs emerged between Q1 and Q2 for HRQoL (Mdiff = 4.6) and Q1 and Q2 for TOI-C (Mdiff = 3.9). However, these differences were not statistically significant.

MVPA in 10-Minute Bouts

Participants accumulated an average of 8.8 (SD = 13.5) minutes per day of MVPA accumulated in at least 10-minute bouts. Cutpoints for MVPA minutes accumulated in minimum 10-minute bouts were <.28 (Q1), .28 to <4.4 (Q2), 4.4 to <13.4 (Q3), and ≥13.4 (Q4). Significant trends were observed for HRQoL (Ptrend = .035), TOI-C (Ptrend = .028), and CCS (Ptrend = .003). A significant difference in CCS emerged between Q1 and Q4 (Mdiff = 2.4, P = .04). CIDs emerged between Q1 and Q4 (Mdiff = 7.5) for HRQoL; Q1 and Q4 for TOI-C (Mdiff = 5.1); and Q1 and Q4 for FS (Mdiff = 3.5). However, these differences were not statistically significant. When considering MVPA accrued in at least 10-minute bouts, participants meeting MVPA guidelines did not report significantly better scores on any of the HRQoL and physical function and well-being variables (all P values > .05).

Sedentary Time in 30-Minute Bouts

Participants accumulated an average of 152.9 minutes (SD = 102.0) of sedentary time in at least 30-minute bouts. Cutpoints for total sedentary time accumulated in at least 30 minute bouts were <80.3 (Q1), 80.3 to <132.4 (Q2), 132.4 to <206.7 (Q3), and ≥206.7 (Q4). No significant trends emerged across HRQoL, TOI-C, FS, or CCS (all P values > .05).

DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. FUNDING SUPPORT
  8. CONFLICT OF INTEREST DISCLOSURES
  9. REFERENCES

The primary objective of this study was to determine the associations of objectively assessed MVPA with HRQoL and physical function and well-being (ie, TOI-C) among a sample of colon cancer survivors. In support of our hypotheses, we observed significant associations of objectively assessed MVPA with HRQoL (FACT-C), physical function and well being (TOI-C), and colorectal cancer–specific symptoms (CCS). Differences in HRQoL, physical function and well-being, colorectal cancer symptoms, and fatigue also exceeded thresholds for determining a CID; the smallest difference which individuals and health care providers perceive as beneficial and which would mandate a change in the individual's management.[19] Associations with sedentary time were not significant, although differences emerged that met thresholds for determining a CID.[17, 20]

Associations observed for MVPA corroborate previously published research examining self-reported MVPA and HRQoL outcomes (including the examination of CIDs) among colorectal cancer survivors. Although our primary analyses analyzed MVPA in quartiles, our secondary analyses examining participants meeting MVPA guidelines (ie, ≥150 minutes of MVPA per week) corroborates previously published research. Among a sample of 413 colorectal cancer survivors, Peddle and colleagues[3] reported those meeting public health physical activity guidelines reported significantly higher HRQoL on the FACT-C (Mdiff = 6.0) compared to survivors not achieving guidelines. Their reported mean difference is similar to our observed mean difference of 6.8 points. Our quartile analyses support a dose-response relationship and indicate greater differences in HRQoL are apparent when comparing participants doing the most MVPA to participants doing the least amounts of MVPA (Table 3). Other cross-sectional studies using self-report measures of MVPA have found significant associations with HRQoL.[1, 21, 22] In a large prospective study, Lynch and colleagues examined 1966 colorectal cancer survivors (at 6, 12, and 24 months after diagnosis) and found, at any given time point, participants achieving at least 150 minutes of MVPA per week had an 18% higher HRQoL score than those who reported no activity.[2] We found participants in Q4 had a 9% higher FACT-C score compared to those in Q1. Participants meeting MVPA guidelines reported a 5.1% higher FACT-C score compared to those not meeting MVPA guidelines. To date, our study is one of the first to examine objectively assessed MVPA and associations with HRQoL and other related outcomes (ie, physical function and well-being, colorectal cancer symptoms, and fatigue) among colon cancer survivors.

Table 3. Adjusted Mean and Standard Error Across Quartiles of Accelerometer-Derived MVPA and Sedentary Time Variables
ModelQuartile 1 (referent) (n = 44)Quartile 2 (n = 45)Quartile 3 (n = 45)Quartile 4 (n = 44)P for Trend
  1. a

    P < .05;

  2. b

    P < .01 for pairwise comparisons.

  3. Note: Sidak corrections were applied to all comparisons [ie, 1–(1-α)1/C where C is the number of comparisons].

  4. MVPA quartiles and sedentary quartiles adjusted for accelerometer wear time.

  5. Models adjusted for sex, age, months since diagnosis, chemotherapy, comorbidity, stage, smoking, study site (Alberta/Australia), and sedentary time (for MVPA model) and MVPA (for sedentary time model).

MVPA     
FACT-C104.8 (2.8)109.5 (2.7)112.7 (2.7)116.3 (2.8)a.005
TOI-C65.2 (1.9)69.7 (1.8)70.8 (1.8)74.4 (1.9)b.002
Fatigue37.6 (1.8)41.4 (1.7)41.2 (1.7)44.7 (1.8)a.014
Colorectal symptoms21.1 (0.6)22.8 (0.6)23.5 (0.6)a24.6 (0.6)b<.001
MVPA: ≥10-minute bouts     
FACT-C106.7 (2.7)111.1 (2.7)111.3 (2.7)114.1 (2.7).067
TOI-C67.8 (1.9)69.5 (1.8)70.0 (1.8)72.9 (1.8).061
Fatigue40.4 (1.8)40.7 (1.7)40.2 (1.7)43.9 (1.7).189
Colorectal symptoms21.8 (0.6)22.9 (0.6)23.2 (0.6)24.2 (0.6)a.007
Sedentary time     
FACT-C108.4 (3.0)113.0 (2.6)110.0 (2.6)111.8 (2.8).711
TOI-C68.8 (2.1)72.7 (1.8)69.0 (1.8)69.6 (1.9).714
Fatigue41.0 (1.9)42.6 (1.7)40.5 (1.7)41.1 (1.8).750
Colorectal symptoms22.3 (0.7)24.0 (0.6)22.8 (0.6)23.0 (0.6).912
Sedentary time: ≥30-minute bouts     
FACT-C110.0 (2.7)110.5 (2.7)109.0 (2.6)113.8 (2.7).261
TOI-C69.5 (1.8)69.9 (1.8)69.6 (1.8)71.1 (1.9).600
Fatigue41.3 (1.7)40.2 (1.7)42.4 (1.7)41.3 (1.7).823
Colorectal symptoms22.3 (0.6)22.9 (0.6)23.0 (0.6)23.8 (0.6).112

When considering MVPA accumulated in bouts of at least 10 minutes as per the US Department of Health and Human Services physical activity recommendation (ie, aerobic activity should be performed in bouts of at least 10 minutes),[23] the magnitude of the associations of MVPA with scores on the FACT-C, TOI-C, FS, and CCS were reduced. Several differences still met the threshold for determining CIDs for FACT-C, TOI-C, FS, and CCS. These findings suggest that it may be the overall dose of MVPA that is more strongly associated with these HRQoL outcomes, regardless of how MVPA minutes are accrued throughout the day (ie, in prolonged bouts of at least 10 minutes). It is unknown why associations were smaller given that many self-report MVPA assessments used in the cancer context ask participants to specifically recall, and report bouts of MVPA lasting at least 10 minutes in duration.

Contrary to our hypothesis, sedentary time was not significantly associated with HRQoL and related outcomes among our sample of colon cancer survivors. Only recently have researchers examined sedentary time and associations with health outcomes among cancer survivors. Although sedentary time among cancer survivors is generally high,[9] associations with HRQoL and other psychosocial health outcomes are still relatively unknown. The only study of colorectal cancer survivors found that survivors who watched television more than 5 hours per day had a 16% lower total HRQoL score than survivors watching less than 2 hours per day.[24] Furthermore, survivors who increased their TV viewing from one category to the next have significantly lower QOL than those who maintained or decreased their TV viewing. Deleterious associations of television viewing time were found across all HRQoL subscales. In 2 other studies, breast cancer[8] and kidney cancer[10] survivors exhibited no associations of self-reported sedentary time with HRQoL or fatigue. Although one study found a significant interaction with age suggesting sitting time among younger kidney cancer survivors may be linked to HRQoL.[10] Furthermore, one study with 483 rural breast cancer survivors suggested that fatigue was significantly associated with daily minutes of sitting.[25] With our findings, it is possible that only context-specific sedentary behaviors (eg, screen time) may be associated with HRQoL rather than overall sedentary time. The failure to reject the null hypothesis may have been attributed to the relatively healthy sample that reported favorable HRQoL and fatigue profiles.

Given the limited research examining objectively assessed MVPA and sedentary time among colon cancer survivors, one must take caution in interpreting our results. Because the accelerometers used in this study do not provide information about specific behaviors or the setting within which they occur, it may be possible that true sedentary behavior (ie, sitting) may be associated with adverse HRQoL, physical function and well-being, fatigue, and colorectal cancer symptom outcomes. In our study, the possible inclusion of stationary standing in the sedentary time data may have minimized associations that may have been observed with sitting. Future research could use a more precise and more sensitive device to measure sitting time, such as the ActivPAL (Glasgow, UK),[26] to specifically examine sitting behaviors, and in particular prolonged unbroken bouts of sitting, and consequences on HRQoL, physical function and well-being, fatigue, and colorectal cancer symptoms. The difference in response rates between the 2 study sites was sizeable and may limit the generalizability of our findings. We assessed participant comorbidities with a self-report assessment of primarily cardiovascular comorbidities (eg, high blood pressure, angina, stroke) and diabetes with one open-ended question for the participant to indicate additional comorbidities. Such an approach only elicits the presence or absence of comorbidity, and not the degree to which the comorbidity influences physical activity and/or sedentary time. The limited assessment of comorbidities may have reduced the notification of other possible comorbidities. Finally, participants with more advanced disease (or treatment-related side effects and complications) may have been less likely to respond to our study, where more healthy participants may have been more likely to respond to our study.

In conclusion, objectively assessed MVPA is significantly associated with HRQoL, physical function and well-being, and colorectal cancer symptoms in colon cancer survivors. Significant associations did not emerge for sedentary time. The cross-sectional design of this study precludes any causal inference. However, the associations shown here highlight new and interesting connections of objectively assessed MVPA and sedentary time with HRQoL and related outcomes among colon cancer survivors that should be investigated further in prospective studies or intervention trials.

FUNDING SUPPORT

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. FUNDING SUPPORT
  8. CONFLICT OF INTEREST DISCLOSURES
  9. REFERENCES

Drs. Vallance and Courneya are supported by the Canada Research Chairs program. Dr. Vallance is also supported by a Population Health Investigator Award from Alberta Innovates–Health Solutions. Dr. Lynch is supported by a NHMRC Public Health Training Fellowship (#586727) and the Victorian Government's Operational Infrastructure Support Program.

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. FUNDING SUPPORT
  8. CONFLICT OF INTEREST DISCLOSURES
  9. REFERENCES
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