Incident malignancies among older long-term breast cancer survivors and an age-matched and site-matched nonbreast cancer comparison group over 10 years of follow-up

Authors

  • Kerri M. Clough-Gorr DSc, MPH,

    Corresponding author
    1. Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland
    2. Section of Geriatrics, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
    3. National Institute for Cancer Epidemiology and Registration, Zurich, Switzerland
    • Boston Medical Center, 88 East Newton Street, Robinson 2, Boston, MA 02118

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    • Fax: (617) 638-8387

  • Soe Soe Thwin PhD, MS,

    1. Section of Geriatrics, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
    2. Massachusetts Veterans Epidemiology Research and Information Center, Veterans Affairs Healthcare System, Boston, Massachusetts
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  • Jaclyn L. F. Bosco PhD, MPH,

    1. Section of Geriatrics, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
    2. Dana-Farber Cancer Institute, Boston, Massachusetts
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  • Rebecca A. Silliman MD, PhD,

    1. Section of Geriatrics, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
    2. Department of Epidemiology, Boston University School of Public Heath, Boston, Massachusetts
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  • Diana S. M. Buist PhD,

    1. Group Health Research Institute, Seattle, Washington
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  • Pamala A. Pawloski PharmD,

    1. HealthPartners Research Foundation, Bloomington, Minnesota
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  • Virginia P. Quinn PhD,

    1. Research and Evaluation, Kaiser Permanente Southern California, Pasadena, California
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  • Marianne N. Prout MD, MPH

    1. Department of Epidemiology, Boston University School of Public Heath, Boston, Massachusetts
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  • Presented in part at the 18th Annual Health Maintenance Organization Research Network Conference; April 29 to May 2, 2012; in Seattle, WA.

  • The sponsors had no role in the study design, methods, subject recruitment, data collection, or analysis or in article preparation.

Abstract

BACKGROUND:

Of the approximately 2.4 million American women with a history of breast cancer, 43% are aged ≥65 years and are at risk for developing subsequent malignancies.

METHODS:

Women from 6 geographically diverse sites included 5-year breast cancer survivors (N = 1361) who were diagnosed between 1990 and 1994 at age ≥65 years with stage I or II disease and a comparison group of women without breast cancer (N = 1361). Women in the comparison group were age-matched and site-matched to breast cancer survivors on the date of breast cancer diagnosis. Follow-up began 5 years after the index date (survivor diagnosis date or comparison enrollment date) until death, disenrollment, or through 15 years after the index date. Data were collected from medical records and electronic sources (cancer registry, administrative, clinical, National Death Index). Analyses included descriptive statistics, crude incidence rates, and Cox proportional hazards regression models for estimating the risk of incident malignancy and were adjusted for death as a competing risk.

RESULTS:

Survivors and women in the comparison group were similar: >82% were white, 55% had a Charlson Comorbidity Index of 0, and ≥73% had a body mass index ≤30 kg/m2. Of all 306 women (N = 160 in the survivor group, N = 146 in the comparison group) who developed a first incident malignancy during follow-up, the mean time to malignancy was similar (4.37 ± 2.81 years vs 4.03 ± 2.76 years, respectively; P = .28), whereas unadjusted incidence rates were slightly higher in survivors (1882 vs 1620 per 100,000 person years). The adjusted hazard of developing a first incident malignancy was slightly elevated in survivors in relation to women in the comparison group, but it was not statistically significant (hazard ratio, 1.17; 95% confidence interval, 0.94-1.47).

CONCLUSIONS:

Older women who survived 5 years after an early stage breast cancer diagnosis were not at an elevated risk for developing subsequent incident malignancies up to 15 years after their breast cancer diagnosis. Cancer 2013. © 2012 American Cancer Society.

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