Body mass index and survival in women with breast cancer—systematic literature review and meta-analysis of 82 follow-up studies

• Published in: Annals of oncology Vol. 25; no. 10; pp. 1901 - 1914
• Main Authors: Chan, D.S.M., Vieira, A.R., Aune, D., Bandera, E.V., Greenwood, D.C., McTiernan, A., Navarro Rosenblatt, D., Thune, I., Vieira, R., Norat, T.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-10-2014; Oxford University Press; Elsevier
• Subjects: Antineoplastic agents; Biological and medical sciences; Body Mass Index; Breast Neoplasms - epidemiology; Breast Neoplasms - pathology; Female; Follow-Up Studies; Gynecology. Andrology. Obstetrics; Humans; Mammary gland diseases; Medical sciences; MEDLINE; meta-analysis; Multiple tumors. Solid tumors. Tumors in childhood (general aspects); Obesity - complications; Obesity - epidemiology; Pharmacology. Drug treatments; Prognosis; Randomized Controlled Trials as Topic; Reviews; Risk Factors; survival after breast cancer; Survivors; systematic literature review; Tumors; meta-analysis; survival after breast cancer; body mass index; systematic literature review; Human; Breast disease; Systematic review; Breast cancer; Malignant tumor; Review; Survival; Metaanalysis; Mammary gland diseases; Body mass index; Follow up study; Adult; Female; Woman; Bibliographic review; Cancer
• ISSN: 0923-7534; 1569-8041; 1569-8041
• DOI: 10.1093/annonc/mdu042

Positive association between obesity and survival after breast cancer was demonstrated in previous meta-analyses of published data, but only the results for the comparison of obese versus non-obese was summarised.
We systematically searched in MEDLINE and EMBASE for follow-up studies of breast cancer survivors with body mass index (BMI) before and after diagnosis, and total and cause-specific mortality until June 2013, as part of the World Cancer Research Fund Continuous Update Project. Random-effects meta-analyses were conducted to explore the magnitude and the shape of the associations.
Eighty-two studies, including 213 075 breast cancer survivors with 41 477 deaths (23 182 from breast cancer) were identified. For BMI before diagnosis, compared with normal weight women, the summary relative risks (RRs) of total mortality were 1.41 [95% confidence interval (CI) 1.29–1.53] for obese (BMI >30.0), 1.07 (95 CI 1.02–1.12) for overweight (BMI 25.0–<30.0) and 1.10 (95% CI 0.92–1.31) for underweight (BMI <18.5) women. For obese women, the summary RRs were 1.75 (95% CI 1.26–2.41) for pre-menopausal and 1.34 (95% CI 1.18–1.53) for post-menopausal breast cancer. For each 5 kg/m2 increment of BMI before, <12 months after, and ≥12 months after diagnosis, increased risks of 17%, 11%, and 8% for total mortality, and 18%, 14%, and 29% for breast cancer mortality were observed, respectively.
Obesity is associated with poorer overall and breast cancer survival in pre- and post-menopausal breast cancer, regardless of when BMI is ascertained. Being overweight is also related to a higher risk of mortality. Randomised clinical trials are needed to test interventions for weight loss and maintenance on survival in women with breast cancer.