Association of pre‐diagnosis physical activity with recurrence and mortality among women with breast cancer

• Published in: International journal of cancer Vol. 133; no. 6; pp. 1431 - 1440
• Main Authors: Schmidt, Martina E., Chang‐Claude, Jenny, Vrieling, Alina, Seibold, Petra, Heinz, Judith, Obi, Nadia, Flesch‐Janys, Dieter, Steindorf, Karen
• Format: Journal Article
• Language: English
• Published: Hoboken, NJ Wiley-Blackwell 15-09-2013; Wiley Subscription Services, Inc
• Subjects: Aged; Analysis; Biological and medical sciences; Breast cancer; Breast Neoplasms - chemistry; Breast Neoplasms - mortality; Cancer; Cohort Studies; Confidence intervals; Exercise; Female; Gynecology. Andrology. Obstetrics; Humans; Kaplan-Meier Estimate; Mammary gland diseases; Medical research; Medical sciences; Middle Aged; Mortality; Multiple tumors. Solid tumors. Tumors in childhood (general aspects); Neoplasm Recurrence, Local - epidemiology; physical activity; Physical fitness; prognosis; Proportional Hazards Models; Prospective Studies; Receptors, Estrogen - analysis; Receptors, Progesterone - analysis; recurrence; Tumors; Women; Europe; Germany; Human; Physical exercise; Relapse; Breast disease; Prognosis; Mortality; Breast cancer; Malignant tumor; Epidemiology; physical activity; recurrence; Mammary gland diseases; Cancerology; Adult; Female; Public health; Cancer; Life style; mortality; breast cancer; prognosis
• DOI: 10.1002/ijc.28130
• EISSN: 1097-0215
• ISSN: 0020-7136

Evidence is emerging that physical activity (PA) may improve overall survival after breast cancer diagnosis. However, the effect of PA on breast cancer recurrence and on cause‐specific mortality is less investigated. We assessed the association of pre‐diagnosis PA with recurrence, overall and cause‐specific survival in a prospective cohort study in Germany including 3,393 non‐metastatic breast cancer patients aged 50–74 years. Cox proportional hazards models were calculated adjusted for relevant prognostic factors. During a median follow‐up of 5.6 years, 367 patients deceased. Overall mortality was significantly inversely associated with pre‐diagnosis recreational PA. However, this effect was mainly attributed to deaths due to causes other than breast cancer. Multiple fractional polynomial analyses yielded a nonlinear association with markedly increased non‐breast cancer mortality for women who did not engage in any sports or cycling in the years before the breast cancer diagnosis with a hazard ratio (HR, none vs. any) of 1.71, 95% confidence interval (1.16, 2.52). There were no further risk reductions with increasing activity levels. The association with breast cancer‐specific mortality showed a similar dose‐response but was far less pronounced with HR (none vs. any) = 1.22 (0.91, 1.64). In contrast, regarding cancer recurrence the dose‐response was linear. However, this association was restricted to estrogen/progesterone receptor‐negative (ER−/PR−) cases (pinteraction = 0.033) with HR (highest vs. no recreational PA) = 0.53 (0.24, 1.16), ptrend = 0.0045. Thus, breast cancer patients with a physically inactive lifestyle pre‐diagnosis may decease prematurely irrespective of their cancer prognosis. Higher levels of exercise may reduce the risk of recurrence of ER−/PR− breast tumors.
What's new?
Whether pre‐diagnosis physical activity impacts risk of recurrence and mortality from breast cancer has remained unclear, though such associations could have implications for the interpretation of patient outcome. Here, analysis of data on 3,393 nonmetastatic breast cancer patients reveals an inverse association between pre‐diagnosis physical activity and overall mortality, but primarily for instances of death apparently unrelated to breast cancer, such as non‐breast neoplasms and circulatory events. Higher levels of exercise were linked to a reduced risk of disease recurrence among patients with ER‐/PR‐ breast tumors.