title: Association of pre-diagnosis physical activity with recurrence and mortality among women with breast cancer.
abstract: 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 (p interaction = 0.033) with HR (highest vs. no recreational PA) = 0.53 (0.24, 1.16), p trend = 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.
authors: Unit of Physical Activity and Cancer, Division of Environmental Epidemiology, German Cancer Research Center (DKFZ), Heidelberg, Germany. m.schmidt@dkfz.de
authors: Martina E
authors: ME
authors: Schmidt
authors: Jenny
authors: J
authors: Chang-Claude
authors: Alina
authors: A
authors: Vrieling
authors: Petra
authors: P
authors: Seibold
authors: Judith
authors: J
authors: Heinz
authors: Nadia
authors: N
authors: Obi
authors: Dieter
authors: D
authors: Flesch-Janys
authors: Karen
authors: K
authors: Steindorf
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000737:chemistry / Q000401:mortality*; D015331:Cohort Studies; D015444:Exercise; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology*; D016016:Proportional Hazards Models; D011446:Prospective Studies; D011960:Receptors, Estrogen / Q000032:analysis; D011980:Receptors, Progesterone / Q000032:analysis
chemical_list: D011960:Receptors, Estrogen; D011980:Receptors, Progesterone
keywords: breast cancer; mortality; physical activity; prognosis; recurrence