Determinants of newly diagnosed comorbidities among breast cancer survivors

Purpose Comorbid conditions have become increasingly relevant for breast cancer care given the large numbers of long-term survivors. Our aim was to identify potential determinants associated with the development of comorbidities after breast cancer. Methods Self-reported comorbidities and lifestyle were assessed at recruitment and after a median follow up of 69.4 months from diagnosis in a population-based cohort of breast cancer cases aged 50 to 74 years at diagnosis (MARIEplus study). Tumor and therapy data were extracted from medical records. Determinants potentially associated with incident diagnoses of hypertension, cardiovascular diseases (CVD), and osteoporosis were assessed using multivariable Cox proportional hazard regression models. Results Follow-up interview was completed by 2,542 women (76.4 % of eligible patients). A diagnosis of hypertension was significantly associated with age, higher education (hazard ratio (HR) 0.54, CI 0.37–0.79), baseline body mass index (BMI; ≥30 kg/m 2 ; HR, 1.90; CI, 1.24–2.90), and trastuzumab medication (HR, 2.16; CI, 1.09–4.33). An increased risk for CVD was associated with age, BMI, and intake of aromatase inhibitors (AI; HR, 1.42; CI, 1.09–1.84). Risk of osteoporosis was also positively associated with AI treatment (HR, 2.15; CI, 1.64–2.82) but inversely associated with a higher BMI (≥30 kg/m 2 ; HR, 0.50; CI, 0.31–0.79). Conclusion In breast cancer survivors, treatment with AI constituted a risk factor for incident CVD and osteoporosis. Besides known risk factors, patients who were treated with trastuzumab may have an increased risk for hypertension. Implications for cancer survivors Reducing overweight and regular sport/cycling activities may help to prevent CVD after breast cancer. Patients should be monitored for risk factors and advised on possible cardiac side effects of AI and trastuzumab.