Given breast cancer, does breast size matter? Data from a prospective breast cancer cohort

Body mass index (BMI), waist-to-hip ratio (WHR), and tumor characteristics affect disease-free survival. Larger breast size may increase breast cancer risk, but its influence on disease-free survival is unclear. The purpose of this study was to elucidate whether breast size independently influenced disease-free survival in breast cancer patients.

Body measurements were obtained preoperatively from 772 breast cancer patients in a population-based ongoing cohort from southern Sweden. The research nurse measured breast volumes with plastic cups used by plastic surgeons doing breast reductions. Clinical data were obtained from patient charts and pathology reports.

Patients with a BMI ≥ 25 kg/m² had larger tumors (p < 0.001) and more axillary nodal involvement (p = 0.030). Patients with a WHR > 0.85 had larger tumors (p = 0.013), more advanced histological grade (p = 0.0016), and more axillary nodal involvement (p = 0.012). Patients with right + left breast volume ≥ 850 mL were more likely to have larger tumor sizes (p = 0.018), more advanced histological grade (p = 0.031), and more axillary nodal involvement (p = 0.025). There were 62 breast cancer events during the 7-year follow-up. Breast volume ≥ 850 mL was associated with shorter disease-free survival (p = 0.004) and distant metastasis-free survival (p = 0.001) in patients with estrogen receptor (ER)-positive tumors independent of other anthropometric measurements and age. In patients with ER-positive tumors, breast size was an independent predictor of shorter disease-free (HR 3.64; 95 % CI 1.42–9.35) and distant metastasis-free survival (HR 6.33; 95 %CI 1.36–29.43), adjusted for tumor characteristics, BMI, age, and treatment.

A simple and cheap anthropometric measurement with standardized tools may help identify a subgroup of patients in need of tailored breast cancer therapy.