The impact of body size changes on recurrence risk depends on age and estrogen receptor status in primary breast cancer

Purpose: To investigate the prognostic impact of body size changes during the first postoperative year in breast cancer.

Methods: A cohort of 1,317 primary breast cancer patients included in Sweden (2002-2014) underwent body size measurements at the preoperative and 1-year visits (n = 1,178). Landmark survival analyses were used to investigate how postoperative weight gain or loss (> 5%) or change in waist-hip ratio (WHR) categories (≤ 0.85 or > 0.85) impact prognosis.

Results: Median age at inclusion was 61 years and body mass index 25.1 kg/m². After a median follow-up of 5.0 years from inclusion, 165 recurrences and 77 deaths occurred. Weight gain (17.0%) conferred over twofold recurrence risk only in patients < 50 years (P_interaction = 0.033). Weight loss (8.6%) was only associated with a poor prognosis in patients ≥ 70 years, but not after restriction analysis. Weight change did not impact prognosis in patients 50 to < 70 years. Changes between WHR categories were associated with differential recurrence risk depending on estrogen receptor (ER) status (P_interaction = 0.007), with higher recurrence risk in patients with ER+ tumors and lower recurrence risk with ER- tumors.

Conclusion: Both changes in terms of weight and WHR category yielded independent prognostic information. Further research is imperative before recommending weight loss for all overweight breast cancer patients.