Abstract
OBJECTIVE: Breast-conserving therapy (BCT) includes breast-conserving surgery (BCS) combined with radiation therapy (RT). RT plays a crucial role in improving the prognosis of patients who undergo BCS. However, obesity is a potential risk factor for resistance to radiation. The aim of this study was to evaluate any difference in the long-term prognosis of patients with early stage breast cancer and obesity treated with BCT or total mastectomy (TM). DESIGN, SETTING AND PARTICIPANTS: This was a retrospective cohort study involving 1125 patients diagnosed with early stage breast cancer and obesity at the Shanghai Cancer Center of Fudan University from 2013 to 2016. OUTCOME MEASURES: Obesity in the Chinese population was defined as a body mass index ≥28 kg/m(2). Surgical options included BCT and TM. The primary survival outcomes were overall survival (OS), disease-free survival (DFS) and recurrence-free survival (RFS). Inverse probability of treatment weighting (IPTW) was used to control for the impact of confounding factors on prognosis. RESULTS: The median follow-up times in the BCT group and TM group without postoperative RT were 51.1 months (IQR of 40.6-68.1 months) and 61.8 months (IQR of 46.5-76.7 months), respectively. After IPTW, the baseline data were balanced. Compared with those in the TM cohort, patients in the whole IPTW cohort in the BCT cohort had worse DFS (HR 4.280, 95% CI 2.180 to 8.400; p<0.001), RFS (HR 4.380, 95% CI 2.370 to 8.120; p<0.001) and OS (HR 3.590, 95% CI 1.620 to 7.950; p=0.002). CONCLUSION: In patients with early stage breast cancer and obesity, TM is associated with better survival outcomes than BCT.