Comparing Survival Differences Between Breast-Conserving Therapy and Mastectomy in Patients with Early-Stage Breast Cancer

Abstract

In 1990 breast-conserving therapy (BCT) was recommended as a preferred treatment for early-stage breast cancer by the NIH consensus statement based on randomized trials demonstrating BCT to have equivalent survival outcomes as mastectomy for early-stage breast cancer patients. BCT became more common while total mastectomy (TM) rates decreased. More recently, patients with early-stage breast cancer are undergoing TM with increasing frequency. In light of increasing TM rates and given significant changes in radiation, surgery and systemic therapies, several groups have examined long-term outcomes for patients undergoing TM vs BCT. Local-regional recurrence (LRR) rates with BCT have been reported to be lower than the 8-10% LRR range reported with the initial randomized trials. In addition, several groups have published slightly improved survival rates in patients undergoing BCT compared with TM. The aim of this study was to evaluate trends in TM rates for treatment of early-stage breast cancer at a single institution and compare overall survival (OS), distant metastasis-free survival (DMFS), LRR and disease-specific survival (DSS) between breast conservation and TM. We identified clinical stage T1–2, N0–1, M0 breast cancer patients who underwent primary surgery from 1/1/2000 to 12/31/2014. TM and BCT rates were evaluated, and multivariable Cox proportional hazards models were used for comparison of survival differences between breast conserving surgery alone (BCS), BCT and TM with or without radiation therapy (RT). Of 12,034 patients included, 800 (6.7%) underwent BCS, 5,986 (49.7%) underwent BCT, 3.618 (30.1%) underwent TM without RT and 1,630 (13.5%) underwent TM with RT. Patients who underwent TM were younger, with more advanced and aggressive disease (larger tumors, positive lymph nodes, higher grade, and more likely to be ER/PR-negative or HER2-positive). TM rates increased over time in patients <=50 years old. At median follow-up time of 6.2 years, multivariable Cox model showed that patients who underwent BCT had a better DSS (HR: 0.8, P=0.02) and OS (HR: 0.7, P<0.001) and had a similar DMFS (HR: 0.9, P=0.3), but had increased LRR (HR: 1.3, P=0.04) compared to patients who underwent TM without RT. In patients undergoing TM with RT, there was no survival benefit found in OS, DSS and DMFS on multivariable analyses compared with patients who underwent BCT. Patients who underwent BCS alone had a worse OS, LRR and DMFS compared to patients undergoing BCT. 5-year LRR and DSS rates were similar between TM without RT and BCT groups. After adjusting for confounding variables, BCT showed improved OS and DSS compared with TM in early-stage breast cancer. These contemporary data may help physicians in surgical decision making for patients who are candidates for either mastectomy or breast conservation since they suggest that BCT is at least equivalent to TM with respect to OS and DSS.