Comparison of Survival After Breast-Conserving Therapy vs Mastectomy Among Patients With or Without the BRCA1/2 Variant in a Large Series of Unselected Chinese Patients With Breast Cancer

Importance

Whether patients with breast cancer who carry aBRCA1/2variant can safely undergo breast-conserving therapy (BCT) remains controversial.

Objective

To compare survival rates after BCT vs mastectomy inBRCA1/2variant carriers and noncarriers in a large series of unselected patients with breast cancer.

Design, Setting, and Participants

In this cohort study, a large consecutive series of 8396 unselected patients with primary breast cancer underwent either BCT, mastectomy with radiotherapy, or mastectomy alone from October 1, 2003, to May 31, 2015, at the Breast Center of Peking University Cancer Hospital in China. All patients were assessed forBRCA1/2germline variant status. Statistical analysis was performed from May 1 to September 30, 2020.

Main Outcomes and Measures

The primary outcomes were breast cancer–specific survival (BCSS) and overall survival (OS); secondary outcomes included recurrence-free survival, distant recurrence–free survival, and ipsilateral breast tumor recurrence.

Results

Of these 8396 Chinese patients (8378 women [99.8% women]; mean [SD] age, 50.8 [11.4] years; 187BRCA1carriers, 304BRCA2carriers, and 7905 noncarriers), 3135 (37.3%) received BCT, 1511 (18.0%) received mastectomy with radiotherapy, and 3750 (44.7%) received mastectomy alone. After a median follow-up of 7.5 years (range, 0.3-16.6 years), bothBRCA1andBRCA2variant carriers treated with BCT had similar rates of survival compared with those treated with mastectomy with radiotherapy (BCSS: hazard ratio [HR] forBRCA1, 0.58 [95% CI, 0.16-2.10];P = .41; HR forBRCA2, 0.46 [95% CI, 0.15-1.41];P = .17; OS: HR forBRCA1, 0.61 [95% CI, 0.18-2.12];P = .44; HR forBRCA2, 0.72 [95% CI, 0.26-1.96];P = .52) or mastectomy alone (BCSS: HR forBRCA1, 0.70 [95% CI, 0.22-2.20];P = .54; HR forBRCA2, 0.59 [95% CI, 0.18-1.93];P = .39; OS: HR forBRCA1, 0.77 [95% CI, 0.27-2.21];P = .63; HR forBRCA2, 0.62 [95% CI, 0.22-1.73];P = .37) after adjusting for clinicopathologic factors and adjuvant therapy. For noncarriers, patients receiving BCT had significantly better survival than those receiving mastectomy with radiotherapy (BCSS: HR, 0.45 [95% CI, 0.36-0.57];P < .001; OS: HR, 0.46 [95% CI, 0.37-0.58];P < .001) or mastectomy alone (BCSS: HR, 0.71 [95% CI, 0.57-0.89];P = .003; OS: HR, 0.71 [95% CI, 0.58-0.87];P < .001) in multivariable analyses.

Conclusions and Relevance

This study suggests thatBRCA1/2variant carriers treated with BCT have survival rates at least comparable to those treated with mastectomy with radiotherapy or mastectomy alone and that BCT could be an option forBRCA1/2variant carriers when the tumor is clinically appropriate for BCT.