Impact of postoperative radiotherapy on the relationship between molecular subtype and prognosis in patients with breast cancer / 中华放射肿瘤学杂志

ABSTRACT

Objective To retrospectively investigate the impact of postoperative radiotherapy ( RT) on the relationship between molecular subtype and survival in patients with breast cancer ( BC ) . Methods A total of 716 women who were admitted to our hospital in 2008 and newly received unilateral mastectomy were divided into Luminal A ( LA ) , Luminal B?HER?2?negative ( LB1 ) , Luminal B?HER?2?positive ( LB2) , HER?2 overexpression ( HER?2+) , triple?negative ( TN) , and unassigned subtypes according to the 2011 St. Gallen Consensus. The Cox model was used to analyze the differences in overall survival ( OS) and disease?free survival ( DFS ) rates between subtypes in all patients, RT group, or non?RT group. The Kaplan?Meier method was used to calculate OS and DFS rates. The Cox model was used to perform the factor analysis. Results In all patients, the median follow?up time was 71?4 months;the overall mortality rate was 10?5%;the incidence of treatment failure ( death+relapse+metastasis) was 14?9%;217 patients ( 30?3%) received RT. The multivariate analysis showed that there was no significant difference in OS between subtypes in any group ( all P>0?05 ) . In all patients, patients with LB1 subtype or unassigned subtype had significantly poorer DFS rates than those with LA subtype ( HR= 1?881, P= 0?035;HR= 1?907, P=0?049) . In the non?RT group, patients with LB1 subtype had significantly poorer DFS rates than those with LA subtype (HR=3?324, P=0?01). In the RT group, there was no significant difference in DFS rate between subtypes ( all P>0?05) . The two?dimensional cross analyses of RT and subtype demonstrated that patients with LB1 subtype in the non?RT group had lower OS and DFS rates than patients with LA subtype in the RT group ( P=0?09,0?06) . Conclusions Patients with LB1 subtype have lower OS and DFS rates than patients with LA subtype, especially in the non?RT patients. RT has no impact on the relationship between subtype and prognosis.