Role Of Adjuvant Radiotherapy For Primary Breast Diffuse Large B-cell Lymphoma

ObjectiveThe impact of radiotherapy(RT)after chemotherapy in primary breast diffuse large B-cell lymphoma(PB-DLBCL)is controversial.We aimed to determine the risk factors for Cancer-Specific Survival(CSS)among these patients and to develop a risk‐stratification system to identify which of these patients would benefit from RT.Methods and MaterialsBased on the Surveillance,Epidemiology and End Results(SEER)database(2001–2016),patients pathological diagnosed as primary breast diffuse large B-cell lymphoma were enrolled.Screening of prognostic factors and determining risk factors were accomplished by the Cox proportional hazards model.Survival was compared by Kaplan-Meier and Log-rank test.Baseline covariates were balanced by a propensity score model.The endpoint was CSS.ResultsA total of 847 cases were reviewed,and after the exclusion,finally,560 patients were identified from the SEER database.Median follow up time was 96.2 months(24.3-170.4 months).The 5 year-CSS was 74.38% for the whole cohort.Age,marital status,Lymphoma-Ann Arbor stage,radiotherapy,and chemotherapy were associated with CSS by univariate analysis.Multivariate analysis showed that age>60 years,absence of chemotherapy,absence of radiotherapy,Ann-Arbor stage Ⅲ-Ⅳ and marital status(“single/never married/widow/divorced /unknown”)predicted poor CSS.After carried out subgroup analysis,the 5-year CSS was significantly superior for stage Ⅰ-Ⅱ patients who received RT compared to those who did not receive RT (85.05% vs.72.80%,P<0.001).A risk‐stratification system composed of age,chemotherapy and Ann-Arbor stage was generated.Low‐risk patients(score ≤ 2.5)had better CSS than high‐risk(score > 2.5)patients(87.760% vs.73.35%,P < 0.001).The addition of radiotherapy enhanced the CSS among the high‐risk patients(58.18%vs 79.61%,P < 0.001)but produced no survival benefit among the low‐risk patients(85.09% vs.87.51%,P=0.425).After propensity score-matched(PSM)analysis,we found that compared with chemotherapy alone,chemotherapy plus radiation can improve 5-year CSS of PB-DLBCL patients(88.59% vs.78.67%,P = 0.024).ConclusionsOur risk‐stratification model based on age,Ann-Arbor stage,and chemotherapy record predicted the outcomes of PB-DLBCL patients.In conclusion,this risk-stratification model may be helpful to identify patients who may benefit from RT.And our study suggests that chemotherapy plus RT still added significant therapeutic benefits for PB-DLBCL patients.