Impact of BRCA1/2 germline mutation on the incidence of second primary cancer following postoperative radiotherapy in patients with triple-negative breast cancer / 中国癌症杂志

ABSTRACT

Background and purpose:BRCA1/2 plays an important role in maintaining the genome stability.Whether BRCA1/2 germline mutation could increase the tumor sensitivity to radiotherapy,thereby inducing secondary primary cancer after radiotherapy is unclear.This study aimed to investigate whether postoperative radiotherapy is a risk factor for the development of second primary cancer in triple-negative breast cancer(TNBC)patients with BRCA1/2 germline mutation.Methods:This research was based on a previously reported retrospective cohort,i.e.,the Fudan University Shanghai Cancer Center TNBC cohort.Between January 1,2007 and December 31,2014,a total of 292 female TNBC patients with BRCA1/2 mutation were enrolled.We performed logistic regression analysis in patients without BRCA1/2 germline mutation(n=261)and BRCA1/2 germline mutation patients(n=31),respectively,to assess the risk factors affecting the incidence of second primary cancer.We then performed interactive analysis on the above two analyses to evaluate the interactive effect between BRCA1/2 germline mutation and postoperative radiotherapy.P<0.05 indicates a statistically significant difference.The research was approved by Fudan University Shanghai Cancer Center TNBC Ethics Committee(050432-4-2108),and each patient provided written informed consent.Results:Logistic regression analysis in patients with BRCA1/2 germline mutations showed that postoperative radiotherapy significantly increased the risk of secondary primary disease compared to non-radiotherapy[odds ratio(OR)=2.475,95%confidence interval(CI):1.933-3.167,P<0.001].In patients without BRCA1/2 germline mutation,the effect of radiotherapy on the incidence of second primary tumor was not significant.There was a significant interaction between BRCA1/2 germline mutation and postoperative radiotherapy for the incidence of secondary primary cancer(OR=9.710,95%CI:0.320-295.250,P=0.193).Conclusion:Although statistical analysis results show that patients with BRCA1/2 germline mutations have an increased risk of developing a second primary tumor after postoperative radiotherapy compared to patients who have not received radiotherapy,there is no significant correlation between BRCA1/2 germline mutations and radiotherapy for the development of a second primary tumor.Therefore,patients with BRCA1/2 germline mutations who receive radiotherapy after surgery may not increase the risk of developing a second primary tumor.