Analysis Of Clinicopathological Features And Prognostic Factors Of Second Breast Cancer Patients With Double Primary Cancers

Background and Objective:Breast cancer is not only the most common type of malignancy tumor but is also one of the major causes of cancer-related deaths among women all over the world.Most of the foreign and domestic studies have aimed at breast cancer as first primary cancer(FPC),bilateral primary breast cancer(BPBC),double primary cancers(DPC)involving breast cancer in recent years,however,fewer researchers only focus on patients with breast cancer as second primary cancer(SPC).The objective of this study was to discuss the clinicopathological features and prognostic factors of such a population.It was hoped that this study could be taken as a kind of replenish of the studies of double primary cancers involving breast cancer and could be a reference for medical practice.Methods:Utilizing the Surveillance,Epidemiology,and End Results(SEER)Program in the United States,we retrospectively analyzed clinical data of pathologically-proved second primary breast cancer(SPBC)patients with double primary cancers from 2010 to 2015 collected from SEER and the patients were divided into two groups-the synchronous double primary cancers(SDPC)group and the metachronous double primary cancers(MDPC)group-based on whether the interval between FPC and SPC was short of six months.We analyzed the difference of the clinicopathological features and the prognosis between both groups.The influential factors for prognosis were determined by univariate and multivariate Cox proportional hazard regression models.Then prognostic factors were utilized to develop a nomogram and then we used the concordance index(C-index)to measure its predictive accuracy.The measurement data was expressed as mean±standard deviation,the enumeration data was expressed as frequency or rate.Chi-square test was adopted in univariate analysis of clinicopathological features and univariate and multivariate Cox proportional hazard regression models were applied in the analysis of potential prognostic factors.Kaplan-Meier method was utilized to draw the survival curve,and Log-Rank test was adopted for survival analysis.When P<0.05,the difference was of statistical significance.Results:The differences of FPC type,clinicopathological features of SPBC(age,primary site,pathological type,histologic grade,surgery,T classification,N classification,radiotherapy,chemotherapy,estrogen receptor(ER)status,progesterone receptor(PR)status,human epidermal growth factor receptor 2(HER-2)status,marital status at diagnosis)between the SDPC group and the MDPC group were statistically significant,while at the same time there was no statistically striking difference of race and laterality between both groups.We utilized propensity score matching(PSM)to eliminate the differences of clinicopathological features between both groups,and then found out the fact that there was no striking difference of survival curves(P=0.61)while the difference was statistically significant before PSM(P<0.0001).The result reflected that age,race,primary site,histologic grade,T classification,N classification,radiotherapy,ER status,PR status,marital status at diagnosis and FPC type were predictive factors for second breast cancer patients with double primary cancers.Risk factors included age older than 75,the black race,FPC located in lung,primary site located in axillary tail of breast,ER-negative status and PR-negative status while at the same time protective factors included radiotherapy.Age,race,FPC type,primary site,histologic grade,T classification,N classification,radiotherapy,ER status,PR status,marital status at diagnosis,chemotherapy and HER-2 status were taken into the construction of a nomogram for predicting the 1-year,3-year,and 5-year survival.The C-index value for the training set and the validation set of the nomogram was 0.758[95%CI:(0.699,0.817)]and 0.760[95%CI:(0.666,0.854)],respectively.The calibration curves showed that the nomogram could be a reliable tool for accurate prognostic prediction in second breast cancer patients with double primary cancers.Conclusion:1.The differences of FPC type,clinicopathological features of SPBC(age,primary site,pathological type,histologic grade,surgery,T classification,N classification,radiotherapy,chemotherapy,ER status,PR status,HER-2 status,marital status at diagnosis)between the SDPC group and the MDPC group were statistically significant.There was no striking difference of survival curves between the SDPC group and the MDPC group after PSM.2.Age,race,primary site,histologic grade,T classification,N classification,radiotherapy,ER status,PR status,marital status at diagnosis and FPC type were predictive factors for second breast cancer patients with double primary cancers.Risk factors included age older than 75,the black race,FPC located in lung,primary site located in axillary tail of breast,ER-negative status and PR-negative status while at the same time protective factors included radiotherapy.3.The proposed nomogram could be a reliable tool for accurate prognostic prediction in second breast cancer patients with double primary cancers.