Prognosis Of Pregnancy-Associated Breast Cancer Based On Propensity Score Matching

Objective:To compare the clinicopathological features and prognosis of pregnancy-associated breast cancer(PABC)and non-pregnancyassociated breast cancer(non-PABC).Methods:The clinical and pathological data of 35 patients with PABC and1086 patients with non-PABC were retrospectively analyzed,and the differences in clinicopathological characteristics between the two groups were compared.Kaplan-Meier survival curve and Log-Rank test were applied to compare the differences in disease-free survival(DFS)and overall survival(OS)between the two groups,and cox proportional hazards regression model was performed to analyze the effect of PABC on DFS and OS of patients.Each patient of the BCP group was matched to 3 corresponding patients in the non-BCP group using propensity score matching(PSM),and the matching variables were the clinicopathological characteristics included.After PSM,28 patients with PABC and 84 patients with non-PABC were obtained.To compare DFS and OS differences between the two groups after matching.Results:(1)There were statistically significant differences in many clinicopathological features between PABC and non-PABC.Patients in the PABC group had a lower median age at diagnosis(P < 0.001),had higher histological tumor grade(P = 0.003),higher tumor stage(P =0.014),and larger tumor size(P < 0.001).The most common molecular type in the PABC group was triple negative breast cancer(31.2%),while the most common in the non-PABC group was luminal B(HER-2negative)type(34%).In terms of immunohistochemical molecular expression,the PABC tumor were often without expression of ER(48.6%vs 77.4%,P < 0.001)and PR(51.4% vs 73.3%,P = 0.008),and had a higher Ki-67 rate(82.8% vs 62.5%,P = 0.042),while HER-2 expression was similar between the two(32.4% vs 23%,P = 0.29).There was no difference in surgical treatment between the PABC group and the non-PABC group,and neoadjuvant chemotherapy(42.9% vs 19.6%,P =0.02),adjuvant chemotherapy(57.1% vs 73.7%,P = 0.048),radiotherapy(80% vs 59%,P = 0.021),and endocrine therapy(57.1% vs 76.9,P =0.012)were applied for the PABC and non-PABC groups,respectively.(2)Patients with PABC had a lower DFS(P=0.011)and OS(P=0.038)compared to controls.Multivariate analysis showed that age(HR: 0.898,95% CI [0.857 – 0.941],P < 0.001),T stage,N stage,and Ki-67(HR: 2.097,95% CI [1.191 – 3.691],P = 0.010)were independent risk factors affecting DFS,while PABC(HR: 1.385,95% CI [0.597 –3.214],P = 0.449)was not;Age(HR: 0.918,95% CI [0.857 – 0.984],P =0.016),T stage,and N stage were independent risk factors affecting OS,while PABC(HR: 1.467,95% CI [0.469 – 4.588],P = 0.510)was not.(3)There was no significant difference in clinicopathological features between 28 PABC patients and 84 non-PABC patients after PSM,and neither did we a find a difference in DFS and OS between the two groups.Conclusion:(1)PABC tumor had poor clinicopathological features,and a diagnosis of PABC was associated with worse DFS and OS of patients.(2)There was no significant difference in the prognosis between PABC and non-PABC with similar clinicopathologic features.