Clinicopathologic characteristics of pregnancy-associated breast cancer: Results of analysis of a nationwide breast cancer registry database

Purpose: This study aimed to evaluate the clinicopathological characteristics of pregnancy-associated breast cancer (PABC) in comparison with non-pregnancy associated breast cancer (non-PABC). Methods: A total of 344 eligible patients with PABC were identified in the Korean Breast Cancer Society Registry database. PABC was defined as ductal carcinoma in situ, invasive ductal carcinoma, or invasive lobular carcinoma diagnosed during pregnancy or within 1 year after the birth of a child. Patients with non-PABC were selected from the same database using a 1:2 matching method. The matching variables were operation, age, and initial stage. Results: Patients with PABC had significantly lower survival rates than patient with non-PABC (10-year survival rate: PABC, 76.4%; non-PABC, 85.1%; p= 0.011). PABC patients had higher histologic grade and were more frequently hormone receptor negative than non-PABC patients. Being overweight (body mass index [BMI], ≥23 kg/m²), early menarche (≤13 years), late age at first childbirth (≥30 years), and a family history of breast cancer were more common in the PABC group than in the non-PABC group. Multivariate analysis showed the following factors to be significantly associated with PABC (vs. non-PABC): early menarche (odds ratio [OR], 2.165; 95% confidence interval [CI], 1.566−2.994; p<0.001), late age at first childbirth (OR, 2.446; 95% CI, 1.722−3.473; p< 0.001), and being overweight (OR, 1.389; 95% CI, 1.007−1.917; p= 0.045). Conclusion: Early menarche, late age at first childbirth, and BMI ≥ 23 kg/m² were more associated with PABC than non-PABC.