Survival analysis of patients with unilateral and bilateral primary breast cancer in Northeast China

Background Previous reports have shown that patients with bilateral primary breast cancer (BPBC) had comparable or moderately poor survival compared with patients experiencing unilateral primary breast cancer (UPBC). However, studies are conflicting in their analyses of correlations between survival and clinicopathological and prognostic characteristics in BPBC patients. The aim of our study was to compare the clinicopathological features and prognoses of BPBC and UPBC patients in Heilongjiang Province, northeast China. Methods We retrospectively reviewed the records of 2,695 patients who underwent modified radical mastectomy or lumpectomy from 2005 to 2008 in the Tumor Hospital of Harbin Medical University. Eighty-one patients (3.0 %) had BPBC and 2,614 patients had UPBC. Multivariate analysis was performed using Cox's proportional hazards model. Results There were significant differences between patients with BPBC and UPBC in the age of onset (referring to the age when the first tumor in BPBC was diagnosed), T stage, menopause status (referring to the age when the second tumor in BPBC was diagnosed), and breast cancer family history. The overall 5-year survival of patients with BPBC was 70.1 % compared with 87.1 % for patients with UPBC (p = 0.004). Furthermore, multivariate analysis showed that HER-2 status, menopause status, and mammary disease history were significant factors affecting survival among the patients with BPBC. Conclusions Our results confirmed previous findings that BPBC patients had moderately poor survival. However, when T stages were matched, BPBC patients had a survival rate similar to UPBC patients. Premenopause status, HER-2 positivity and family history of breast cancer were major risk factors for BPBC.