OBJECTIVETo report the clinical and pathological characteristics of bilateral primary breast cancer (BPBC) in comparison with unilateral primary breast cancer (UPBC).

METHODSA retrospect database of primary breast cancer patients admitted to the Cancer Hospital from March 1967 through May 2003 was analyzed.

RESULTSA total of 10,470 primary breast cancer patients were treated, among which 271 patients had bilateral primary tumors with an incidence of 2.1%. Most of the BPBC, developed both synchronously (sBPBC, incidence rate: 0.6%) and metachronously (mBPBC, incidence rate: 1.5%), were diagnosed in premenopausal women with an average age of 48. In the latter cases, the median time interval between their occurrences was 57.6 months. The median survival time for patients with sBPBC and mBPBC was 29.6 months and 27.8 months, respectively. There was no statistical difference in survival rate between the 2 groups of patients. Nor was menopausal status related to survival. In mBPBC patients, when the occurrence of the second breast cancer was taken as the beginning of prognostic analysis, the prognosis of BPBC patients was worse than those with unilateral involvement.

CONCLUSIONPrognosis of patients with bilateral primary breast cancer is poor. In mBPBC patients whose breast cancers appear one after the other, meticulous follow-up is needed after resection of tumor on one side to early detect development of cancer of the countralateral breast especially within 5 years.