Pathological features of mucinous carcinoma of the breast are favourable for breast-conserving therapy

Aim: The effectiveness of breast-conserving therapy for mucinous carcinoma has not been well documented. We examined clinical and pathological features of cases to determine whether patients with mucinous carcinoma were suitable candidates for this treatment. Method: Cases of pure type (n=52) and mixed type (n=24) mucinous carcinomas were reviewed with emphasis on the risk factors associated with local recurrences after breast-conserving therapy. Results: Large pure mucinous carcinomas had a low incidence of extensive intraductal spreading (EIS). An inverse correlation existed between the incidence of EIS and tumour size (P<0.05). Comedo type EIS was infrequent (11%) in pure mucinous carcinoma. Incidences of lymphatic vessel invasion (4%) and nodal involvement (4%) were lower in pure mucinous carcinoma than in mixed carcinoma (P<0.05). No nodal involvement occurred in patients with pure mucinous carcinoma less than 3 cm in diameter. Conclusions: Patients with pure mucinous carcinomas, except those invading the local skin, are suitable candidates for breast-conserving therapy. Most pure mucinous carcinomas, including a large tumour up to 5 cm in diameter, can be treated with this therapy.