Pure and mixed mucinous carcinomas of the breast: a clinicopathologic analysis of 61 cases with long-term follow-up.

Sixty-one mucinous carcinomas (MCs) of the female breast were followed-up for at least 18 years or until death (mean follow-up time, 26 years; median follow-up time, 23 years). The 61 MCs were compared with 441 unselected cases of breast carcinomas of all histologic types (reference carcinomas or RCs), which were follow-up for at least 21 years. When the MCs were divided into pure (PMCs) and mixed (MMCs) mucinous carcinomas, the 20-year cumulative corrected survival rate for operable cases in the PMC group was 79% +/- 11% (SE) and 28% +/- 13% for the MMC group. The difference is statistically significant (P less than .001). The PMCs had a significantly better survival rate (P less than .001) when compared with the RCs (20-year corrected survival rate, 41% +/- 3%). The survival rates for the MMCs and RCs did not differ significantly from each other. By Cox's multivariate analysis, pure histologic type and a tumor size less than 5cm were independent favorable prognostic factors in the MC group, but nodal status was closely related to the histologic type. Judging from the relative survival curves, no significant excess mortality of cancer occurred toward the end of the follow-up period in the PMC group.