Mucinous Breast Carcinoma: Occult Multifocality/Multicentricity in a Favorable Disease.

Abstract

Abstract Purpose: Mucinous carcinoma is a distinctive tumor that reportedly has a very favorable prognosis. Accordingly, investigators have recommended that patients be treated with minimal effective therapy rather than maximum tolerated treatment. However, previous reports have been limited by small sample sizes and very short follow-up intervals. We have previously reported outcomes for a mature data set with long term follow-up and now perform the current analysis to emphasize comprehensive multidisciplinary management in an era of minimal effective therapy for so-called favorable disease.Methods and Materials: We retrospectively reviewed charts for 264 patients with a pure mucinous carcinoma diagnosis at our institution from 1965-2005. Multidisciplinary management is emphasized for all patients at our institution including this patient cohort. All pathology was centrally reviewed. Overall survival, DM-free survival, and local-regional control were compared using Kaplan Meier method and log rank statistics.Results: Median age was 57 years (range 25-89). Median follow-up was 168 months. 86% of patients were stage T2 or less. Patients who were lymph node negative compared with 1-3 LN+, or 4 or more LN+ were 80%, 15%, and 5% respectively. 44% received BCT while the remainder underwent mastectomy. 51% of all patients received XRT. No patient in this cohort received partial breast irradiation. 10% of patients had an initial multicentric/multifocal presentation. However, a detailed pathology review revealed a 38% multifocal/multicentric disease rate after surgical resection. The occult tumors were not initially detected by mammography or ultrasonography.5, 10, and 15 year OS, DMFS, and LRC rates for all patients were: 95%/88%/83%; 97%/95%/92%; and 97%/94%/85% respectively. There was no statistically significant difference in OS, DMFS, or LRC based upon surgical management by mastectomy in comparison with BCT. Likewise, there was no statistically significant improvement in OS or DMFS with utilization of whole breast XRT. There was, however, a trend for improved LRC in patients who received XRT (p=0.06) in comparison with patients who underwent mastectomy or BCT without XRT.Conclusions: This large series of patients diagnosed with pure mucinous breast carcinoma demonstrates potentially favorable prognosis. However, this is the first known report of an association with significant occult multicentricity/multifocality. In an era of minimal effective cancer therapy which includes no additional treatment post resection in favorable histology, and partial breast XRT in favorable histology, multidisciplinary management inclusive of pathology and diagnostic imaging is recommended. Current treatment guidelines should reflect that before omitting whole breast XRT, patients should have pathologic and radiologic intraoperative correlation and MRI should be a consideration in efforts to identify potential occult disease. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4117.