Malignant phyllodes tumor of the female breast: association of primary therapy with cause-specific survival from the Surveillance, Epidemiology, and End Results (SEER) program.

Background: Malignant phyllodes tumor is a rare and potentially aggressive breast neoplasm. Little information is available regarding the optimal management of these lesions and rarer still are data regarding survival. The current study used a large population database to determine prognostic factors that predict cause-specific survival (CSS).

Methods: Data were obtained from the Surveillance, Epidemiology, and End Results Program (SEER) for the years 1983-2002. Women receiving resection for primary nonmetastatic malignant phyllodes tumor of the breast were included (n = 821). Analyses of patient, pathologic, and treatment characteristics were performed using univariate and multivariate Cox regression analyses for the CSS endpoint.

Results: With a median follow-up of 5.7 years, CSS was 91%, 89%, and 89%, at 5, 10, and 15 years, respectively. Mastectomy was performed in 428 women (52%) and wide excision or lumpectomy in 393 (48%). Women undergoing mastectomy were significantly older (P = .004) and had larger tumors (P = .009). Wide excision was associated with equivalent or improved CSS relative to mastectomy on univariate and multivariate analyses. Older age predicted for cause-specific mortality on multivariate analysis. Adjuvant radiotherapy (RT) predicted for worse CSS when implemented compared with surgery alone.

Conclusions: Mastectomy was not found to provide a benefit in CSS compared with wide excision in malignant phyllodes tumor of the breast. Women undergoing wide excision had at the minimum similar cancer-specific mortality compared with those who received mastectomy. The role of adjuvant RT is uncertain and requires further investigation.