Breast‑conserving therapy versus mastectomy in malignant phyllodes tumor of the breast: a propensity score-matched survival analysis and prognostic nomogram.

UNLABELLED: Malignant phyllodes tumor of the breast (MPTB) is rare but aggressive fibroepithelial neoplasms. This study aimed to compare long-term survival outcomes between Breast-conserving therapy (BCT) and mastectomy in patients with stage T1‑3N0M0 MPTB and to develop a prognostic nomogram.

METHODS

We identified 683 female patients with stage T1‑3N0M0 MPTB from the SEER database (2010‑2017). Overall survival (OS) and breast cancer‑specific survival (BCSS) were analyzed using Kaplan‑Meier and Cox regression. A nomogram predicting 3‑ and 5‑year OS was constructed and validated.

RESULTS

After matching, 282 patients remained in each group. In unadjusted Kaplan‑Meier analysis, BCT was associated with significantly better BCSS (P = 0.0048) and OS (P = 0.017) compared with mastectomy. However, multivariate Cox regression revealed that BCT was not an independent predictor of BCSS (P = 0.355) or OS (P = 0.789). Independent adverse prognostic factors for OS included age ≥ 50 years and T3 stage. The nomogram showed moderate discrimination, with a C‑index of 0.706 (95% CI: 0.524-0.888) in the training cohort and 0.764 (95% CI: 0.543-0.984) in the validation cohort. Although overall prediction error was low in both cohorts, calibration drift was observed in the validation cohort.

CONCLUSIONS

After adjusting for confounding factors, BCT was not independently associated with inferior long-term survival compared with mastectomy. When negative margins can be achieved, BCT is a reasonable surgical option. The proposed nomogram may assist in individualized risk assessment, but requires further external validation before clinical implementation.