Wu SG, et al. - In this study, researchers determined the clinical value of postoperative radiotherapy (PORT) in invasive micropapillary carcinoma (IMPC) of the breast. As per observations, IMPC seemed to have favorable breast cancer-specific survival (BCSS) and OS. PORT groups were not inferior to non-PORT groups on BCSS and OS. This was regardless of the types of surgical procedures (mastectomy or breast-conserving surgery).

Methods

• Clinicopathological factors extracted from the Surveillance, Epidemiology, and End Results database (2004–2013) were assessed.
• Researchers performed univariate and multivariate Cox proportional hazards regressions to assess the independent prognostic factors on breast cancer-specific survival (BCSS) and overall survival (OS).

Results

• This study included 881 patients.
• 444 (50.4%) and 437 (49.6%) underwent breast-conserving surgery (BCS) and mastectomy (MAST), respectively, of whom 357 (80.4%) and 153 (35.0%) underwent PORT, respectively.
• Patients with young age, large tumor size, or advanced nodal stage more frequently underwent MAST and PORT compared with MAST alone.
• Patients with progesterone receptor-positive disease more frequently received BCS and PORT compared with BCS alone.
• In this study, the 5-year BCSS and OS were 95.7% and 90.9%, respectively.
• Multivariate analyses suggested that tumor size, histological grade, and estrogen receptor status were independent predictors of BCSS and OS.
• The type of surgical procedures (MAST vs. BCS) seemed not an independent predictor of survival outcomes.
• As per multivariate analyses, patients who underwent MAST with or without PORT were similar in terms of BCSS and OS.
• In comparison to those who underwent BCS alone, patients undergoing BCS plus PORT indicated no better outcome regarding BCSS and OS.
• In the low-, intermediate-, and high-risk groups, PORT seemed not related with better BCSS and OS than non-PORT groups in patients who received BCS or MAST.