Dermal lymphatic invasion and inflammatory breast cancer are independent predictors of outcome after postmastectomy radiation

Objectives: Inflammatory breast cancer (IBC) is a clinical staging based on history and physical findings. Dermal lymphatic invasion (DLI) can occur with or without IBC. We examine how these independently affect outcome in women treated with postmastectomy radiation. Methods: Four hundred thirty-two patients treated with postmastectomy radiation for invasive mammary cancer were assessed. Kaplan-Meier methodology was used to calculate rates of locoregional recurrence (LRR), distant metastases (DM) and overall survival (OS). Variables entered into univariate and multivariate analysis included T stage, IBC, DLI, estrogen receptor/progesterone receptor status, HER-2/neu status, N stage, extracapsular node extension (ECE), and use of chemotherapy (CT). Median follow-up is 58 months. Results: For all 432 patients, the rate of LRR was 3% and DM 28%. Seven percent are alive with disease (AWD) and 26% are dead of disease (DOD). Thirty-one patients had IBC without DLI, 21 had DLI without IBC, and 18 had both IBC and DLL For DLI 10% developed LRR, 45% DM, 7.5% are AWD and 50% are DOD. Of patients with IBC, 8% developed LRR, 44% DM, 8% are AWD and 48% DOD. DLI was the only significant independent predictor for LRR (HR 4.8, P < 0.05). Predictors of DM and OS were IBC, ≥4 positive nodes, and CT. Conclusions: DLI and IBC are independent predictors of poor outcome after postmastectomy radiation. DLI is associated with an increased risk for LRR, and IBC with worse rates of DM and OS. Patients with both features have worse outcome than those with either alone.