Epidemiology, treatment patterns, and survival outcomes of porocarcinoma: A population-based analysis

Porocarcinoma is a rare malignant adnexal tumor arising from the eccrine sweat gland acrosyringium. The epidemiology, treatment patterns, and prognostic factors for this malignancy remain incompletely characterized due to its extreme rarity. This study aimed to provide a comprehensive population-based analysis of porocarcinoma in the United States. We retrospectively analyzed all porocarcinoma cases (ICD-O-3 code 8409/3) from the Surveillance, Epidemiology, and End Results database diagnosed between 2000 and 2022. Patient demographics, tumor characteristics, treatment modalities, and survival outcomes were examined. Cancer-specific survival (CSS) was estimated using Kaplan-Meier analysis, and prognostic factors were identified through Cox proportional hazards regression. A total of 953 patients were identified, representing the largest population-based porocarcinoma cohort to date. Mean age was 70.2 ± 15.9 years, with male predominance (55.5%). The lower extremity was the most common primary site (32.4%), followed by head/neck (30.5%). The majority presented with localized disease (74.5%), while regional and distant disease accounted for 5.5% and 1.3%, respectively. Surgical treatment was performed in 83.5% of patients, predominantly wide excision (37.0%). Incidence increased over the study period, with 40.3% of cases diagnosed between 2016 and 2022. Five-year and 10-year CSS rates were 95.9% and 93.7%, respectively. Stage-specific 5-year CSS was 97.6% for localized, 76.6% for regional, and 47.6% for distant disease (P < .001). On multivariate analysis, age (adjusted hazard ratio [aHR] = 1.042 per year, P = .003), disease stage (aHR = 4.368 per level, P < .001), and radiation therapy (aHR = 3.073, P = .010) were independently associated with CSS. Wide excision demonstrated improved survival compared to no surgery on univariate analysis (HR = 0.349, P = .026). Localized porocarcinoma treated surgically demonstrates excellent prognosis, with 5-year CSS exceeding 97%. Advanced disease confers significantly worse outcomes. Age and disease stage are independent prognostic factors. The increasing incidence underscores the need for continued surveillance and development of effective systemic therapies for advanced disease.