A territory wide follow-up of primary and secondary extramammary Paget disease of two decades - effects of local disease on survival.

Introduction Extramammary Paget disease (EMPD) is an uncommon malignant cutaneous neoplasm that are divided into primary and secondary forms. In this multicenter study, histologically proven cases of primary and secondary EMPD were reviewed for clinical outcomes with subgroup analysis for secondary EMPD. Methodology Cases of EMPD were identified from pathology report of the involved institutions over a period of over two decades. Cases of secondary EMPD were identified review of case notes, radiology, and pathology reports. Clinicopathological and outcome data were retrieved for statistical analysis. Results A total of 109 cases were retrieved, including 19 cases of secondary EMPD, most commonly associated with colorectal (n=6), anal (n=5) and prostatic carcinomas (n=3). A difference was observed between older age and secondary (versus primary) EMPD (p=0.016), but no differences were seen in other clinico-demographical parameters. Male sex (p=0.018), age over 60 years old (p=0.004) and involvement of margins (resectable) (p=0.018) were associated with shorter OS. For DSS, involvement of margins (p=0.009) was an adverse predictor. Secondary EMPD had a shorter DSS than primary EMPD (p=0.005). Multivariable analysis confirmed all above associations (p<0.05). In subgroup analysis for secondary EMPD, margin involvement remained associated with shorter OS (p = 0.007) and DSS (p = 0.003). Conclusions Secondary EMPD is associated with poorer outcomes. Margin involvement is strong and independent indicator of shorter OS and DSS, including secondary EMPD. Resectability is a strong predictor of favorable outcome and excision with clear margins should be attempted when surgically feasible.