A Population-Based and Propensity Score-Matched Investigation of the Occurrence, Management, and Prognosis of Anal Mucinous Adenocarcinoma Patients

Abstract

<b><i>Introduction:</i></b> Anal mucinous adenocarcinoma (AMAC) is an extremely rare form of anal cancer. Our objective was to examine the incidence, management, and prognostic factors of AMAC. <b><i>Methods:</i></b> We analyzed age-adjusted incidence (AAI) rates over time and compared the prognosis of AMAC with anal squamous cell carcinoma (ASCC) and adenocarcinoma (AAC) using propensity score matching and Kaplan-Meier analysis. Patients were classified based on summary stage and treatments to determine cancer-specific survival. <b><i>Results:</i></b> AAI of AMAC fluctuated within a narrow range (0.082–0.237 per million person-years) from 2000 to 2018. AMAC had a slight non-significant trend of worse prognosis than ASCC (<i>p</i> = 0.348) and a better prognosis than AAC (<i>p</i> &lt; 0.01). Females made up a larger proportion of patients diagnosed with the distant disease (<i>p</i> &lt; 0.05) and unmarried (<i>p</i> &lt; 0.05) and somewhat less probably to need surgical removal (<i>p</i> &lt; 0.01) and radiotherapy (<i>p</i> &lt; 0.01). Elderly patients have lower rates of survival (<i>p</i> &lt; 0.05). Localized stage was associated with better prognosis (<i>p</i> &lt; 0.05). Surgery was associated with a tendency toward better survival (<i>p</i> = 0.095). <b><i>Conclusions:</i></b> AMAC exhibits a low incidence yet favorable prognosis compared to typical AAC and slightly worse compared to ASCC. Elderly age is associated with poorer prognosis, while localized stage indicates better prognosis. Surgery demonstrates a trend toward improved survival.