What factors are associated with the poor prognosis of anal adenocarcinoma compared with low-lying rectal adenocarcinoma based on a population analysis: A propensity score matching study

Abstract

Purpose Anal adenocarcinoma (AA) represents a rare condition, and little is known about the predictive factors of the outcomes or the optimal TNM staging system for curable AA. Using population-based data, we preliminarily sought to determine the prognostic factors and evaluate the existing T and N staging criteria of AA. Methods We analyzed the Surveillance, Epidemiology, and End Results 18 database to identify patients 20–80 years old who were diagnosed with AA or rectal adenocarcinoma (RA) and underwent abdominal perineal resection between 2004 and 2012. The difference between Kaplan-Meier survival curves was estimated by a log-rank test. A Cox proportional hazard regression model was used to adjust the effects of other covariates on survival in the propensity score-matched cohort, including age, gender, race, marital status, histology, grade of differentiation, tumor size, number of positive lymph nodes, radiotherapy, and chemotherapy. Results Compared to patients with RA, patients with AA had a worse CSS after controlling for other covariates (hazard ratio [HR], 1.96; 95% confidence interval [CI], 1.25–3.07; P<0.01). For AA, the increasing tumor size (2–5 cm: HR, 0.62; 95% CI, 0.29–1.32; P>0.05; >5 cm: HR, 1.01; 95% CI, 0.49–2.07; P>0.05) had no significant influence on survival. The number of positive lymph nodes (1–3: HR, 2.93; 95% CI, 1.55–5.53; P<0.01; ≥4: HR, 4.24; 95% CI, 2.08–8.62; P<0.01) significantly influenced survival. Conclusions AA confers a worse prognosis than RA does. The T staging criteria of anal carcinoma, dominated by tumor size, seem to be invalid for AA, while the number of positive lymph nodes is a prognostic factor.

Management and Outcomes in Anal Canal Adenocarcinomas—A Systematic Review

“…Low survival outcomes are also observed in the Franklin et al and Lewis et al studies [ 10 , 15 ]. More recent studies are also in agreement, such as the one by Wang et al in 2019 that has shown adenocarcinoma of the anus having a worse prognosis than rectal adenocarcinoma and, in addition, stating that the T staging criteria for anal carcinoma may not be valid for staging anal adenocarcinoma [ 14 ].…”

“…The studies by Bertelson et al [ 9 ], Franklin et al [ 10 ], Lewis et al [ 15 ], Wang et al [ 14 ], McKenna et al [ 12 ], Leong et al [ 13 ] and Gogna et al [ 20 ] did not provide values for the 5-year overall survival rates or any OS rate values for each treatment group. In the Franklin et al study of 307 patients, the 1-, 3-, 5- and 10-year survival rates were 76.8%, 46.2%, 30.2% and 16.2%, respectively.…”