ABSTRACT
Objective:To analyze the influence of clinicopathological features on the prognosis of anorectal malignant melanoma (AMM), and to establish a more accurate prognosis prediction model.Methods:From January 1, 2006 to December 31, 2018, at Fudan University Shanghai Cancer Center, the data of 89 patients diagnosed with AMM and underwent operation were retrospectively analyzed. The Cox proportional hazard regression model was used to analyze factors affecting the prognosis. Backward elimination was used to select variables, Nomogram prognosis prediction model was established and verified internally, and the consistency index was calculated.Results:Among 89 AMM patients, 65 (73.0%) were female, 78(87.6%) were <70 years old, and the most common tumor location was the rectum (48.3%, n=43), followed by the anal canal (31.5%, n=28) and the anorectal canal (20.2%, n=18). Thirty-eight (42.7%) patients directly received abdominal-perineal resection (APR), 37 patients (41.6%) received interferon-based immunotherapy, and 11 patients (12.4%) received both systemic chemotherapy and immunotherapy. The 3-year disease-specific survival (DSS) rate was 41.6%(37/89), and the 5-year DSS rate was 31.5%(28/89). The results of multivariate Cox analysis showed that age ≥70 years old and T2 stage were risk factors of the prognosis of AMM patients (hazard ratio ( HR)=11.29, 4.83; 95% confidence interval ( CI) 2.89 to 44.13, 1.66 to 14.11; both P<0.01), while neurovascular invasion, immunotherapy treatment, systemic chemotherapy combined with immunotherapy, APR after extensive local resection, directly APR and APR combined with inguinal lymphadenectomy were protective factors of the prognosis ( HR=0.09, 0.23, 0.10, 0.13, 0.26, 0.02; 95% CI 0.02 to 0.34, 0.10 to 0.57, 0.02 to 0.49, 0.03 to 0.52, 0.08 to 0.90, 0.00 to 0.27; all P<0.05). The Nomogram model was further established with age, gender, tumor location, T stage, distant metastasis, medication chemotherapy and surgical treatment. The results of the Nomogram model internal verification indicated that the accuracy of the model in predicting 1-year, 3-year and 5-year DSS was good, and the consistency index was 0.749, which was significantly higher than the consistency index of traditional TNM stage (0.607). Conclusions:Most AMM patients are <70 years old, and the majority of them are female. The common location of AMM is rectum, and many patients receive immunotherapy. Age ≥70 years old and T2 stage are risk factors affecting the prognosis of AMM patients. Neurovascalar invasion, immunotherapy based comprehensive treatment, APR after extensive local resection, directly APR and APR combined with inguinal lymphadenectomy are protective factors of the prognosis. Nomogram prognosis prediction model established based on the clinicopathological features and treatment of AMM patients has higher accuracy and clinical reference value than the traditional TNM stage system.