Rational treatment options for T1/2N0M0 squamous cell carcinoma of the anal canal: a population-based study combined with external validation

Abstract

Background: Treatment options for T1/2N0M0 anal squamous cell carcinoma include chemotherapy, radiotherapy, chemoradiotherapy, and local excision, although the optimal treatment method has not been determined.

Methods: The National Cancer Institute Surveillance, Epidemiology and Results database was used to search and screen 1465 patients with cT1/2N0M0 anal squamous cell carcinoma who were clinically diagnosed between 2004 and 2016. Survival analysis was performed using the Kaplan-Meier method and log-rank test. Cox proportional hazards regression analysis was performed to screen independent prognostic factors and build a nomogram survival prediction model. According to the risk score, patients were divided into low, medium, and high risk groups using X-tile software.

Results: Age, sex, grade and cT stage were identified as independent prognostic factors for cT1/2N0M0 anal squamous cell carcinoma and were included in the nomogram to construct a prediction model. The C-index of the model was 0.770 [95% confidence interval (CI), 0.693-0.856], which was higher than the C-index of T stage 0.565 (95% CI, 0.550-0.612). Low-risk patients benefited from local resection, moderate-risk patients benefited from radiotherapy, and high-risk patients benefited from radiotherapy or chemoradiotherapy. This was confirmed using external validation data from the center.

Conclusion: The nomogram developed in this study effectively and comprehensively evaluated the prognosis of patients with cT1/2N0M0 squamous cell carcinoma of the anal canal. Local excision is recommended for low risk patients, radiotherapy for moderate-risk patients, and radiotherapy or chemoradiotherapy for high-risk patients.

Keywords: cT1/2N0M0 squamous cell carcinoma of the anal canal; nomogram; prognosis; rational treatment.

Figure 1.

Flowchart of the selection process of included patients.

Figure 2.

The Kaplan-Meier curves of OS for patients in our study. (A) OS for patients with LE, (B) OS for patients with CT, (C) OS for patients with RT, (D) OS for patients with CRT, (E) OS in different subgroups of all patients.

Figure 3.

Oncologic nomogram for T1/2N0M0 SCCA.

Figure 4.

Calibration curves and decision curve for OS prediction: (A) 3-year OS calibration curve in our cohort; (B) 5-year OS calibration curve in our cohort; (C) Nomogram were compared to the T stage in terms of 3-year OS in our decision curve analysis; (D) Nomogram were compared to the T stage in terms of 5-year OS in our decision curve analysis.

Figure 5.

X-tile analysis for risk stratification: (A) The optimal cutoff value, (B) numbers of patients in low-, moderate-, and high-risk subgroups.

Figure 6.

The Kaplan-Meier curves of OS for patients. (A) OS in different risk subgroups of non-LE group, (B) OS in different risk subgroups of LE group, (C) OS for patients with or without LE in low-risk group, (D) OS for patients with or without LE in moderate-risk group, (E) OS for patients with or without LE in high-risk group, (F) OS in different risk subgroups of non-CT group, (G) OS in different risk subgroups of CT group, (H) OS for patients with or without CT in low-risk group, (I) OS for patients with or without CT in moderate-risk group, (J) OS for patients with or without CT in high risk group.