Intensity-modulated radiotherapy improves survival and reduces treatment time in squamous cell carcinoma of the anus: A National Cancer Data Base study.

BACKGROUND: Chemoradiation with 5-fluorouracil and mitomycin remains the standard of care for squamous cell carcinoma (SCC) of the anal canal. A prolonged treatment time is associated with inferior disease-specific outcomes. Radiation Therapy Oncology Group trial 0529 demonstrated decreased toxicity and fewer treatment breaks with intensity-modulated radiotherapy (IMRT), but this has not been assessed in a randomized trial. Using data from the National Cancer Data Base (NCDB), this study evaluated the impact of IMRT on treatment time and survival in anal SCC.

METHODS: The NCDB was used to identify patients with anal cancer from 2004 to 2013. The included patients were those with stage I to III squamous cell cancer of the anal canal who had received definitive chemoradiation by IMRT or 3-dimensional conformal radiation therapy (3DCRT). Statistical analyses were performed with logistic regression, Kaplan-Meier analysis, Cox proportional hazards analysis, and propensity score-matched analysis.

RESULTS: Of 6814 patients, 57.4% were treated with 3DCRT, whereas 42.6% received IMRT. Patients receiving IMRT had a reduced risk of a long treatment time in a multivariate analysis (P < .001). The 5-year overall survival (OS) rates with IMRT and 3DCRT were 80.8% and 78.9%, respectively (P = .0036). According to a propensity analysis, patients receiving IMRT had improved OS (P = .039) and a reduced risk of a long treatment time (P < .0001) in a multivariate analysis.

CONCLUSIONS: IMRT use was associated with significantly reduced overall treatment time and improved survival in comparison with 3DCRT. It is important to note that NCDB data are not as robust as randomized data. However, these results further support the use of IMRT as part of sphincter-preserving therapy for the anal canal.