For older patients with stage I squamous cell carcinoma of the anus, radiation alone is associated with outcomes that do not differ significantly from those of chemoradiation, according to research published in the July issue of Diseases of the Colon & Rectum.

Although the benefit of chemoradiation over radiation therapy alone has been shown in randomized trials for stage II to III squamous cell of the anus, this benefit is not clear for patients with stage I cancer.

Nevertheless, most societal recommendations endorse chemoradiation for patients with stage I squamous cell carcinoma of the anus despite the lack of proven benefit and a potential increase in toxicity.

The purpose of this study was to determine whether outcomes are improved with the addition of chemotherapy versus radiation alone for stage I squamous cell carcinoma of the anus.

Medicare-eligible patients (age >65 y or with an eligible disability) with stage I squamous cell carcinoma of the anus treated with either definitive radiation alone or chemoradiation were included. 

Radiation or chemoradiation

Radiation or chemoradiation was the intervention. Overall survival, disease-free survival, cause-specific survival, colostomy-free survival, and acute or late toxicities were measured.

Michael Buckstein, M.D., from the Icahn School of Medicine at Mount Sinai in New York City, and colleagues conducted a cohort analysis to examine whether outcomes are improved with the addition of chemotherapy to radiation alone for stage I squamous cell carcinoma of the anus. Data were included for 200 patients who received chemoradiation and 99 treated with lone radiotherapy (median age, 72 years).

The researchers found that, compared to patients treated with lone radiotherapy, patients receiving chemoradiation had improved unadjusted overall survival; however, after propensity-score method adjustment, there was no significant between-group difference in overall survival (hazard ratio, 0.7; 95% confidence interval, 0.4 to 1), cause-specific survival (hazard ratio, 0.7; 95% confidence interval, 0.3 to 1.6).

There was no significant between-group difference colostomy-free survival (hazard ratio, 1.1; 95% confidence interval, 0.5 to 2.5), or disease-free survival (hazard ratio, 0.9; 95% confidence interval, 0.6 to 1.4). The risk of select early and late toxicities was increased in association with chemoradiation.

"Lone radiation may be associated with adequate oncologic outcomes when used to treat older and sicker patients with stage I anal cancer," the authors noted. Several authors disclosed financial ties to the pharmaceutical industry.