"Our primary end point was not met," said Dr. Kachnic, who reported having no conflicts of interest related to the trial. That is, the rate of grade 2 or higher acute gastrointestinal and genitourinary toxicities combined was essentially the same with IMRT and conventional radiation, at about 77% in each group.
The IMRT group did have significantly lower rates of grade 3 or higher acute gastrointestinal and genitourinary toxicities combined (P = .005), gastrointestinal toxicity alone (P = .008), and skin toxicity (P less than .0001), as well as a lower rate of grade 2 or higher acute hematologic toxicity (P = .03).
The IMRT and conventional radiation therapy patients had similar 2-year rates of efficacy outcomes, with overlapping 95% confidence intervals for locoregional failure (19% and 19%), colostomy failure (8% and 11%), colostomy-free survival (84% and 83%), disease-free survival (77% and 75%), and overall survival (86% and 91%).
"After short-term follow-up, IMRT appears to be as effective as conventional radiation in the treatment of anal cancer but with decreased side effects," commented Dr. Jennifer C. Obel, moderator of the presscast and a medical oncologist with the NorthShore University HealthSystem in Evanston, Ill. "By limiting treatment of nearby tissues, a patient’s quality of life is improved during treatment."
"While larger studies will need to be performed and longer follow-up is required, IMRT may emerge as a key treatment modality for anal cancers," noted Dr. Obel, who did not report any conflicts of interest.