Findings from the largest trial ever conducted for anal cancer, presented at the American Society of Clinical Oncology, have shown that the current standard of care, using a novel, continuous radiation therapy delivery program combined with 5-fluorouracil (5-FU) and mitomycin-C chemotherapy, results in the best outcomes so far reported for patients with anal cancer, and that cisplatin chemotherapy is not superior to mitomycin-C. The study also showed no evidence of a benefit of adding maintenance chemotherapy to the standard of care.

Anal cancer is rare, with about 5,000 patients diagnosed in the United States each year. Unlike colorectal cancer, the majority of patients with anal cancer do not need surgery, largely because the tumours are the squamous cell type, which are very responsive to chemotherapy and radiation. Cisplatin is commonly used for other squamous cell cancers, but it is less convenient to deliver and is known to have different toxicities from mitomycin-C, such as neurological and renal side effects and hearing loss.

The current study, called ACT II, conducted by the National Cancer Research Institute in the United Kingdom, and funded by Cancer Research UK, randomized 940 patients to receive radiation therapy given at the same time as 5- FU with either mitomycin-C or cisplatin. Patients were also randomised to receive follow-up maintenance therapy with cisplatin and 5-FU after chemoradiation or no maintenance therapy.

After a median follow-up of three years, the investigators found no significant difference in outcome in the two randomised comparisons:

- The complete response rate at 6 months (the number of patients who had all signs of their cancer disappear) was 94 percent in the mitomycin-C group compared with 95 percent in the cisplatin group.
- Recurrence-free survival at 3 years (the number of patients whose tumours did not return) was 75 per cent both in patients who got maintenance therapy and in those who did not.
- Overall survival at 3 years was 85 per cent in patients who received maintenance therapy and 84 per cent in those who did not.

"These findings are good news in spite of the lack of evidence for an improvement in giving either cisplatin or maintenance therapy, since the standard chemoradiation schedule given in this trial was highly effective," said Dr. Roger James, a radiation oncologist from Maidstone Hospital, Kent, and the study’s lead author. "Although this trial did not show an improvement from adding maintenance therapy, some form of additional treatment will be the subject of future studies, to determine whether some subset of patients might benefit from it."