Particular experimental therapy not more effective than standard treatment for anal canal cancer

Use of chemotherapy with the drug cisplatin before other treatments did not improve disease-free survival for patients with anal canal cancer compared to the standard treatment regimen, and resulted in a higher rate of colostomy procedures, according to a study in the April 23/30 issue of JAMA.

Chemoradiation is the preferred primary therapy for patients with anal canal cancer; however, the 5-year disease-free survival rate from concurrent fluorouracil/mitomycin (anti-cancer drugs) and radiation is only approximately 65 percent. It has been suggested that reducing the cancer in the primary tumor and in the lymph node(s) prior to administration of chemoradiation could potentially be effective for treating anal canal cancer. It was hypothesized for this study that disease-free survival might be improved by administering induction chemotherapy (use of chemotherapy as initial treatment before surgery or radiotherapy of a malignancy) with the anti-cancer drug cisplatin, to down-stage or downsize the cancer prior to concurrent chemoradiation. Pilot studies with this therapy had encouraging results.

Jaffer A. Ajani, M.D., of the University of Texas M. D. Anderson Cancer Center, Houston, and colleagues conducted a randomized controlled trial comparing treatment with fluorouracil plus mitomycin and radiotherapy vs. treatment with fluorouracil plus cisplatin and radiotherapy in 682 patients with anal canal cancer. A total of 644 patients were included in the analysis. The median (midpoint) follow-up for all patients was 2.51 years.

The 5-year disease-free survival rate was 60 percent in the mitomycin-based group and 54 percent in the cisplatin-based group. The 5-year overall survival rate was 75 percent in the mitomycin-based group and 70 percent in the cisplatin-based group, with more cancer-related deaths in the cisplatin-based group (54 patients) compared with the mitomycin-based group (28 patients).

The 5-year local-regional recurrence and distant metastasis rates were 25 percent and 15 percent, respectively, for mitomycin-based treatment and 33 percent and 19 percent, respectively, for cisplatin-based treatment. Severe hematologic (blood) toxicity was worse with mitomycin-based treatment.

Cisplatin-based treatment resulted in significantly higher cumulative rates of colostomy (19 percent vs. 10 percent; surgery to create an alternative exit from the colon created to divert waste through a hole in the colon and through the wall of the abdomen) and should generally be avoided in this patient population as primary therapy, the authors write.

“The question remains how to further improve disease-free and colostomy-free survival relative to the continued standard of concurrent chemoradiation with fluorouracil and mitomycin. … Options to explore include targeted agents (e.g., results with concurrent cetuximab plus radiation for head/neck cancer), dose escalation with intensity-modulated radiation plus concurrent chemotherapy, and surgical excision of residual cancer after concurrent chemoradiation at an earlier interval, when sphincter preservation may still be feasible in select patients.”