New research into the treatment of gastrointestinal cancers ? and novel ways to predict recurrence and response to chemotherapy ? were presented during the eighth annual Gastrointestinal Cancers Symposium, held January 20-22, 2011, at The Moscone West Building in San Francisco.

One study, a Phase II Radiation Therapy Oncology Group (RTOG) trial, showed that combining chemotherapy with intensity-modulated radiation therapy (IMRT) is just as effective after two years in treating anal cancer as chemotherapy and conventionally delivered radiation therapy, but with fewer significant side effects.

?Radiation therapy with concurrent 5-fluorouracil and mitomycin-C chemotherapy serves as the standard of care for patients with non-metastatic squamous cell cancer of the anal canal in the United States,? explained lead researcher Lisa Kachnic, MD, chair of radiation oncology at Boston University and principal investigator of RTOG trial 0529. ?This treatment results in long-term disease-free survival, but is associated with significant acute toxicity due in part to the large radiation fields used. The use of IMRT may address this problem.?

In contrast to two or three-dimensional conventional radiation fields, which indiscriminately treat normal organs, IMRT is a novel technology that conforms or ?paints? the radiation dose to the tumor and lymph node regions, while sparing healthy surrounding tissues. Improvements in treatment-related toxicity have already been described in patients with breast, head and neck and prostate cancers treated with IMRT, as compared to conventionally delivered radiation therapy.

In the current study, Dr. Kachnic and the RTOG analyzed the outcome of 52 stage II and stage III patients with anal cancer treated with IMRT and 5-fluorouracil/mitomycin-C chemotherapy.

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After a median follow-up of 26.7 months, the two-year disease-free survival was 77%, and overall survival was 86 percent. These results were very similar to the 325-patient, 5-fluorouracil/mitomycin-C arm of the RTOG 9811 trial, which used conventionally delivered radiation: 75% disease-free survival and 91% overall survival (OS) at two years. However, the use of IMRT in RTOG 0519 was associated with less skin and gastrointestinal acute toxicity.

?Based on RTOG 0529, IMRT with 5-fluorouracil and mitomycin-C is associated with significant sparing of grade three and higher dermatologic and gastrointestinal acute toxicity as compared to the 5-fluorouracil/mitomycin-C and conventionally delivered radiation arm of RTOG 9811, without compromising two year outcomes,? said Dr. Kachnic. ?IMRT will now serve as the standard radiation technique in future RTOG anal cancer trials assessing novel agents in combination with radiation.?

For more information:
Kachnic LA, Winter KA, Myerson RJ, Goodyear MDE, Willins J, Esthappan J, Two-year outcomes of RTOG 0529: A phase II evaluation of dose-painted IMRT in combination with 5-fluorouracil and mitomycin-C for the reduction of acute morbidity in carcinoma of the anal canal. Abstract #368

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