Research presented yesterday at the 57th annual meeting of the American Society for Radiation Oncology (ASTRO) suggests image-guided intensity-modulated radiation therapy (IG-IMRT) causes fewer moderate-to-severe bowel side effects in cervical cancer patients who undergo post-surgical radiation therapy than conventional 3-D conformal radiation therapy (3-D CRT).

Post-operative pelvic radiation therapy is the standard treatment for many cervical cancer patients, but it can lead to long-term gastrointestinal side effects since it might affect surrounding organs and tissue. However, IG-IMRT reduces radiation exposure to surrounding tissue because it adjusts the radiation beams to the shape of the tumor.

The Advanced Centre for Treatment Research and Education in Cancer (ACTREC) in Tata Memorial Centre in Mumbai, India conducted a phase III randomized, clinical trial to investigate the effects the treatments have on cervical cancer patients. They brought together a group of 240 patients, 18 years old and over, who were undergoing combined chemotherapy and radiation therapy and had no pre-existing bowel disease or injury.
The researchers evaluated 117 of the patients who underwent an average 20-month follow-up, and split 56 patients into the 3-D CRT group and 61 patients into the IG-IMRT group. The 3-D CRT group received treatment on a linear accelerator and the IG-IMRT group received tomotherapy.

The researchers found that in the 3-D CRT group, 58.9 percent of the patients experienced moderate to severe diarrhea, vomiting, nausea, lower abdominal distension or pain, versus 54 percent in the IG-IMRT group. In addition, 17.6 percent of patients in the 3-D CRT group compared to 3.2 percent in the IG-IMRT group experienced severe diarrhea, lower abdominal pain, subacute intestinal obstruction that required medical or surgical intervention, bowel perforation, or death.

"These initial results of this interim analysis are encouraging and trend toward, possibly, a clinically important reduction in moderate-to-severe bowel side effects with the use of IG-IMRT. However, at interim analysis the results are statistically non-significant," Dr. Supriya Chopra, lead study author and associate professor of radiation oncology at ACTREC, said in a statement.

Even though this trial only assessed cervical cancer patients, many patients with other forms of cancer undergo postoperative pelvic radiation around the world. Chopra believes that the results of this trial could influence the choice of future radiation delivery techniques for other pelvic malignancies.

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