Extended-field intensity modulated radiation therapy (EF-IMRT) can be safely used without risking duodenal toxicity in women with cervical or endometrial cancer in need of treatment to the para-aortic (PA) lymph nodes, researchers reported.
Usually, radiation therapy is applied to target the tumor and the lymph nodes, which play a key role in metastasis. Lymph nodes in cancerous patients are monitored by a technique called PET/CT, but it has a relatively high false-negative ratio (20–25 percent) when scanning PA regions. Radiation therapy applied only to the pelvis may not be sufficient, and EF-IMRT is recommended to treat patients’ PA regions as well. Because cervical and endometrial tumors can spread through lymph nodes, and the disease can develop in PA locations, the application of IMRT to para-aortic lymph nodes can also be preventative.
The research included 76 people with cervical or endometrial cancer. EF-IMRT treatment was applied to PA lymph nodes to treat tumors or to prevent disease development there. The patients’ average age was 54 and a total of 64 women had primary cervical cancer, and 12 had endometrial cancer. Forty-one patients were treated with EF-IMRT as a consequence of advanced tumors in the PA location, and 35 others as preventative therapy. The median follow-up time interval was 18.5 months.
Investigators found that the volume of the duodenum (a part of the small intestine) was a predictor of duodenal toxicity. No one in the study received more than V55 above 15 cm3, an established criterion for a higher risk of duodenal toxicity.
To measure adverse events, the NCI’s Common Terminology Criteria for Adverse Events (CTCAE) scale was applied: three of the 76 women (3.9 percent) had Grade 3 acute gastrointestinal (GI) toxicity, classified as “requiring hospitalization or elective operative intervention.” Three had Grade 2 GI toxicity, classified as a “likely duodenal obstruction creating symptomatic, altered GI function.”
“Our study confirms that when the duodenal dose was kept within the prescribed limits, V55 below 15cm3, patients who received EF-IMRT had very low rates of side effects and excellent regional control,” Sushil Beriwal, MD, the lead author and an associate professor of Radiation Oncology at the University of Pittsburgh Cancer Institute, said in a news release. “This is one of the largest studies to examine duodenal toxicity rate for EF-IMRT treatment of gynecologic malignancies. These findings are especially important for patients who have positive metastatic disease in the para-aortic lymph nodes; they are typically the patients with advanced cervical and endometrial cancer, many of whom will likely receive concurrent chemotherapy, which can increase the risk of side effects and toxicity. EF-IMRT is an excellent option for durable control of their disease.”
Dr. Beriwal added, “We hope to see larger, randomized trials to further define and refine EF-IMRT for these patients.”