SAN FRANCISCO-Although generally considered a contraindication for definitive prostate cancer treatment, radiation appears to be safe for men who have been diagnosed with co-morbid inflammatory bowel disease, researchers suggested here at the 2016 Genitourinary Cancers Symposium (Abstract 15).
In a small series of patients, doctors found no evidence of serious adverse events-no Grade 3 or greater gastrointestinal adverse findings-in their retrospective study, said Matthew Gestaut, MD, a radiation oncology resident at Scott & White Health/Texas A&M University, Temple, Texas.
Implications
"Until now, no published data are available exploring radiation therapy for patients with prostate cancer and inflammatory bowel disease," Gestaut told OT at his poster presentation. "In our retrospective review, no post-radiation complications occurred. Our findings suggest that inflammatory bowel disease patients experience minimal toxicity in the era of intensity modulated radiation therapy."
He noted, however, that convincing doctors might take further study. He and his colleagues were surprised to find that when they searched their own database for patients with prostate cancer and co-morbid inflammatory bowel disease over a 15-year period (1995 to 2010), they found just 166 cases. The average length of follow-up in the patient population was 12 years.
"When we queried the tumor registry and found there were 166 patients with both inflammatory bowel disease and prostate cancer, we thought we had a large patient population. But then going through those patients' charts, about 80 percent of them actually went to surgery," Gestaut said.
"We only had 18 patients who were treated with radiation," he continued. "The primary reason they went to surgery was because they had inflammatory bowel disease.
"Historically and presently, doctors worry that treatment with radiation could make inflammatory bowel disease worse in prostate cancer," he said. "But there is no evidence for this concern. It is a rarely encountered clinical situation, but it is encountered."
He continued, "In patients who underwent surgery in our study, the primary reason cited for offering surgery instead of radiation was the concomitant diagnosis of inflammatory bowel disease and fear of increased complication rates with radiation."
Study Specifics
With a median follow-up of 9.5 years, the research team observed that 16 of the 18 patients offered radiation therapy were diagnosed with ulcerative colitis; the other two men were diagnosed with Crohn's disease. Four of the patients were in remission from their inflammatory bowel disease; others were on various medications. Twelve of the men were treated with external beam radiation therapy-six with intensity modulated radiation therapy and six with 3-dimensional conformal radiation therapy-and the other six men underwent low-dose brachytherapy.
At baseline none of the patients were observed to have proctitis. After treatment, 12 of the men had Grade 0 proctitis; three had Grade 1 proctitis; and three had Grade 2 proctitis. All of the men with Grade 2 proctitis were treated with 3-dimensional conformal radiation therapy, Gestaut said. All of the cases of proctitis resolved within five years with 5-aminosalicylic acid therapy.
"Grade 1 adverse events means there is no need to change medication, no need to change dosage," he explained. "This inflammation of the rectum requires some treatment if it is Grade 2. Grade 1 proctitis involves some discomfort but there is no need to treat it medically. Grade 2 proctitis can be treated with suppositories or other therapies. Grade 3 proctitis might require surgery but we didn't have that in our patients. No Grade 3 toxicities were experienced."
Gestaut said that 14 of the 18 patients reported Grade 0 diarrhea; four others reported Grade 1 diarrhea. No Grade 2 or Grade 3 cases of diarrhea were reported, and no post-radiation stricture or ostomy placements occurred.
"This retrospective review offers valuable insight into appropriate counseling for a rare patient subset," Gestaut said. "All those patients who did have Grade 2 proctitis were treated with an older form of radiation therapy.
"We can tell patients now that those treated with intensity modulated radiation therapy have not had that level of toxicity," he said.
Interpreting Results
"Theoretically the possibility of proctitis is always there, and we just had 18 patients so our results may be limited in their interpretation," Gestaut said. "However, I would offer radiation therapy to these patients. I would tell them that surgery is an option, brachytherapy would be an option and external beam radiation therapy could be an option, too. I think it is an injustice to take the radiation option away from these patients."
Safe Option?
In commenting on the study, Oliver Sartor, MD, Medical Director at the Tulane Cancer Center, Director of the Prostate Cancer Program and Laborde Professor of Cancer Research in New Orleans, told OT: "Generally, people shy away from radiation out of caution, but this study seems to indicate that these patients did pretty well. The six cases of Grade 1 or Grade 2 proctitis isn't bad at all.
"This preliminary data would suggest that radiation in the inflammatory bowel disease population may be a safe option," Sartor said. "I have not seen data on this before; it is interesting. I would be willing to talk to patients about this option if they were opposed to surgery.
"This might also apply in the salvage setting as well, if these patients have recurrences and need radiation to the pelvis. This is a small study but it does have clinical implications and could change the way patients are counseled," Sartor said.
Be Cautious
Yet, Sumanta Pal, MD, Assistant Professor of Medical Oncology at City of Hope, Duarte, California, threw up the caution flag. "Because this is so small a study with just 18 patients, the experience is not there yet to define whether radiation is safe in this population. I would still be worried about the inherent predisposition to the gastrointestinal toxicity in this population.
"This study does provide some preliminary evidence," he acknowledged, "so in someone who is absolutely not a surgical candidate but intends on receiving definitive therapy, you could potentially explore the option. However, I would not use it routinely for patients who otherwise could be considered for surgical intervention."
The symposium is co-sponsored by the American Society of Clinical Oncology, American Society for Radiation Oncology, and Society of Urologic Oncology.