Women with cervical or endometrial cancers who underwent pelvic intensity-modulated radiation therapy reported fewer acute genitourinary and gastrointestinal toxicities than those who received standard radiation therapy, according to results of a randomized phase 3 trial presented at the ASTRO Annual Meeting.
Patients who underwent intensity-modulated radiation therapy (IMRT) also experienced better quality of life during treatment.
Ann H. Klopp
“We will need to follow these patients longer term to find out how these changes persist, or if they do,” Ann H. Klopp, MD, PhD, associate professor in the department of radiation oncology at The University of Texas MD Anderson Cancer Center, said during a press conference.
A considerable percentage of women diagnosed with cervical or endometrial cancer undergo radiation therapy after surgery. However, no consensus had been reached about which form of pelvic radiation most effectively eradicated tumors and reduced harm to surrounding healthy tissue.
Retrospective studies showed IMRT reduced acute and chronic gastrointestinal toxicity compared with standard four-field radiation therapy. The prospective RTOG 0418 trial also showed IMRT may be feasible in this setting because rates of acute toxicity were low, Klopp said.
IMRT can minimize the radiation dose delivered to normal tissue, including the small bowel in the center of the pelvis.
However, no randomized studies that compared approaches had been performed.
Klopp and colleagues conducted an international multicenter study designed to assess patient-reported acute toxicities in the genitourinary and gastrointestinal systems after standard four-field radiation therapy or IMRT, a form of external beam radiation therapy that delivers precise doses based on each patient’s tumor.
The analysis included 278 patients with endometrial or cervical cancer who required postoperative radiation.
Researchers stratified patients by dose (45 Gy or 50.4 Gy), chemotherapy receipt (none vs. five cycles of weekly cisplatin 40 mg/m2, administered at physician discretion) and disease site.
Klopp and colleagues then randomly assigned patients to IMRT or standard four-field radiation.
Change in acute gastrointestinal toxicity from baseline to 5 weeks — measured by the bowel domain of the Expanded Prostate Cancer Index Composite (EPIC) — served as the primary endpoint. The composite measured patient-reported frequency of rectal urgency, uncontrolled leakage of stool, loose or bloody stools, and painful bowel movements.
It also measured bowel bother, which accounted for how significant of a problem these specific issues and bowel habits in general had been for patients.
Negative change scores represented functional decline.
Secondary endpoints included adverse events, urinary toxicity as measured by EPIC, and quality of life as measured by the Functional Assessment of Cancer Therapy — General with cervix subscale (FACT-Cx).
At 5 weeks, patients assigned conventional radiation therapy reported a significantly larger mean decline in EPIC bowel summary score (-23.6 vs. -18.6; P = .048), and a significantly larger median change in bowel function subscale (-17.9 vs. -14.3; P = .03). Researchers reported no significant difference between treatment groups regarding the bowel bother subscale.
Patients assigned conventional radiotherapy reported a significantly larger mean decline in EPIC urinary summary score (-10.4 vs. -5.6; P = .03).
They also experienced more high-level adverse events related to diarrhea (P = .01 for frequency) and fecal incontinence (P = .01 for frequency; P = .04 for interference), both of which were determined with the NCI’s PRO-CTCAE measuring system.
A significantly higher percentage of women assigned standard radiation therapy reported taking at least four antidiarrheal medications daily (20.4% vs. 7.8%; P = .04).
An analysis of quality-of-life outcomes, measured by FACT-Cx, evaluated patients’ physical, social, emotional and functional well-being. The tool also measured additional treatment-related concerns, such as body appearance, interest in sex, vaginal symptoms, urinary function and appetite.
Results showed patients assigned standard radiation demonstrated greater declines in trial outcome index scores (-12.8 vs. -8.8), physical well-being (-6.1 vs. -4.2; P = .03) and additional treatment concerns (-4.9 vs. -2.7; P = .01).
“Many radiation oncologists also use IMRT for women undergoing pelvic radiation, but this research provides data that using IMRT — which is a more resource-intensive treatment — makes a real difference to patients receiving radiation therapy to the pelvic area,” Klopp said in a press release. “When performed by an experienced radiation oncology team, IMRT reduces the risk of short-term bowel and bladder side effects for patients with endometrial and cervical cancer.” – by Mark Leiser
Klopp AH, et al. Abstract 5. Presented at: ASTRO Annual Meeting; Sept. 25-28, 2016; Boston.
Disclosure: The researchers report no relevant financial disclosures.