Patients with cervical and endometrial cancer have fewer gastrointestinal and genitourinary side effects and experience better quality of life when treated with intensity-modulated radiation therapy (IMRT) than with conventional radiation therapy (RT), according to research presented today at the 58th Annual Meeting of the American Society for Radiation Oncology (ASTRO).

Women receiving IMRT reported significantly fewer bowel and bladder problems than those receiving conventional radiation treatment.

Many women diagnosed with cervical or endometrial cancer receive RT following surgery to remove their tumours, but questions remain as to which form of pelvic RT delivery can most effectively eliminate the tumour while minimising the impact of radiation on surrounding healthy tissue.

This multi-center, international study assessed this impact by evaluating patient-reported acute toxicities in the gastrointestinal (GI) and genitourinary (GU) systems following IMRT, an advanced form of external beam RT that delivers precise radiation doses highly tailored to patients’ individual tumours, versus standard four-field RT.

“The way that radiation therapy is performed has a major impact on the risk of side effects from treatment,” said Ann H. Klopp, MD, PhD, lead author of the study and an associate professor in the department of radiation oncology at the University of Texas MD Anderson Cancer Center in Houston. “We know that IMRT reduces the amount of normal tissue irradiated, so we suspected that it would have fewer side effects. This was one of the first studies, however, to rigorously ask this question using patient questionnaires to ensure that the lower doses resulted in meaningful differences in patients’ experiences during treatment.”

A total of 278 patients with cervical or endometrial cancer who received pelvic RT post-operatively at cancer centers in the U.S., Canada, Japan and Korea were evaluated to determine if pelvic IMRT for cervical and endometrial cancer resulted in fewer patient-reported GI and GU side effects and improved patients’ QOL.

Patients were stratified based upon RT dose (45 Gy or 50.4 Gy), use of chemotherapy (no chemotherapy or five cycles of weekly cisplatin at 40 mg/m2), and disease site.

The patients were then randomly assigned to receive standard RT or IMRT.

Acute GI and GU toxicities and QOL were measured via multiple patient questionnaires.

Instruments included the Expanded Prostate Cancer Index Composite (EPIC) to measure bowel and urinary toxicities, the Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events (PRO-CTCAE) to assess GI- and GU-related adverse events (e.g., diarrhoea), and the Functional Assessment of Cancer Therapy – General with cervix subscale (FACT-Cx) to track health- related QOL.

Researchers compared changes in average scores on these instruments from baseline to five weeks following RT start using two-way t-tests.

Patients in the IMRT arm experienced significantly fewer bowel-related toxicities than patients who received standard RT did, as indicated by smaller average declines in their EPIC bowel domain scores (- 18.6 vs. -23.6, p = 0.048).

Analysis of sub-scales within the EPIC determined that IMRT patients experienced less severe declines in bowel function but not bowel bother.

IMRT patients also experienced fewer high-level adverse events following treatment, including less diarrhoea (frequency: 33.7 vs. 51.9 percent, p = 0.01) and fecal incontinence (frequency: 1.1 vs. 9.3, p = 0.01).

Moreover, roughly one in five women in the standard RT group (20.4 percent) reported taking four or more anti-diarrhoeal medications daily, compared to 7.8 percent of women in the IMRT group (p = 0.04).

Urinary side effects at five weeks from treatment start were less prevalent among patients who received IMRT, as indicated by significantly smaller declines in average EPIC urinary domain scores for the IMRT arm (-5.6 vs. -10.4, p = 0.03).

Furthermore, IMRT regime negatively impacted patients’ QOL less substantially than the conventional RT regime did. FACT-Cx trial outcome index scores demonstrated less decline in health-related QOL following IMRT compared to standard RT (-8.8 vs. -12.8, p = 0.06).

Patients treated with IMRT had less change in physical well-being (-4.2 vs. -6.1, p = 0.03) and addition concerns (-2.7 vs. -4.9, p = 0.01).

“Many radiation oncologists already 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,” said Dr. Klopp. “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.”

Source: 58th Annual Meeting of the American Society for Radiation Oncology (ASTRO).