Impact of Radiation Therapy Doses on Gut GVHD

By Patrick Daly - Last Updated: December 22, 2022

In a recent study, researchers evaluated the impact of different radiation therapy (RT) doses to the intestine on the occurrence of acute graft-versus-host disease (aGVHD) in patients who underwent allogeneic hematopoietic stem cell transplantation (HSCT) with a novel conditioning regimen of total marrow and lymphoid irradiation (TMLI) plus adaptive immunotherapy.

In an article published in Frontiers in Oncology, the investigators reported there was “no clear evidence” connecting TMLI doses with incidence of aGVHD; however, they acknowledged their findings require further validation given the limitations of their analysis.

The study enrolled 50 patients with hematological malignancies who underwent TMLI conditioning between August 2015 and April 2021. Using patients’ treatment plans, researchers extrapolated RT doses to different intestinal areas and compared those with the dose to the rest of the intestine. They also evaluated dosimetrical parameters for the relationships with aGVHD.

Different RT Conditioning Doses Did Not Seem to Affect GVHD Rate

Among the cohort, 18 (36%) patients developed aGVHD—5 of grade II, 11 of grade III, and 2 of grade IV—with a median time to GVHD onset of 41 days (range, 23-69 days). Organs involved included skin in 11 patients, intestine in 16, and liver in 5.

Overall, the mean RT dose to the whole intestine was 7.1 Gy (range, 5.07-10.92), and no patient developed chronic GVHD. The authors reported no whole-intestine dosimetry parameters demonstrated an association with aGVHD risk. Likewise, no dosimetry parameters in intestine areas affected by aGVHD were associated with incidence.

In describing the limitations of their study, the authors suggested that “our clinical priority of administering low RT doses to the intestine so as to preserve intestinal function and prevent aGVHD may have been transformed into a drawback, as low doses were administered to the whole intestine and its segments, thus making a significant finding hard to emerge.”

Overall, the authors advanced their findings as preliminary evidence that different TMLI doses to the intestine do not appear to affect acute GVHD outcomes in patients who undergo allogeneic HSCT.

Read More: Ocular Surface Risk Factors for Ocular GVHD