Safety
There were no significant differences in toxicity between the treatment arms.
Dr. Gronberg noted that esophagitis is considered the main dose-limiting toxicity with TRT, but there was no difference in incidence between the two arms (P = .916). Grade 3 esophagitis occurred in 18.4% of patients in the lower-dose arm and 19% of those in the higher-dose arm. There was no grade 4 esophagitis.
Rates of grade 3 and 4 neutropenic infections were higher in the lower-dose arm than in the higher-dose arm, but the difference was not statistically significant (P = .08).
There were also no significant differences in quality of life surveys that patients filled out periodically from baseline until week 52.
“Not so surprisingly,” Dr. Gronberg said, dysphagia was more common at the end of TRT. However, patients had recovered to baseline levels at week 22.
“There’s no difference in the maximum dysphagia reported between the treatment arms, but ... patients in the high-dose arm needed longer time to recover from dysphagia,” Dr. Gronberg said.
Scores for dyspnea, physical function, and global quality of life were similar between the treatment arms.
The similar toxicity between the arms “is quite puzzling,” Dr. Faivre-Finn said, given the 33% increase in radiation dose in the experimental arm. She said this “probably points out an imbalance in some of the factors” between the groups, including tumor volume and doses to organs at risk, which were not reported.
“There are some important missing data, in terms of interpretation of results,” she said.
Given the limitations, and the fact that the study population was relatively small, Dr. Faivre-Finn said “the results cannot be considered definitive and practice changing,” pending additional study.
“So my final conclusion is that twice-a-day radiotherapy at a dose of 45 Gy remains the standard of care, as recommended in the recently published ASTRO [American Society for Radiation Oncology] guidelines,” Dr. Faivre-Finn said.
The study was funded by the Norwegian Cancer Society, the Nordic Cancer Union, and the Norwegian University of Science and Technology. Dr. Gronberg disclosed relationships with Pfizer, Roche, Eli Lilly, and other companies. Dr. Faivre-Finn disclosed relationships with AstraZeneca, Merck, Pfizer, Elekta, and Boehringer Ingelheim.
SOURCE: Gronberg B et al. ESMO 2020, Abstract 1783O.