Long-Course RT Better at Organ-Sparing in Rectal Cancer

Long-Course RT Better at Organ-Sparing in Rectal Cancer

Long-course radiation therapy for rectal cancer is more likely to spare organs than short-course therapy, including when chemotherapy is provided first as part of a total neoadjuvant therapy (TNT) strategy, shows new research presented at the ASCO Gastrointestinal Cancers Symposium 2023.

“When we looked at the 2-year organ preservation rates, they were numerically higher in the long-course group versus the short-course group,” said study author J. Joshua Smith, MD, PhD, FACS, a colorectal surgeon with Memorial Sloan Kettering Cancer Center, New York. “Our study will be the first, to our knowledge, that examines a significant proportion of patients treated with the induction total neoadjuvant therapy approach – chemo first.”

An ideal outcome in rectal cancer is no need for surgery, Dr. Smith said. “If you can avoid surgery altogether and preserve the organ [the rectum], that’s a big win for the patient as they are usually able to avoid having a permanent or temporary ostomy.”

Long-course and short-course radiation have similar outcomes in terms of patients going on to need surgery, but it’s not clear which is superior in terms of organ sparing, toxicity, and side effects, said Paul Romesser, MD, a radiation oncologist with Memorial Sloan Kettering Cancer Center, New York, who served as first author of the study.

During the early months of the COVID-19 pandemic, the cancer center embraced short-course radiation in rectal cancer, Dr. Romesser said. “Once we emerged from the cloud of COVID, we said: ‘Well, what do we do now? Where do we go? Do we go back to what we did before? Or, do we go stick with the same? And what does that mean for organ preservation?’ ”

The researchers retrospectively identified 563 consecutive patients treated with TNT from 2018 to 2021. They focused on 332 who didn’t have metastatic disease, synchronous/metachronous malignancies, or nonadenocarcinoma histology (long course = 256, short course = 76). The groups had similar high-risk features, and about 82% were clinical stage III).

Patients most commonly received induction chemotherapy followed by consolidative radiation (78% long course, 70% short course).

The 2-year survival rates were similar, but organ preservation was higher in the long-course group versus the short-course group (40%; 95% confidence interval, 35%-47% vs. 29%; 95% CI, 20%-42%). And the 2-year local regrowth rate was also better in the long-course group versus the short-course group (20%; 95% CI, 12%-27% vs. 36%; 95% CI, 16%-52%).

Why might long-course therapy be better? “It’s probably just coming down to the biologically equivalent dose,” which is likely lower in short-course radiation, Dr. Romesser said.

Going forward, Dr. Romesser said he’ll tell patients about the findings of this study and a previous report published in 2022 that determined that “organ preservation is achievable in half of the patients with rectal cancer treated with total neoadjuvant therapy, without an apparent detriment in survival, compared with historical controls treated with chemoradiotherapy, TME [total mesorectal excision], and postoperative chemotherapy.” Dr. Smith is a coauthor of that study.

“Generally, I’ll steer patients toward long course, assuming all else is equal, and it’s not an undue burden on them financially and socially to come in for 5-6 weeks of chemoradiation,” Dr. Romesser said. He added that, “generally, the insurance companies recognize [short-course and long-course radiation] as both acceptable and standard treatment options for patients. We haven’t found that insurances will approve one, but not the other.”

The study was funded by the National Institutes of Health. Dr. Romesser disclosed consulting/advisory roles (EMD Serono, Faeth, Natera), research funding (XRad), and travel/accommodations/expenses (Elekta). Dr. Smith disclosed consulting/advisory roles (Foundation Medicine, Guardant Health). The other study authors reported no conflicts of interest.

The Gastrointestinal Cancers Symposium is sponsored by the American Gastroenterological Association, the American Society for Clinical Oncology, the American Society for Radiation Oncology, and the Society of Surgical Oncology.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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