By Dennis Thompson
Health Day reporter
TUESDAY, June 6, 2023 (HealthDay News) — A pair of new clinical trials show that radiation therapy may not be necessary to treat some forms of rectal cancer and lymphoma, sparing patients the toxic treatment.
A trial has shown that rectal cancer patients whose tumors shrink as a result of chemotherapy can safely skip radiation therapy, which is usually used before surgery, researchers reported at the American Society of Clinical Oncology (ASCO) annual meeting in Chicago.
“We can successfully ease the treatment of rectal cancer and achieve the same high cure rate—keeping patients disease-free with less long-term toxicity,” said lead author Dr. Deb Schrag, MD, chief of medicine at Memorial Sloan Kettering Cancer Center. New York City.
In the second trial, researchers found that some people with lymphoma whose cancer responds to chemotherapy and immunotherapy may not necessarily need radiation.
Radiation therapy is often used to kill cancer cells or slow their growth, but it also damages many healthy cells. As a result, it can have serious long-term health consequences for patients.
For example, radiation therapy can lead to many heart problems later in life, said Dr. Julie Gralow, ASCO’s chief medical officer.
“We cure these patients, they get radiation in their mid-30s, and then in their 50s they develop serious heart problems from the radiation,” Gralow said.
“So they’re looking at whether we can skip the radiation and still have the same excellent long-term survival?” Gralow continued. “In these cancers where we’re doing well with other treatments, the question is can we step back from the radiation and improve the side effects of the patients? Can we manage with less?”
For rectal cancer, pelvic radiation can damage the bowel, bladder and sexual function and increase the risk of future pelvic fractures, Schrag said at an ASCO news conference Saturday.
It also “can cause infertility and early menopause, which is a big deal because we’re seeing more and more rectal cancer diagnoses in people before the age of 50,” Schrag explained.
Worldwide, about 800,000 new rectal cancer diagnoses are expected in 2023, including about 48,000 in the United States, Schrag said.
The typical standard of care for locally advanced rectal cancer involves five and a half weeks of radiation therapy to the pelvic area, followed by surgery, followed by four months of chemotherapy, Schrag said.
This clinical trial shook up that process.
Randomized patients first underwent chemotherapy, and if their tumors shrunk, they went straight to surgery, with the option of further chemotherapy. Patients in this group who did not respond to initial chemotherapy received radiation therapy before surgery.
“What really motivated us was that there have been tremendous advances since radiation became the standard of care—better chemotherapy, better surgical technique, more screening—so we’re finding more tumors when they’re smaller and easier to treat, better imaging. we can separate the good ones from the really bad ones,” Schrag said. “So we asked if we could use radiation more selectively and give it only to those who don’t respond to chemotherapy, rather than giving radiation to everyone as part of the standard. [treatment]?”
During the study, 585 patients received this new treatment regimen, while another 543 patients received the usual treatment procedure.
It found that disease-free survival was about the same in both groups — about 81% in the chemo and surgery group, compared to about 79% in the radiation group.
The results showed that more than nine out of 10 patients in the chemo and surgery arm responded to chemotherapy and did not require radiation at all.
“Importantly, only 9% of patients in the intervention arm needed radiation,” Schrag said.
Dr. Pamela Kunz, director of the gastrointestinal cancer center at Smilow Cancer Hospital and Yale Cancer Center in New Haven, Conn., said the rectal cancer clinical trial is “practice changing.”
“The important thing here is that radiation can be safely omitted in many patients with locally advanced rectal cancer,” Kunz said at the ASCO briefing. “It really is ‘less is more.’ And the study shows that some patients can be spared radiation without compromising efficacy. This improves quality of life and reduces side effects, including early menopause and infertility.”
The lymphoma clinical trial included 268 patients whose imaging showed that their cancer responded well to chemotherapy and immunotherapy. They all had primary B-cell lymphoma, an aggressive cancer that occurs more often in young adults.
About half were also randomly assigned to radiation therapy, while the other half were simply observed to see if radiation was needed.
Patient survival without cancer progression was about the same in both groups at 30 months — 98.5% in the radiation group and 96.2% in the observation group.
Overall, patients in complete remission had a survival rate of 99% at 30 months, regardless of whether they received radiation therapy.
“This means that these patients can safely forego radiation and its side effects without jeopardizing survival,” ASCO’s Dr. Corey Speers said in a news release.
The results of the rectal cancer study were also published by the New England Journal of Medicine and the Journal of Clinical Oncologyin addition to the ASCO presentations.
Results presented only at a medical meeting should be considered preliminary until published in a peer-reviewed journal.
The American Cancer Society knows more about the side effects of radiation therapy.
SOURCES: Deb Schrag, MD, MPH, chair, medicine, Memorial Sloan Kettering Cancer Center, New York City; Julie Gralow, MD, Chief Medical Officer, American Society of Clinical Oncology; Pamela Kunz, MD, director of the Gastrointestinal Cancer Center at Smilow Cancer Hospital and Yale Cancer Center, New Haven, Conn.; New England Journal of MedicineJune 4, 2023; Journal of Clinical OncologyJune 4, 2023