A healthcare worker tends to a patient. Share on Pinterest
A new study finds radiation may not be needed for certain forms of rectal cancer. PER Images/Stocksy
  • A new study finds some people with rectal cancer may be able to forgo radiation.
  • The trial involved more than 1,100 people with locally advanced rectal cancer, meaning it had not spread to other parts of the body.
  • After five years, researchers found that people who received chemotherapy alone before surgery did as well as those who underwent both chemotherapy and radiation before surgery.

Certain people with locally advanced rectal cancer could forgo radiation therapy with no impact on their survival, a large clinical trial showed.

Pelvic radiation therapy is a standard treatment for this type of cancer, but it can have serious side effects.

The rectum is the last several inches of the large intestine, closest to the anus. It sits inside the pelvis, which contains tightly packed organs, including the reproductive organs.

Radiation exposure in this area can cause changes in bowel habits, bladder irritation and weakening of the pelvic bones. There is also a risk of infertility, especially in women.

The results of the study were revealed in early June at the annual meeting of the American Society of Clinical Oncology and in a paper in the New England Journal of Medicine.

“The bottom line [of this study] is that radiation therapy is not necessary for some patients with rectal cancer,” Dr. Afsaneh Barzi, a medical oncologist with City of Hope in Duarte, Calif. who was not involved in the study, told Healthline.

The new method is “essentially the more favorable treatment [for these patients], because radiation has long-term side effects,” she added.

Dr. Jun Gong, a hematology oncologist at Cedars Sinai in Los Angeles was not involved in the study and said the results will have a direct impact on the treatment of this type of rectal cancer.

“This is what we call a ‘practice-changing study,’ where clinicians can take these findings and start to apply it to their patients in the clinic as soon as tomorrow,” he told Healthline.

The trial involved more than 1,100 people with locally advanced rectal cancer, meaning it had not spread to other parts of the body.

Some people were excluded from the trial because their tumors were too advanced or too low in the rectum, making them high-risk patients.

People were randomly assigned to receive either the standard treatment for this type of cancer — both chemotherapy and radiation before surgery — or chemotherapy alone before surgery.

The chemotherapy used during the experimental treatment combined three separate drugs given over six sessions. People in the standard treatment group received one chemotherapy drug.

Both groups had the option of receiving additional chemotherapy after surgery, at their doctor’s discretion.

After five years, researchers found that people who received chemotherapy alone before surgery did as well as those who underwent both chemotherapy and radiation before surgery.

Major outcomes, including disease-free survival, overall survival and the rate of the cancer returning, were almost identical between the two treatments, the results showed.

Being able to avoid radiation, without compromising survival, could mean a better quality of life for people, including reducing the risk of problems with fertility or sexual function.

As part of the study, researchers also collected data on people’s side effects and quality of life. These results were published separately June 4 in the Journal of Clinical Oncology.

People who underwent radiation-free treatment had lower rates of diarrhea and bowel function, researchers found. However, some side effects were lower in the radiation-treatment group, including anxiety, appetite loss and constipation.

Twelve months after surgery, the radiation-free group had lower rates of fatigue and nerve-related symptoms, as well as better sexual function.

Gong pointed out that the goal of the new study was not to eliminate radiation therapy entirely as a treatment for rectal cancer, but to identify a subset of patients who could benefit from skipping radiation, while preserving survival outcomes.

In fact, “this could be a clinically meaningful subset of patients,” he said, “because we see a lot of intermediate-risk rectal tumors frequently in the clinic.”

While the new treatment offers patients and doctors another option, in some cases people will still require radiation before surgery.

For example, some patients in the study who were assigned to the chemotherapy-only group ended up receiving the same chemotherapy and radiation therapy as the standard treatment group.

This included people who couldn’t complete at least five sessions of chemotherapy, such as due to the side effects of the drugs.

Also included were people whose main tumor didn’t decrease by at least 20% following chemotherapy with the six drugs — which happened just 9 percent of the time.

This aspect of the study protocol ensured that people in the experimental group would receive the most effective treatment for their specific situation.

“This was kind of a built-in safety plan,” said Gong, “because the investigators wanted to make sure they were not compromising efficacy.”

Given the number of people potentially eligible for the new treatment, Barzi said the impact of the study on rectal cancer treatment would be “sizable.”

Around 46,000 people are diagnosed with rectal cancer each year, according to the American Cancer Society.

“We believe around 20,000 of them — who have stage 2 or 3 cancer — could benefit from this approach that can spare them from having to get radiation in addition to chemotherapy and surgery,” study author Dr. Deb Schrag, a gastrointestinal oncologist at Memorial Sloan Kettering Cancer Center in New York City, said in a news release.

The results are especially relevant for people who are diagnosed with rectal cancer at young ages, when preserving fertility is an important concern.

“About 30% of patients with rectal cancer are under the age of 50,” said Barzi. “These are younger people, so the findings of this study — including the quality of life components — may actually be important for their decision making.”

There are also differences in the intensity of the treatments that could affect people’s decisions about which treatment to choose.

Chemotherapy and radiation before surgery requires 28 daily visits over five-and-a-half weeks. Chemotherapy alone, as done in the new study, requires only six visits over 12 weeks.

For people who choose only chemotherapy before surgery, “there is some freedom, in terms of scheduling, that is of value,” said Barzi, “especially in the context of patients who are younger — who are in the formative years of their lives, and may be in school or have work.”

Overall, “[the new treatment method] is a welcome addition,” she said, “and provides another option for patients, and another opportunity for shared decision-making between patients and their physicians.”

In addition to the patient, Gong said treatment decisions should include a multi-disciplinary healthcare team of medical oncologists, radiation oncologists, surgical oncologists and pathologists.

“The whole team will still decide which patients are candidates for the [new] regimen or other treatment routes,” he said.