Aggressive Radiation Therapy Improves Survival in Patients with Metastatic Cancer

A high dose of precision radiation could drastically increase the survival rates of patients with metastatic cancer, and double the time patients live without cancer growth, according to study results presented at the 60th Annual Meeting of the American Society for Radiation Oncology.

Usually, metastatic disease is considered incurable, but one theory suggests otherwise. “There’s a theory — called the oligometastatic theory — that if a patient only has a few spots of cancer returning, those spots could be killed with radiation or surgery to improve their survival,” lead author David Palma, M.D., Ph.D., from Lawson Health Research Institute, explained in a statement.

The phase 2, open-label multi-center SABR-COMET study was created to challenge this theory by examining the effects of highly precise radiation therapy in 99 patients from four countries (Canada, Scotland, the Netherlands and Australia).

All patients had previously treated cancer that returned in new sites. The most common malignancies were breast (18 patients), lung (18 patients), colon or rectum (18 patients) and prostate (16 patients) cancers.

Between February 2012 and August 2016, participants were randomly placed into one of two treatment arms: a control arm that received palliative standard of care and an arm that received the standard of care plus stereotactic ablative radiotherapy (SABR), a high-precision therapy that delivers substantially higher doses of radiation to the tumor in fewer treatment sessions — usually one or just a few. The median follow-up time was 27 months.

In addition to living longer without cancer growth, researchers ultimately found that patients who received stereotactic radiation also lived considerably longer than those who did not.

Patients in the radiation arm saw a median progression-free survival of 12 months compared to six months in those who received standard of care. Median overall survival in those who received radiation was 41 months, versus 28 months in the control group.

“We were surprised and quite pleased,” said Palma. “We didn’t expect the survival benefit to be quite so long for patients with metastatic disease.”

“Now, we’ve been able to show, for the first time in a randomized trial, that high-dose radiation can effectively treat these limited recurrences, and we’ve been able to increase survival by a median of 13 months.”

There were no differences in quality of life between the two treatment arms; however, the researchers noted that radiation therapy does have drawbacks such as more negative side effects. The most common side effects noted in this study included fatigue, difficulty breathing and muscle and joint pain. Nine percent of patients in the standard of care arm and 30 percent of those who received radiation reported serious side effects.

While three patients in the radiation arm died due to side effects — one from a pulmonary abscess, one from subdural hemorrhage after surgery to repair a stereotactic ablative radiotherapy-related perforated gastric ulcer and one from radiation pneumonitis. However, the researchers noted that such events can occur with standard radiation therapy and are rare.

“Stereotactic radiation therapy needs to be delivered carefully and by an experienced team, and there is a small risk of very serious side effects, as well as mortality,” explained Palma. “But overall, for patients whose cancers have spread, and who are not expected to survive otherwise, the overall survival benefit of SABR appear to outweigh these risks.”

Because 46 percent of the patients who received stereotactic radiation were still alive after five years — compared to 24 percent of patients in the control group — this kind of treatment is worth consideration and could offer hope for some, Palma said.

“Stereotactic radiation therapy can increase how long these patients live and how long they live without their cancer coming back,” he added. “and it doesn’t seem to have a detrimental impact on their quality of life.”