Dr. David Palma. Photo courtesy of Lawson Health Research Institute.Dr. David Palma. Photo courtesy of Lawson Health Research Institute.
London

High-dose radiation can increase cancer survival rate

There is new hope for cancer patients whose tumours have spread to other parts of their body.

An international study, led by London's Lawson Health Research Institute, found targeting cancerous tumours with substantially higher doses of radiation than normal can improve the chance of survival in patients whose cancer was once thought to be incurable.

Researchers looked at 99 patients with oligometastatic cancer – cancer that has metastasized or spread to five or fewer sites in the body - for the first of its kind randomized phase II clinical trial. The patients were then randomly selected to receive either the standard treatment, consisting of chemotherapy or radiation therapy, or standard treatment combined with stereotactic ablative radiotherapy (SABR).

The SABR technique precisely delivers radiation to a tumour in substantially higher doses than normal to try to destroy cancerous cells.

“In the past, the spread of lung cancer to the bones or breast cancer to the brain was considered incurable,” said Dr. David Palma, Lawson researcher and lead author on the study. “We’ve shown for the first time that if cancer has spread to only a few spots, we can target those tumours with high-dose radiation to increase how long a patient lives.”

The study, dubbed SABR-COMET, found that patients who received the higher dose of radiation lived longer than patients who did not. Median survival for patients treated with the new technique was 41 months compared to 28 months for those who received standard treatment. It also doubled the amount of time patients lived without further cancer growth.

After five years, 46 per cent of patients given the new treatment were still alive compared to 24 per cent of those who received standard treatment, according to the study.

The only downside found by researchers was an increased risk of negative side effects. While there was no difference in patient's quality of life, 30 per cent of those who received a higher dose of radiation experienced serious side effects compared to 9 per cent of patients who received standard treatment. The most common side effects included fatigue, difficulty breathing, muscle and joint pain, and bone pain.

“SABR needs to be delivered carefully and by an experienced team. While there is a small risk of very serious side effects, these are patients with limited options,” said Palma. “Ultimately, the decision to offer SABR is up to the patient’s oncologist. Physicians should at least consider it as a treatment option for oligometastatic patients.”

More than half of the study participants from Canada, Australia, the Netherlands, and Scotland, were patients at the London Health Sciences Centre's London Regional Cancer Program.

Some of those who took part developed additional tumours during the trial, that were then successfully treated. As a result, researchers now plan to launch a follow-up study that will use the SABR technique to target cancer that has spread to up to ten sites in a patient's body. That study is expected to begin in early 2019.

“We are very excited about the potential for this research to afford cancer patients longer and higher quality of life,” said Neil Johnson, regional vice president of cancer services at LHSC. “This illustrates the critical partnership of clinicians, scientists, and patients in driving translational research.”

Palma will be sharing the results from the SABR-COMET study at the 60th Annual Meeting of the American Society for Radiation Oncology on Monday.

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