by Paul Mayne, University of Western Ontario

Cancer cell during cell division. Credit: National Institutes of Health

A cancer diagnosis is tough enough to hear, but a diagnosis that cancer has spread through the body has often been considered a death sentence.

Now an international study, led by Western oncology professor David Palma and researchers at Lawson Health Research Institute, is challenging that notion.

The study shows targeting high-dose radiation against cancer that has spread to five or fewer sites can extend patients' survival by more than a year.

"We were hoping to show that it was beneficial, but we didn't know," said Palma. "There has been quite the debate in the oncology community, but now the results are definitely better than we expected. It's refreshing to see such a good outcome from a study.

"In the past, the spread of lung cancer to the bones or breast cancer to the brain was considered incurable.

The study, called SABR-COMET, was the first randomized phase II clinical trial of its kind. It included 99 patients with cancer that had metastasized, spread to as many as five different places in the body.

Research participants were recruited from across Canada, Australia, the Netherlands and Scotland, including 51 patients from the local London Regional Cancer Program, with the majority having had either lung, prostate, breast or colon cancer.

The study examined the use of stereotactic ablative radiotherapy (SABR), which precisely delivers radiation to a tumour in substantially higher doses than normal with the goal of destroying cancerous cells.

"We are realizing that maybe, if someone only has a few spots of cancer spread, it's not the same as if they have 20 or 30, but also, the technology has improved and our ability to deliver radiation precisely is enormously different than it was 20 years ago," said Palma.

Median survival for patients who received SABR was 41 months compared to 28 months for those who received standard treatment. SABR also doubled the amount of time patients lived without further cancer growth – a median of 12 months for patients receiving SABR and six months for those not.

After five years, almost half the patients treated with SABR were still alive compared to 24 per cent of those who received standard treatment. Palma said the research team intends to follow up with these patients at the 10-year mark for survival rates.

Palm also emphasized there were no differences in quality of life between patients treated with SABR and those who received standard treatment, however SABR was associated with more negative side effects such as fatigue, muscle and joint pain, difficulty breathing 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 Dr. 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 patients with cancer that has spread to as many as five sites.

Palma and his research team are now planning next to assess the use of SABR in patients with cancer that has spread up to ten sites. The study, called SABR-COMET-10, is anticipated to launch by early 2019.

Palma said he often uses a baseball analogy when he talks about the idea of research.

"You swing and sometimes you strike out, sometimes you get a hit. In the end we are all just trying to get up there and take a swing and anything above that is a bonus," he said, adding the results are gratifying for the team. "You don't get a hit if you don't swing."

Provided by University of Western Ontario