Study looks at potential complications of radiation therapy for prostate cancer
Published Thursday, January 16, 2014 6:42PM EST
Last Updated Thursday, January 16, 2014 11:29PM EST
A new Canadian study suggests that radiation therapy may lead to a higher incidence of complications later in life, including a risk of secondary cancers elsewhere in the body.
The study, published Thursday in The Lancet Oncology, found that prostate cancer patients who were treated with radiation therapy were up to three times as likely to develop a secondary cancer compared to those who underwent surgery, or compared to the general population.
The study examined health data for 32,465 Ontario prostate cancer patients who were treated between 2002 and 2009.
Of those patients, 15,870 had surgery and 16,595 had radiation therapy. The median age of the surgery group was 62, and the median age of the radiation therapy group was 70.
The study's authors looked at five common treatment-related complications that can arise in prostate cancer patients: hospital admissions, urological, rectal or anal procedures, open surgical procedures and secondary malignancies.
Patients who were treated with radiation had a higher incidence of developing a secondary malignancy five to nine years after treatment (4.5 per cent) compared to those patients who were treated with surgery (1.8 per cent).
"Cancers of the rectum, for example, cancers of the bladder, cancers of the bloodstream that occurred… we think due to the radiation exposure," Dr. Robert Nam, the study’s lead author and a urologic oncologist at Sunnybrook Health Sciences Centre in Toronto, told CTV News.
The radiation group also had a higher incidence of hospital admissions, rectal or anal procedures and open surgical procedures, compared to those patients who had surgery.
However, patients who had surgery had a higher incidence of urological procedures compared to patients who had radiation therapy, the study found.
The researchers found that while age and other illnesses were important predictors for all of the complications, the type of treatment was the strongest predictor of having any of the complications.
Nam told The Canadian Press that the patients who received radiation had rates of complications between two and 10 times higher than patients who had surgery.
"The rates of complications… were quite significant," he said, adding that up to 30 per cent of the prostate cancer patients ended up with at least one of the complications.
Nam said the findings will have an impact on how doctors counsel patients as they navigate their treatment options.
President of the Canadian Association of Radiation Oncology Dr. Ross Halperin told CTV News in an email that the results from the study are not surprising, and are similar to the findings of other research papers.
Halperin said often patients are told radiation therapy causes DNA damage, which may lead to the development of new cancers over time.
"This is an understood phenomenon and a risk that is communicated to patients as part of a consent conversation between radiation oncologists and their patients," he said.
He added that patients who undergo radiation therapy are expected to have higher rates of secondary cancer for a number of reasons, including that they may be older and sicker, and unable to have surgery.
He said that while it is unlikely that the study’s findings will change clinical practice, it is a reminder that all treatments are associated with risks of complications.
When John McDonald was diagnosed with prostate cancer, he and his doctors chose radiation therapy and it worked. But 12 years later, doctors found cancer in his bladder. They believe it may have been caused by the radiation therapy he received more than a decade ago.
"Yes, it was a big shock, it was a big shock," he told CTV News.
McDonald has since had surgery to remove his bladder and says he has no regrets.
"I had 12 good years, I can't complain at all," he said.
Dr. Joseph Chin from the department of oncology at Western University told CTV News that it’s important that patients are aware that both radiation and surgery are effective in treating prostate cancer, and both are preferable to no treatment at all.
“This is not to scare them off (or) to refuse treatment altogether. They still need treatment and the treatment works. It's just that we have to be aware of the potential complications," he said.
“We just have to lay them out clearly, and patients can consider the pros and cons and go from there.”
With a report by CTV News' Medical Correspondent Avis Favaro and Producer Elizabeth St. Phillip and files from The Canadian Press