By age 45, more than 80 percent of childhood cancer survivors will face serious or life-threatening effects from their treatments. These repercussions range from heart disease to colorectal and bone cancer, according to a recent Canadian study.

The study, published Monday in the Canadian Medical Association Journal (CMAJ) , found that adult survivors of childhood cancer are at increased risk of illness and death compared to the general population.

The risk of colorectal cancer is two to three times higher than in the general population. Furthermore, women who received thoracic radiotherapy during childhood have a risk of bone cancer similar to that of individuals with a genetic mutation that predisposes them to the disease.

“I think people believe that you treat a kid with cancer, cure him, and then it’s fantastic and we move on,” said Dr. Paul Nathan, study co-author and oncologist in the department of hematology and oncology. at SickKids in Toronto.

“But the problem is that we cure them with chemotherapy, radiotherapy, surgery or very heavy transplants, often a combination that results in long-term problems,” he told Global News.

About 1,000 children get cancer every year in Canada, according to a 2021 study by the Public Health Office of Canada (PHAC) . But almost 84 percent of children survive a cancer diagnosis after five years.

Although the survival rate is high, Nathan said, children are particularly vulnerable to cancer treatment because their bodies and organs are still developing. Chemotherapy and radiation, as crucial as they are, can trigger long-term side effects that manifest years later. Despite this, Nathan noted that many cancer survivors may remain unaware of these potential complications.

The Ontario-based researchers said they were very aware of the challenges surrounding screenings following childhood cancer treatments, which is why they decided to explore the data to see how many people were taking them up.

Researchers analyzed data from Ontario on 3,241 childhood cancer survivors diagnosed between 1986 and 2014. Focusing on those exposed to radiation treatments or certain chemotherapies, the study assessed their increased risk of bone cancer, colorectal cancer or cardiomyopathy (heart disease). ).

Of the entire group, 2,806 (87 percent) were at risk for at least one of these late effects, 345 (11 percent) were at risk for two, and 90 (three percent) were at risk for three late effects.

“We have shown conclusively that if you have had certain chemotherapies, radiotherapy or bone marrow transplants, the risk of these late effects or late toxicities is even higher,” Nathan said.

The North American Children’s Oncology Group has developed a series of long-term guidelines designed to monitor adults who have battled cancer during childhood.

For example, people exposed to radiation therapy to the head, brain, neck or post during childhood are at risk of thyroid cancer. For this reason, the guideline recommends annual thyroid exams.

Women who received chest radiation during childhood may also face an increased risk of bone cancer, and annual breast exams beginning at puberty are recommended, along with annual mammograms eight years after radiation.

In terms of chemotherapy when young, there are several potential late effects, including acute myeloid leukemia (AML), which is cancer of the blood and bone marrow. Annual physical examinations are recommended after exposure to the agent.

Although the guideline exists, the CMAJ study authors say the number of survivors who followed screening recommendations was low. The study found that only 13% met colorectal cancer screening recommendations, 6% followed bone cancer screening guidelines and 53% adhered to cardiomyopathy screening recommendations.

Those older at diagnosis were more likely to follow cancer screening guidelines. In contrast, the study concluded, younger age at diagnosis was uniquely associated with a greater likelihood of following cardiomyopathy screening guidelines.

Regarding the age at which these complications appear, Nathan said it depends on the patient.

“They can intervene at any time. Some of our patients have these problems since the beginning of treatment and they persist throughout their lives. But for many of them, they only develop later,” he said. “There is a period when the damage is subclinical or we cannot see what is happening until it manifests. And that could take years or decades.”

Dr. Jennifer Shuldiner, study co-author and observer at Women’s College Hospital in Toronto, said the guidelines are too complex, too long and are also constantly changing.

To use the guidelines, the patient or doctor must also know the treatment received during childhood, which may have been decades ago, she said.

“Therefore, a person may often not know what treatment they received. And therefore, if they have a family doctor, the family doctor may not have access to this information or may have difficulty finding it. So this complicates the situation,” Shuldiner added.

In Canada, there are numerous clinics available for childhood cancer survivors, although they are mainly located in large cities. And for patients in their 30s, 40s or 50s, who are significantly removed from cancer treatment, she said attending entourage appointments can present challenges. Factors such as lack of awareness about risks, accessibility issues and associated costs (childcare or parking fees) can contribute to patients abandoning these appointments.

The study found that despite primary care physician visits, survivors’ adherence to bone cancer and colorectal cancer surveillance guidelines was low. Primary care physician visits were uniquely associated with greater adherence to cardiomyopathy surveillance.

“This may reflect practical barriers; In comparison with other surveillance tests, echocardiography is more readily available and less restrictive for primary care physicians in Ontario than a multi-target stool DNA test,” the authors said.

Based on the findings, researchers said they will soon launch a province-wide study to see if surveillance reminders to childhood cancer survivors and their family doctors will complete these potentially life-saving tests.

“It would use the same process by which people receive reminders for colon cancer screenings, Pap smears or bone cancer screenings, which currently happens in the universal population in Ontario and also happens in the high-risk population,” Nathan explained.

The theory, he said, would be to contact these high-risk groups and their doctors, reminding them of the necessary tests.

“We hope that if we can show that the system works and is cost-effective, that an organization like Ontario Health will be willing to accept it as one of the programs,” he said, adding that it will be a bonus if other provinces follow. suit.