Cancer experts say a study highlights the need for more support and screening of people who survived cancer as adolescents and young adults, as they face an increased risk of getting cancer again later.
Senior author Miranda Fidler-Benaoudia, a cancer epidemiologist at the University of Calgary and Cancer Care Alberta, said the research counted the development of new cancers — not recurrences of their original cancers — in Alberta patients who had first been diagnosed between the ages of 15 and 39.
The study, published in the Canadian Medical Association Journal on Monday, found they were twice as likely to develop another cancer as the general population.
One of the main suspected causes of subsequent cancers is treatment used for the first one, she said.
"There really is a delicate balance between cure and long-term quality of life. Radiation is a recognized cause of cancer," Fidler-Benaoudia said.
"Whilst the radiation is necessary to treat those original cancers, it simultaneously increases the risk of developing another cancer because that part of the body has been irradiated," she said.
"Similarly, there is research that shows that chemotherapy and even some hormone therapies that are used to treat cancers can cause subsequent cancers later in life, too."
Fidler-Benaoudia said that as cancer treatments evolve, the hope is that they will be less likely to be carcinogenic.
The increased risk of a subsequent cancer is not only due to past treatments, she said, noting that genetics can also play a role.
The study analyzed data from the Alberta Cancer Registry for patients who were diagnosed between Jan. 1, 1983 and Dec. 31, 2017.
Among the 24,459 survivors of cancer during adolescence and early adulthood studied, 1,442 got another cancer. In a cohort of that size in the general population, only 643 cancers would be expected, Fidler-Benaoudia said.
Breast, colorectal, and lung cancers were the most common cancers that survivors later developed, the study said.
The findings come as cancer among young people in Canada is increasing by 1.3 per cent a year, the researchers said.
Provincial governments should consider providing cancer screening at younger ages for survivors to catch subsequent cancers early, they said.
Dr. Abha Gupta, medical director of the Adolescent and Young Adult oncology program at University Health Network's Princess Margaret Cancer Centre in Toronto, said such screening programs are critical.
Gupta, who was not involved in the study, pointed to Ontario's high-risk breast cancer screening program for patients who had radiation therapy to the chest to treat another cancer before age 30.
"We know that females who undergo radiation to their chest, either for lymphoma or breast cancer or any other type of cancer, are at a significantly increased risk of developing secondary radiation-associated breast cancer," she said.
Gupta said radiation treatment is "very different" now than what was used in the 1980s and 1990s, so there may be a "slightly less risk" than the study suggests among patients who had radiation more recently.
"I think that the risk is not the same for everybody who had a cancer. The risk is very dependent on what your actual exposure was at the time of your first cancer," she said.
Patients in the 15 to 39 age group need specific programs and supports that match where they are in their lives, Gupta said.
Staff in her program "help empower patients to be able to ask their health-care providers questions, you know, about their sexual health, about their fertility, about how they're coping, about their social isolation that they feel because they have cancer and none of their peers do."
Providing psychological support is also critical as patients grapple with both the fear of their cancer returning and the knowledge that they are at higher risk of getting another cancer down the road, Gupta said.
That support can be provided by psychologists, social workers and counsellors, but bringing adolescent and young adult patients together through in-person events or online chats is also valuable so they can talk through their experiences with peers who understand, she said.
Gupta said she's seen more adolescent and young adult programs starting up in cancer centres across the country in recent years, including in other parts of Ontario, B.C., Alberta and Quebec.
