People who have been treated for cancer as adolescents or young adults are twice as likely as their peers to develop new tumours years later, according to a new Alberta study that reinforces the need for better screening of an often-forgotten cohort.
The research, published Monday in the Canadian Medical Association Journal, looked at what happened to nearly 25,000 young adults in the Prairie province who were first diagnosed with cancer between 1983 and 2017.
Nearly 6 per cent of them went on to develop a new cancer (as opposed to a recurrence of their original cancer, which was not the focus of the study). Many of those fresh tumours emerged after patients had passed the five-year survival benchmark and had been discharged from the cancer system.
“Oftentimes they’re not provided with any information about what surveillance they’re meant to be undergoing,” said Miranda Fidler-Benaoudia, a cancer epidemiologist with Cancer Care Alberta and one of the authors of the new study. “Many family doctors do not know what the complex care needs are of a young cancer survivor because it’s so rare.”
Cancer doctors have long known that radiation, as well as some types of chemotherapy and hormone therapy, raise the risk of subsequent cancers. On top of that, some survivors of young adult cancer have lifestyle or genetic risk factors that predispose them to another cancer.
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But Dr. Fidler-Benaoudia said much of the scientific literature about subsequent cancer risk among young adults is extrapolated from studies of childhood cancer survivors, who tend to be followed more closely by health care systems in Canada and other countries than patients first diagnosed in their 20s or 30s.
Young adults “fall through the cracks of a lot of the research,” she added, noting that most cancer studies focus on adults over 50, the cohort likeliest to get cancer.
Although rates of several cancers are rising among people in their 20s, 30s and 40s, the disease remains much more common in senior citizens and the elderly.
The new Alberta study found that survivors of Hodgkin lymphoma and breast cancer were most at risk for new cancers, likely because both diseases are often treated with chest radiation, a risk factor for future tumours. By 30 years after their initial diagnosis, a quarter of them had another cancer, Dr. Fidler-Benaoudia said.
The study also revealed that the median age at diagnosis for subsequent cancers in adolescent and young adult survivors is lower than the age at first diagnosis for the general Canadian population, which suggests survivors could benefit from screening at younger ages.
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Rigorous screening is already available to survivors of pediatric cancer, according to Abha Gupta, medical director of the adolescent and young adult cancer program at the Princess Margaret Cancer Centre in Toronto. She was not involved in the new study.
Long-term follow-up for childhood cancer survivors is a “well-oiled machine,” Dr. Gupta explained, with clear North American guidelines and dedicated clinics designed to meet their needs, regardless of cancer type.
Young adults don’t have the same level of consistent support across Canada, where policies on screening cancer survivors differ from province to province.
Ontario, for example, has a high-risk breast cancer screening program that offers annual mammograms and breast magnetic resonance imaging to people who had chest radiation to treat another cancer, such as Hodgkin lymphoma, before the age of 30 and at least eight years ago.
Work is under way to develop a high-risk breast cancer screening program in Alberta, according to the study, but for now it’s not available there or in several other Canadian jurisdictions.
“It should be implemented across the country,” Dr. Gupta said.
Tyler Cavanaugh, 34, agrees. He was diagnosed with non-Hodgkin lymphoma at the age of 27 and was a patient adviser for the Alberta study.
“If you’re diagnosed as a pediatric you’re kind of followed in some capacity for the rest of your life, but the minute you cross over into adulthood you get five years and that’s it,” he said. “I think future screening and prevention methods would certainly go a long way.”