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The numbers of cancer cases and deaths are rising in Canada, even as overall rates of cancer incidence and mortality continue to decline, new research suggested.

Cancer is still the number one cause of death in Canada; it accounted for about 25% of deaths in 2022. The new study, which was published online on May 13 in CMAJ, projects that there will be 247,100 new cancer diagnoses and 88,100 cancer deaths in 2024 : An increase from an estimated 239,100 cancer cases and 86,700 cancer deaths in 2023. Yet overall, cancer incidence continues to decline.

What's behind these trends? An aging population is likely responsible for the increase in new cases, according to study author Darren R. Brenner, PhD, associate professor of oncology at the University of Calgary, Calgary, Alberta, Canada. Contributing to the projected declines in specific cancers are "organized screening programs, such as for breast and colorectal cancer, as well as prevention activities like tobacco avoidance and smoking cessation," he told Medscape Medical News. "Many cancers have also had notable improvements in available treatments and clinical management."

A Complex Picture

The researchers analyzed data on cancer incidence and mortality from 1984 to 2020 from the Canadian Cancer Registry and Canadian Vital Statistics Death Database. They projected cancer incidence and mortality counts and rates to 2024 for 23 types of cancer overall, by sex, and by province or territory. Age-standardized incidence rates (ASIRs) and mortality rates (ASMRs) were calculated using data from the 2011 Canadian standard population.

Lung cancer is projected to be the most diagnosed cancer, with 32,100 new cases in 2024. It is expected to remain the leading cause of cancer death for men and women in 2024 (20,700).

"While progress has been made in tobacco control, lung cancer rates in 2024 are for the most part still a reflection of previous tobacco exposures," said Brenner. "This is why many provinces are implementing lung cancer screening that is focused on people with a past history of tobacco exposure."

Among men, the most common diagnoses are expected to be prostate (22%), lung (12%), colorectal (11%), and bladder (7%) cancers. Among women, breast (25%), lung (14%), colorectal (9%), and uterine (7%) cancers are expected to be most common.

Excluding sex-specific cancers, cancer was more commonly diagnosed among men than women, except for breast, thyroid, and lung cancers, which are more common among women, according to the researchers.

The ASIR for all cancers combined is expected to be 13% higher among men than women, and ASMRs are expected to be 37% higher in men than in women. "Males have historically had higher rates of negative risk factors for cancer in Canada," said Brenner. "Also, males generally report lower health-seeking behavior and follow-up for care, which often result in worse health outcomes for similar diseases than for females."

After adjustment for Canada's aging population, overall incidence and mortality rates were projected to decrease slightly from previous years for both sexes. They are projected to continue to decrease for some of the most common cancers, including lung, colorectal, and prostate.

In contrast, incidence rates of cancers that are less common, including liver and intrahepatic bile duct cancer, kidney cancer, melanoma, and non-Hodgkin lymphoma, are projected to increase.

"Each one of these cancers has a unique set of exposures that impact cancer rates over time," said Brenner. "For example, we know that liver cancers are largely driven by alcohol consumption, hepatitis B and C infection, and excess body size. This is different from melanoma, which is driven by negative exposure to ultraviolet radiation from the sun. These different sets of risk factors require different actions and efforts to stem the rising rates."

The top four cancers (ie, lung, breast, prostate, and colorectal) are expected to make up almost half (47%) of all new cases. The researchers also found that cancer mortality rates are higher in eastern Canada than in western Canada. In addition, more patients are surviving cancer, with an estimated 1.5 million in Canada living with and beyond cancer at 25 years after diagnosis.

Cause for Concern?

The growing population of cancer survivors, combined with the projected annual increase in the total number of new primary cancers in 2024, "will have a substantial impact on Canadian healthcare systems, given ongoing needs of people with a history of cancer," the study authors wrote. "The increase in the number of cancer survivors will require additional investment and innovation to provide necessary supports."

Commenting on the findings for Medscape Medical News, Talía Malagón, PhD, assistant professor of oncology at McGill University in Montreal, Quebec, Canada, said, "In general, it is encouraging that the overall rate of cancer diagnosis and mortality is declining in Canada, as it shows that years of investment into tobacco control and screening for several cancers has helped reduce cancer incidence and mortality." Malagón did not participate in the research.

"Despite these improvements, we still expect there to be many people diagnosed with cancer in the future due to an aging population, which will have a major impact on our healthcare system in the coming years," she added.

"Most concerning to me are the increase in liver and intrahepatic bile duct cancer incidence and mortality and the increase in melanoma incidence, as these are cancers that can be prevented. We need more awareness and investment into preventing the causes of these cancers, which include practicing sun safety, preventing hepatitis B and C infection, as well as reducing alcohol intake and maintaining a healthy lifestyle."

Preventive Efforts

For preventive efforts to be effective, "we need a path to rebuilding our healthcare system that ensures faster access to cancer care services when people need it," Ioana Nicolau, PhD, senior epidemiologist at the Canadian Cancer Society, told Medscape Medical News. "Primary care is the backbone of accessing cancer care services throughout someone's cancer experience…The lack of primary care providers, particularly family doctors, is alarming, and we're closely monitoring how this crisis is impacting the cancer community."

"All levels of government are responsible for funding efforts to increase awareness about cancer risk, reduce barriers to screening, and ensure that people with cancer have access to care and support throughout their cancer experience," she said. Within provinces and territories, ministries of health, departments of health, and cancer agencies also play a role in different aspects of cancer care.

The Canadian Cancer Society will continue to ask provincial and territorial governments to improve and expand cancer screening programs, said Nicolau. "We saw an important advance when the government of British Columbia announced that it will be transitioning to HPV screening as the primary form of screening for cervical cancer, as well as offering cervix self-screening options to better reach underscreened populations. We have long advocated for the implementation of HPV testing as the primary test."

In addition, Canada's federal government has signed health agreements with all provinces and territories that help boost funding for primary care. "We urge provincial and territorial governments to work with health system and charitable stakeholders to ensure that enhancements to primary care improve access to cancer care services."

In a related editorial, Keerat Grewal, MD, an emergency physician at the Mount Sinai Hospital and assistant professor at the University of Toronto, Toronto, Ontario, Canada, and Catherine Varner, MD, deputy editor of CMAJ, suggested expanding access to outpatient clinics that streamline suspected cancer diagnoses, such as Ontario's diagnostic assessment program clinics. They also recommend offering navigation support for patients discharged from the emergency department with a cancer diagnosis.

"Continued efforts to increase awareness of early cancer symptoms, reduce barriers to cancer screening, and increase capacity for its early diagnosis in primary care and hospitals are critical," the editorialists wrote. "To lose the gains made in cancer outcomes to the overcrowding, fragmentation, and inefficiencies of healthcare systems would be a tragic shame."

Canada Not Unique

The situation in Canada is mirrored in other wealthy nations. "In general, Canada is similar to the United States and other wealthy countries in terms of cancer incidence and outcomes," said Malagón. "Both are in the top 10 countries with the highest age-standardized incidence rates of cancer, according to the International Agency for Research on Cancer. Much of this is because many of the major lifestyle causes of cancer (like tobacco consumption, alcohol consumption, and excess body weight, among others) are unfortunately much more common in wealthy countries.

"However," she added, "because ASMRs have been strongly decreasing due to improved survival, as shown in this paper, high-income countries generally have better mortality outcomes than low-income countries."

Nicolau sees similarities between the United States and Canada, in that the most common cancers among men are prostate, lung, and colorectal, and among women, they are breast, lung, and colorectal.

"In the US and Canada, overall cancer mortality rates in both males and females have been declining," said Malagón.

The cancer prevalence study was developed by the Canadian Cancer Statistics Advisory Committee in collaboration with the Canadian Cancer Society, Statistics Canada, and the Public Health Agency of Canada and was therefore supported by public and donor funding. No external sources of funding were obtained. Brenner reported support from the Canadian Cancer Society and the Canadian Partnership Against Cancer. Malagon and Nicolau reported no relevant financial relationships.

Marilynn Larkin, MA, is an award-winning medical writer and editor whose work has appeared in numerous publications, including Medscape Medical News and its sister publication MDedge, The Lancet (where she was a contributing editor), and Reuters Health.