The overall rate of cancer diagnosis is declining in Canada, but an aging and growing population means the number of cases and deaths due to the disease are estimated to rise, according to a new study. The projected cancer rates for 2022 expect lung cancer to account for nearly a quarter of all cancer deaths.
The study, published on Monday in the Canadian Medical Association Journal (CMAJ), estimates that 233,900 new cancer cases will be diagnosed in Canada this year, up from an estimated 229,200 cases in 2021. An estimated 85,100 deaths are projected for 2022, up from 84,600 last year.
“The impact of cancer on the Canadian population and health care systems is substantial. Cancer is the leading cause of death in Canada,” the authors wrote in the study, which was developed by the Canadian Cancer Statistics Advisory Committee and conducted in collaboration with the Canadian Cancer Society, Statistics Canada and the Public Health Agency of Canada.
“With an aging and growing population, the number of new cancer cases and deaths in Canada is also increasing. In addition to its impact on health, cancer is costly. The economic burden of cancer care in Canada rose from $2.9 billion in 2005 to $7.5 billion in 2012, annually.”
The authors noted that the potential impact of COVID-19 on cancer incidences and mortality were not included in the study’s projections. Earlier this year, an Ontario report found a 34 per cent drop in people being diagnosed with cancer in the province in 2020 during the first waves of the pandemic, likely due to an overwhelmed health-care system and fewer visits to the doctor. The sharp decline has raised concerns over the consequence of detecting cancers at later stages.
In the latest study, an estimated 24.3 per cent of cancer deaths are expected to be attributed to lung cancer, while colorectal cancer is expected to account for 11 per cent, researchers said. Pancreatic cancer is projected to make up 6.7 per cent of deaths, while breast cancers are estimated to account for 6.5 per cent of deaths.
“The projected high burden of lung cancer indicates a need for increased tobacco control and improvements in early detection and treatment,” the paper said, noting that smoking rates were higher especially among individuals with lower income, those living in rural areas, and First Nations, Inuit and Metis people.
“Success in breast and colorectal cancer screening and treatment likely account for the continued decline in their burden. The limited progress in early detection and new treatments for pancreatic cancer explains why it is expected to be the third leading cause of cancer death in Canada.”
Researchers made projections for 22 types of cancers, broken down by sex and geography, and found that four leading types of cancers will account for 46 per cent – nearly half – of all new cancer diagnoses this year: 30,000 cases of lung cancer, followed by 28,900 cases of breast cancer, 24,600 cases of prostate and 24,300 cases of colorectal cancer.
Eastern provinces are generally projected to have a higher rate of incidence and mortality than western provinces, according to the study.
Among men, one in five diagnoses will be for prostate cancer, followed by lung cancer. Among women, breast cancer accounts for one in four diagnoses, also ahead of lung cancer at 13 per cent of cases.
An estimated 43 per cent of Canadians will be diagnosed with some form of cancer in their lifetime, according to the 2021 Canadian Cancer Statistics report, killing more Canadians than any other source. After adjusting to standardize the age groups, males were estimated to have a 34 per cent higher mortality rate than females.
Despite these numbers, however, the prognosis for many forms of cancer has improved significantly over the last 30 years.
“Cancer control efforts are having an impact on cancer in Canada,” said co-author Dr. Darren Brenner, an epidemiologist at the University of Calgary’s Cumming School of Medicine, in a statement.
“The overall age-standardized rates of new cases and deaths continue to decline, in large part because of efforts in cancer prevention, screening, early detection and treatment. There has also been an overall increase in survival among people in Canada diagnosed with cancer, which is good news.”
The study is based on data from the National Cancer Incidence Reporting System from 1984 to 1991 and the Canadian Cancer Registry from between 1992 and 2018 for new incidences. The Canadian Vital Statistics’ Death Database was used for mortality data from 1984 to 2019.
The authors said while the most recent and complete data available was used for their analyses, the complexities around registration and verification of cancer means that there is a considerable lag in data collection.
“We anticipate that measures to combat the spread of COVID-19 have affected many cancer-control activities in Canada. Interruptions in screening programs and diagnostic pathways may have led to a reduction in diagnoses and may result in a shift in some cancers to more advanced stages,” the authors wrote, adding that they expected the pandemic disruption would eventually balance out over the long term.
“We hypothesize that the shift to later-diagnosed cancers and any pandemic-related delays in treatment will affect mortality and survival.”