According to a new study on cancer
trends in Canada
from 1971 to 2015 published in CMAJ (Canadian Medical Association)
,the overall rate of new cancer cases is decreasing in men but increasing in women younger than 80 years, and obesity-related cancers
are increasing in young people, according to a study on cancer
Dr. Darren Brenner, Cumming School of Medicine, University of Calgary, one of the coauthors told Thailand Medical
News, "The most striking results from these analyses relate to increasing incidence trends among younger adults for breast, colorectal, pancreatic, endometrial and kidney cancers
. Obesity is a risk factor for these cancer sites, and the rising incidence runs parallel to the growing prevalence of obesity in recent decades."
The new study, which included almost 5.2 million cancer cases diagnosed in Canada
between 1971 and 2015, looked at cancer trends by age and birth cohort (patients grouped by year/decade of birth). Cancer
incidence ie the rate of new cases is well documented in Canada
, but less is known about trends by age groups.
The authors said,"The trend among younger adults is of greater concern because they are ineligible for most cancer
Major findings of the study are:
-There has been an overall increase in cancers
not normally occurring at younger ages, particularly breast and colorectal cancer
-The highest increase in cancer
incidence is for women aged 30-39 years.
incidence has decreased in women aged 80-89 years.
-The most recent trends show statistically significant decreases in the incidence of cervical, lung, bladder and prostate cancer
, across most age categories.
-The overall recent decrease in cancer
incidence is due to declines in cancer
in people older than 50 years.
The overall reductions in cancer
incidence across age groups for several cancer
types are most likely the result of primary and secondary prevention activities, including smoking cessation programs, which have decreased lung cancer
, and sun safety behaviours, which have led to lower rates of melanoma in women younger than 40 and in men younger than 50 years.
Endoscopy and fecal-based screening programs for colorectal cancer
and screening for cervical cancer
have contributed to declining rates in these cancers
But a rise in the use of prostate-specific antigen (PSA) testing resulted in sharp increases in prostate cancer
diagnoses between 1990 and 2007, and thyroid cancer
has also been over-diagnosed.
Also ,age-specific can
rates over time help identify the impact of changes in practice such as screening programs, better diagnosis and changing risk factors. Further efforts to reduce obesity, promote additional cancer
prevention programs and further research into risk factors that may be causing cancer
in younger age groups are essential.
Reference: "Age-standardized cancer-incidence trends in Canada, 1971-2015" is published November 18, 2019, CMAJ (2019). https://www.cmaj.ca/lookup/doi/10.1503/cmaj.190355