Liver, thyroid cancer rates increasing in Canada: report
Doctors should consider the possibility of cancer in young people and be particularly vigilant about thyroid and liver cancers, say researchers who reviewed the latest Canadian cancer statistics.
Loraine Marrett of Cancer Care Ontario and her colleagues reviewed the 2008 edition of Canadian Cancer Statistics. The results of their review are published in Monday's online issue of the Canadian Medical Association Journal.
"Given the rising rates of thyroid cancer in men and women, as well as liver cancer in men, clinicians should be vigilant for these cancers," the researchers said in their recommendations to health care providers.
After standardizing for age, the average incidence of liver cancer increased by 2.7 per cent a year for men between 1995 and 2004. The incidence of thyroid cancer went up by 5.5 per cent a year among men in that time and 10.1 per cent among women, the researchers reported.
The report's authors suggested that although the risk of cancer is low, it is increasing among younger adults.
"It is becoming increasingly important to be vigilant about cancer in women, especially among those aged 20–59 years, as the incidence of breast, cervical, lung and thyroid cancers and melanoma continues to drive cancer rates in this group," the researchers wrote.
"Early detection of cancer through regular screening, along with effective treatment, can help reduce the severity of disease and mortality from cancers such as colorectal, cervical, prostate and breast."
Early detection stressed
Improvements in early diagnosis and treatment have led to declining mortality rates for all cancers combined as well as for certain types of cancer, after accounting for age.
The mortality rate for breast cancer for example has fallen by more than 25 per cent since 1986, likely the result of a combination of more mammography screenings and the use of better therapies after surgery, the researchers said.
The authors of the study also called on doctors to promote healthy lifestyles and recommended cancer screenings.
The change in the incidence rate of thyroid cancer is probably largely due to better detection of small cancers. Survival for thyroid cancer is excellent, the team said, likely because treatments are highly effective when it is detected early.
Thyroid cancer is one of the few cancers that occurs more frequently in women than in men, at a ratio of nearly four to one, the researchers said. It is also one of the most common cancers in young women, ranking second after breast cancer in women age 20 to 49.
The relatively low but increasing rates of liver cancer and mortality for that type of cancer, particularly among men, are likely related to the prevalence of hepatitis B and C infections, the researchers said.
"This may, in part, be because of changing patterns of immigration, whereby an increasing proportion of the population was born in countries where hepatitis B is endemic or where exposure to liver toxins, such as aflatoxin, are common," the study's authors wrote.
In Europe and the United States, it is estimated that about 22 per cent of primary liver cancers are attributable to hepatitis B infection and 60 per cent to hepatitis C infection, the researchers said. Alcohol-related cirrhosis and obesity accounted for other cases.
Clinicians also need to be aware of the late appearance of side-effects from treatment, second and recurrent cancers and issues related to surviving cancer, given that nearly three per cent of Canadians have received a cancer diagnosis in the last 15 years, the study's authors said.