October 25, 2010 – “Cancer screening is a lottery: rare are the big winners whose lives are extended thanks to it, and there are a few rare big losers, who are either wrongly reassured not to have cancer, or treated unnecessarily, ”said Dr.r Michel Labrecque at the recent Symposium on French-speaking medicine1.
There is a problem of perception with regard to screening, within the population, adds the Dr Labrecque. “The message we’re presenting is based on the equation that screening saves lives. This is sometimes true, but there is a downside: all screening programs do harm, some do good and some at a reasonable cost, ”he said.
Prostate cancer: 1 life saved in 1,000 men screened
Based on Canadian cancer statistics cited by Dr.r Labrecque, the risk of developing prostate cancer during a man’s lifetime is 14%. The risk of dying is 4%.
Dr Michel Labrecque
According to the most optimistic data from recent studies, out of 1,000 men aged 60 (with no family history) who are screened for prostate cancer each year (PSA test and digital rectal exam), 1 less man would die of this cancer over a period of 10 years.
According to a study cited by Dr Labrecque, the risk of dying from heart disease is 2 to 11 times higher than that of dying from prostate cancer, in those who are diagnosed with this cancer; one week after the diagnosis.
Even more disastrous, the risk of suicide – one week after a diagnosis of prostate cancer – would be 8 times higher than that of dying from this cancer, when the diagnosis is announced before the age of 54 years. The results of this study, however, remain to be demonstrated, according to Dr Labrecque.
Breast cancer: a few prolonged lives out of 1,000 women screened
In women, the risk of developing breast cancer in their lifetime is 12%. The risk of dying from it is 3%.
In absolute terms, out of 1,000 women aged 50 (without a family history) screened every 2 years by mammography, over a period of 10 years, 2 women will have their life prolonged beyond 60 years and it is estimated that 7 could extend their life up to 85 years, through screening.
According to the rigorous international scientific publication Cochrane, “It is not clear that breast cancer screening does more good than harm,” said Michel Labrecque.
And, according to a report published in 2009 by the US Preventive Services Task Force (USPSTF), “There is moderate certainty that there is a moderate net benefit from screening for breast cancer every 2 years in women aged 50 to 74.”
What about mammography for women aged 40 to 49? “In 2009, the Agency for the Evaluation of Technologies and Methods of Intervention in Health (AETMIS) advised against including women aged 40 to 49 in the Quebec breast cancer screening program,” recalled Dr. Labrecque.
According to AETMIS, the annual screening of breast cancer in 1,000 women aged 40 to 49, for 10 years, would save 0.9 lives, but at the same time it would cause 0.5 deaths due to radiation.
|
French-speaking medicine symposium Read also Breast and prostate cancer screening: talk to your doctor |
Martin LaSalle – PasseportSanté.net
Modified October 29, 2010
1. For more information: www.medecinsfrancophones.ca [consulté le 25 octobre 2010]
