Common cancer screenings aimed at detecting and treating the disease early may not be as effective in extending a person’s life expectancy as previously thought.
Researchers reviewed clinical trials involving 2.1 million people who underwent six types of common cancer tests, tracked them for up to 15 years, and compared the life expectancy of those screened and not for the disease.
They found that just screening for one cancer – colon cancer – seemed to make a difference in extending a person’s life, giving them just over three months extra compared to their peers who weren’t screened.
But the experts say that doesn’t mean you should cancel that mammogram or any other screening appointment, because other data has shown that screening reduces the risk of dying from cancer.
The study looked at all-cause deaths, not just cancer. So there could be several reasons why screening does not prolong someone’s life.
One type of cancer screening is a prostate-specific antigen (PSA) test, which is a blood test to screen for prostate cancer
For example, some studies have drawbacks, such as the risk of bowel perforation during a colonoscopy or a heart attack after prostate removal.
There’s also the risk that tests will give a false negative result and, with that, a false sense of security, the researchers said.
Dr. William Dahut, chief scientific director of the American Cancer Society, who was not involved in the study, told CNN that cancer studies were not designed to extend a person’s lifespan, but that their purpose was to reduce premature deaths from cancer.
Dahut explained, if a person’s life expectancy at birth is estimated to be 80 years old, then cancer screening can prevent someone from dying of cancer at age 65, but that doesn’t necessarily mean they live to be 90 years old instead of the estimated 80 years. .
“Nobody says, ‘If you do your cancer research, you’re going to live to be 100 years old.’ But we know that cancer is the second leading cause of death, the leading cause of death before age 85.”
Doctors in the US recommend certain tests for people of different ages or who have certain risk factors, such as a family history of cancer or certain lifestyle habits, such as smoking.
Long seen as a way to detect and diagnose cancer in its early stages, when it is easier to treat, a meta-analysis of more than a dozen clinical trials has cast some doubt on the effectiveness of six common screening procedures.
In the study Published Tuesday, researchers from the University of Oslo in Sweden analyzed 18 clinical trials that followed more than 2.1 million American cancer patients for more than a decade.
The meta-analysis assessed six different screenings in cancer patients who were and were not tested.
Observed tests include a mammogram for breast cancer, a colonoscopy, sigmoidoscopy and faecal occult blood (FOBT) testing for colorectal cancer, computed tomography (CT) screening for lung cancer in smokers and ex-smokers, and prostate-specific antigen (PSA) testing for prostate cancer . cancer.
The preventive testing researchers found the most life expectancy was a sigmoidoscopy, a screening test for colon cancer that examines the rectum, colon, and colon with a scope inserted into the anus.
Patients who had undergone this test had their life expectancy extended by 110 days.
In addition, the life expectancy of patients who received a screening test for lung cancer was extended by 107 days.
However, no significant extra days of life were found in patients who received a mammogram (zero days), a PSA test (37 days), a colonoscopy (37 days) or a FOBT (zero days).
Preventive procedures in the US are encouraged by much of the health care community and reimbursed by many health insurance companies. However, this study, along with previous evidence, suggests that more screenings do not equate to more lives saved at a population level.
Although these tests are promoted, little attention is paid to the possible disadvantages of the prevention measures.
The University of Oslo researchers noted that cancer screenings are not benign. While many people will undergo these tests without incident, for some they can actually cause health problems.
Tests observed in the study included a mammogram for breast cancer, a colonoscopy, sigmoidoscopy and fecal occult blood test (FOBT) for colorectal cancer, computed tomography (CT) screening for lung cancer in smokers and former smokers, and prostate-specific antigen (PSA) testing on prostate cancer
Too much testing can also lead to over diagnosis. Some people undergoing a cancer screening that discovers cancer may receive unnecessary and potentially harmful treatment to treat a slow-growing cancer that would not have harmed that person in their lifetime.
In addition, the more tests performed, the greater the chance of false positives. In addition to mental strain and anxiety, this can lead to extra expensive and unnecessary examinations.
But the researchers stressed: “We are not advocating that all screening should be stopped.”
Some tests may be worthwhile, but “institutions and policymakers that promote cancer screening tests for their life-saving effect may find other ways to encourage screening.”
They added that their estimates were also “uncertain,” adding large differences in life expectancy.
While the study found that a sigmoidoscopy was most likely to extend life by 110 days, the total period ranged from zero days to 274 days.
While screenings may not add years to a person’s life, they can detect cancer early enough to give that person a better chance of survival and a healthier life throughout their original lifespan.