Cancer screening may not extend life: Study

Screening for cancer may not help to prolong life, according to new research that followed the health outcomes of more than two million patients for nearly a decade.
 
The University of Oslo study, published in JAMA Internal Medicine, found current evidence does not substantiate the conventional wisdom that cancer screening extends lifetime.
 
The only exception found was colorectal cancer screening with sigmoidoscopy.
 
Crucially, the researchers do not want screening abandoned, but warned that patients need to be better informed of the associated risks and possible negative outcomes of screening.
 
‘Harms can occur at testing, such as perforation and bleeding during colorectal cancer screening, and at downstream diagnostics and treatment, such as septicaemia due to transrectal biopsy in prostate cancer screening or complications from surgery, radiotherapy, and chemotherapy,’ the study found.
 
The randomised clinical trial saw the 2.1 million enrolled participants followed for at least nine years.
 
It studied six commonly used cancer screenings: mammography screening for breast cancer; colonoscopy, sigmoidoscopy, or faecal occult blood testing for colorectal cancer; computed tomography screening for lung cancer in smokers and former smokers; and prostate-specific antigen testing for prostate cancer.
 
Scientists then compared screened patients to those who had not undergone screening.
 
After checking in for almost a decade, the only screening test which resulted in significant lifetime gain was sigmoidoscopy, which extended life by 110 days. 
 
There was no significant difference in the other conditions.
 
‘Faecal testing and mammography screening did not appear to prolong life in the trials, while estimates for prostate cancer screening and lung cancer screening are uncertain,’ researchers concluded.
 
However, while the results will likely come as a shock to many in the general population, RACGP Specific Interests Cancer and Palliative Care Chair Associate Professor Joel Rhee told newsGP he is not surprised.
 
‘The major cancer screening programs in Australia … have a substantial body of research evidence behind them, [but] this is mainly in the form of disease-specific outcomes with little evidence for improvement in all-cause mortality,’ he said.
 
‘While these findings should not be ignored, we must keep in mind that Australian cancer screening programs have a solid foundation of evidence from both Australian and international sources that demonstrate their effectiveness in detecting cancers early and improving morbidity and disease-specific survival.’
 
According to the Australian Institute of Health and Welfare (AIHW), cancer screening began domestically in the 1960s with ad hoc cervical screening.
 
The Cervical Screening Program and the National Program for the Early Detection of Breast Cancer, now known as BreastScreen Australia, began in 1991, and the National Bowel Cancer Screening Program was introduced in 2006.
 
The Cancer Council actively promotes that ‘cancer screening saves lives. Screening is one of the most effective ways to detect early signs of cancer’.
 
But Associate Professor Rhee said one main concern with cancer screening programs today is overdiagnosis.
 
‘The problem stems from the fact that current programs rely mostly on age to determine who should be screened and how often,’ he said.
 
‘Fortunately, researchers such as Professor Jon Emery’s general practice research group at the University of Melbourne, have recognised this problem and are developing a personalised approach to cancer screening so that screening recommendations match the patient’s individual risk profile.
 
‘The recent advances in genetic testing and genomics also have the potential to identify lower-risk and higher-risk individuals, leading to a more targeted screening program.’
 
Despite their findings, the report’s authors said they are not advocating for all screening to be abandoned.
 
‘Screening tests with a positive benefit–harm balance measured in incidence and mortality of the target cancer compared with harms and burden may well be worthwhile,’ the study said.
 
‘However, organisations, institutions, and policymakers who promote cancer screening tests by their effect to save lives may find other ways of encouraging screening.
 
‘It might be wise to reconsider priorities and dispassionately inform interested people about the absolute benefits, harms, and burden of screening tests that they consider undertaking.’
 
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