https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2808648?guestAccessKey=517677e9-c937-4996-9c4a-f734f09de19e&utm_source=For_The_Media&utm_medium=referral&utm_campaign=ftm_links&utm_content=tfl&utm_term=082823
Our study quantifies whether use of 6 commonly used cancer screening tests is associated with length of life. One test (sigmoidoscopy) significantly prolonged life and longevity by 110 days, although the lower bound of the 95% CI extended to 0. Fecal 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.
In recent decades, organized cancer screening programs have been established in Europe, Canada, the Pacific Islands, and in many countries in Asia. In the US, cancer screening is offered by many institutions and encouraged and reimbursed by most health care payers. Several studies have investigated the association between screening and all-cause mortality.6,28 Few have translated their results to practical and easy-to-grasp estimates for health care professionals and individuals on how much cancer screening may increase life expectancy. Our study provides these estimates.
Even if we did not observe longer lives in general with 5 of the 6 screening tests, some individuals prolong their life due to these screening tests. Cancer is prevented or detected in an early stage, and the individuals survive screening and subsequent treatment without harms or complications. Without screening, these patients may have died of cancer because it would have been detected at a later, incurable stage. Thus, these patients experience a gain in lifetime.
However, other individuals experience a lifetime loss due to screening.35,36 This loss is caused by harms associated with screening or with treatment of screening-detected cancers, for example, due to colon perforation during colonoscopy or myocardial infarction following radical prostatectomy.37,38
For 5 of the 6 screening tests investigated herein, the findings suggest that most individuals will not have any gain in longevity. For those who have their longevity altered with screening, the cumulative loss for those who are harmed must be outweighed in duration by the cumulative gain experienced by those who benefit to show unchanged lifetime in individuals who undergo screening compared with those who do not (Figure 1).
The outcomes we observed are similar to those for aspirin use for primary prevention of cardiovascular disease and cancer (0.6 fewer deaths per 1000 person-years).39 While the cancer screening tests we studied are widely recommended, aspirin use is not recommended for primary prevention of cancer, and the lack of recommendation for aspirin has been explained with too-small effects and adverse events, such as bleeding.39 In contrast, bariatric surgery to prevent obesity-related disease and premature death in people with obesity has recently been shown to prolong life by as much as 3.0 years after 24 years of follow-up.40
Our study may provide easy-to-understand estimates for prolongation of life attributable to screening that may be used in shared decision-making with individuals who consider undergoing a screening test. Our estimates may also serve to prioritize public health initiatives in comparison with other preventive measures, such as obesity treatment or prevention of cardiovascular disease.28
The lack of increased longevity with screening may also occur due to competing causes of death. Many of the cancers we are screening for share risk factors with more prevalent causes of death, such as cardiovascular and metabolic diseases. A lack of a significant increase in longevity due to cancer screening may therefore be due to death from competing causes at the same time a patient would have died of cancer without screening. A mortality shift from cancer to other causes of death without increased length of life is thus plausible.
Due to the stigma and the psychological burden, a cancer diagnosis may also cause extra noncancer-specific deaths from suicide, cardiovascular disease, and accidents.41,42 Also, increased surveillance after cancer screening may increase the risk of other incidental disease, which would not have been detected without screening.4
Our study quantifies whether use of 6 commonly used cancer screening tests is associated with length of life. One test (sigmoidoscopy) significantly prolonged life and longevity by 110 days, although the lower bound of the 95% CI extended to 0. Fecal 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.
In recent decades, organized cancer screening programs have been established in Europe, Canada, the Pacific Islands, and in many countries in Asia. In the US, cancer screening is offered by many institutions and encouraged and reimbursed by most health care payers. Several studies have investigated the association between screening and all-cause mortality.6,28 Few have translated their results to practical and easy-to-grasp estimates for health care professionals and individuals on how much cancer screening may increase life expectancy. Our study provides these estimates.
Even if we did not observe longer lives in general with 5 of the 6 screening tests, some individuals prolong their life due to these screening tests. Cancer is prevented or detected in an early stage, and the individuals survive screening and subsequent treatment without harms or complications. Without screening, these patients may have died of cancer because it would have been detected at a later, incurable stage. Thus, these patients experience a gain in lifetime.
However, other individuals experience a lifetime loss due to screening.35,36 This loss is caused by harms associated with screening or with treatment of screening-detected cancers, for example, due to colon perforation during colonoscopy or myocardial infarction following radical prostatectomy.37,38
For 5 of the 6 screening tests investigated herein, the findings suggest that most individuals will not have any gain in longevity. For those who have their longevity altered with screening, the cumulative loss for those who are harmed must be outweighed in duration by the cumulative gain experienced by those who benefit to show unchanged lifetime in individuals who undergo screening compared with those who do not (Figure 1).
The outcomes we observed are similar to those for aspirin use for primary prevention of cardiovascular disease and cancer (0.6 fewer deaths per 1000 person-years).39 While the cancer screening tests we studied are widely recommended, aspirin use is not recommended for primary prevention of cancer, and the lack of recommendation for aspirin has been explained with too-small effects and adverse events, such as bleeding.39 In contrast, bariatric surgery to prevent obesity-related disease and premature death in people with obesity has recently been shown to prolong life by as much as 3.0 years after 24 years of follow-up.40
Our study may provide easy-to-understand estimates for prolongation of life attributable to screening that may be used in shared decision-making with individuals who consider undergoing a screening test. Our estimates may also serve to prioritize public health initiatives in comparison with other preventive measures, such as obesity treatment or prevention of cardiovascular disease.28
The lack of increased longevity with screening may also occur due to competing causes of death. Many of the cancers we are screening for share risk factors with more prevalent causes of death, such as cardiovascular and metabolic diseases. A lack of a significant increase in longevity due to cancer screening may therefore be due to death from competing causes at the same time a patient would have died of cancer without screening. A mortality shift from cancer to other causes of death without increased length of life is thus plausible.
Due to the stigma and the psychological burden, a cancer diagnosis may also cause extra noncancer-specific deaths from suicide, cardiovascular disease, and accidents.41,42 Also, increased surveillance after cancer screening may increase the risk of other incidental disease, which would not have been detected without screening.4
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