Routine Cancer screening can save lives. Not so very long ago, most cancers were in their deadliest, late stages by the time doctors could detect them. That’s still true of some kinds of cancer, but with others — such as breast cancer, colon cancer, cervical cancer, and prostate cancer — advances in cancer screening now make it possible to find many tumors in their earliest stages1.
Scientists have developed, and continue to develop, tests that can be used to screen a person for cancer. At the heart of the problem is our justifiable fear of cancer. The message has been drummed into us.
Many people think that the main purpose of these screening tests is to look for cancer in people who don’t have any signs of the disease, or to find cancer in an early, easily treatable stage. But the overall goals of cancer screening are to2:
- Lower the number of people who die from the disease, or eliminate deaths from cancer altogether
- Lower the number of people who develop the disease
Not all screening tests are beneficial
Although some cancer screening tests have proven benefits that can help achieve these goals, others do not. When talking about cancer screening, it’s important to understand that these tests can increase the apparent “cure rate” of a cancer without actually affecting how many people die from the disease or the risk of dying from the disease. That’s because sometimes cancer screening tests find cancer that isn’t causing a person harm and won’t cause a person harm in his or her lifetime.
One example is screening for prostate cancer. Because of the widespread increase in prostate cancer screening, the disease is being found in more men. However, many of these cancers do not pose a health threat. That’s one reason why the number of deaths from prostate cancer today is still similar to what it was in 1975, even though the number of men who have been diagnosed with the disease and “cured” has gone up dramatically.
Because cancer screening tests can detect some tumors that don’t need to be treated, improved cancer survival rates don’t always mean that a test benefits everyone. In fact, the risks of having a screening test could outweigh the advantages. The best way to tell if a screening test has actual benefits, including a decrease in cancer deaths, is through randomized controlled clinical trials (research studies in people).
Screening benefits and risks
Deciding whether to have a screening test is not always as straightforward as it may seem. Screening has potential risks and benefits that a person should talk about with his or her doctor, especially in the context of his or her personal and family medical history. The benefits include a potential decrease in the number of deaths from cancer2.
The risks include:
Overdiagnosis: Cancer screening tests may find slow-growing cancers that otherwise would not have been found or caused harm in a person’s lifetime. The result is that a person may receive potentially harmful, painful, stressful, and/or expensive treatment that the person didn’t need.
False positives: Sometimes a cancer screening test will suggest that a person has cancer when they do not.
Increased testing: Both overdiagnosis and false positives can lead to additional tests that a person may not need. These tests can be physically invasive, costly, and cause a person unnecessary stress and worry.
False reassurance: Sometimes a cancer screening test will suggest a person does not have cancer when they actually do. As a result, a person may not get needed treatment.
Screening test recommendations
Different organizations provide guidelines on cancer screening tests. Recommendations vary on which cancers people should have screening tests for, which screening tests should be used to screen for a particular cancer, and when and how often those tests should be done. It’s important for people to talk with their doctors to determine which tests are appropriate for their age and medical history2.
Screening for cancer has an understandable appeal. Although cancer screening can potentially lower cancer deaths and the distress of cancer, it is important to remember that a person must weigh the potential risks and benefits for each screening test with their doctor. Some screening tests may be more appropriate for those who have a personal or family history of cancer or an inherited cancer-related syndrome. The best way to find the value of cancer screening tests is through randomized clinical trials.
- The Risks of Cancer Screening. Accessed at http://www.webmd.com/cancer/features/cancer-screening-risks-and-benefits?page=2 on July 09,2015
Cancer.Net. Cancer screening. Accessed at http://www.cancer.net/navigating-cancer-care/prevention-and-healthy-living/cancer-screening on July 09,2015