Cancer – To Screen or Not to Screen?

I once treated a patient who was in her 90s. She was less than 5 feet tall and had never weighed more than 90 pounds. But, she was tough as nails and had lived a great life. I came to advocate for her when the internist at the skilled nursing facility in which she lived insisted that she have a mammogram. She had already been diagnosed with breast cancer in her 70s, but was healthier than anyone else her age now. She knew that even if she did receive another diagnosis of breast cancer at this stage in her life, it would probably not be treated and it almost certainly would not shorten her life. She refused the mammogram, much to the dismay of the healthcare providers that treated her like a checklist of tests and screenings and medications. She lived to be well over 100 years old, without her mammogram.

Stories like this could be more likely if some cancer researchers have their way. An opinion piece in a recent issue of the Journal of the American Medical Association (JAMA) offers a new perspective on cancer screening. For decades, clinicians, researchers, advocacy groups, and public service announcements have touted the benefits of early cancer screening and insisted that women get routine screenings for breast and cervical cancer, and men get tested for prostate cancer, among other testing and prevention strategies. Still, while the nearly-30 years of research on early cancer screening and prevention has led to a vast body of scientific knowledge, it has not led to decreased deaths from cancer, calling in to question the effectiveness of cancer screening.

The authors of the JAMA article report that the incidence of breast and prostate cancers has increased since the initiation of aggressive screening and detection techniques. Also, the incidence of cancers early in life has increased. The authors contend that screening may increase the diagnosis of low-risk cancers, but still does not adequately diagnose aggressive cancers, explaining the lack of reduction in cancer mortality. The more aggressive the tumor, the less likely it is to be diagnosed in time to save the patient. Further, the authors believe that early screenings have led to over-diagnosis and over-treatment of cancers that would likely not harm an individual or shorten the lifespan.

Currently, nearly half of men at risk for prostate cancer receive routine PSA tests — the standard screening tool for prostate health, and 70 percent of women over 40 have had a mammogram recently. But, the increased prevalence of these screenings has doubled the likelihood that a man will be diagnosed with prostate cancer in his lifetime, and the chance that a woman will be diagnosed with breast cancer has risen from 1 in 12 to 1 in 8 in the last 30 years. Today, more than 800 women need to be screened in 6 years to prevent 1 breast cancer death.

Many studies support the conclusions in JAMA and report that early screening and cancer prevention practices have shown only modest improvements long-term survival over the last 30 years. Mostly, there is still a lot about cancer that remains a mystery. Tumors are all different and therapies are always evolving. Still, strides have been made — through drug therapy intervention, early detection tests, and healthy lifestyle education — in preventing or detecting early the 4 deadliest cancers in the United States (breast, prostate, lung, and colorectal cancer). Some clinicians support increased lifestyle and basic nutrition education instead of, or in addition to, traditional medical approaches for cancer screening and prevention. Still others support reforming the clinical trial system to allow earlier human trials and speed the development of new cancer treatments.

There are inherent limitations to screenings: Who should be a candidate? What should the patient do with the information? What is the success rate of the test? No one is advocating stopping the early detection and prevention strategies for cancer completely — they have saved countless lives. But, patients should be informed before undergoing the testing and the physicians should be able to separate the life-threatening cancers from the not-so-serious ones. Fine-tuning screening techniques and evaluating the patient’s stage in life and overall health are important before proceeding with mass cancer screenings for everyone. But, then again, if you or your family member were the 1 cancer death prevented by early detection, would you want everyone to be screened?

References

Esserman, L., Shieh, Y., & Thompson, I. (2009). Rethinking Screening for Breast Cancer and Prostate Cancer JAMA: The Journal of the American Medical Association, 302 (15), 1685-1692 DOI: 10.1001/jama.2009.1498

Greenwald P (2007). A favorable view: progress in cancer prevention and screening. Recent results in cancer research. Fortschritte der Krebsforschung. Progres dans les recherches sur le cancer, 174, 3-17 PMID: 17302181

GREENWALD, P. (2008). S1. Do we make optimal use of the potential of cancer prevention? European Journal of Cancer Supplements, 6 (3), 1-1 DOI: 10.1016/S1359-6349(08)70193-9