In a bracing op-ed published yesterday in the British Medical Journal, researchers questioned the idea that cancer screening "saves lives" as many PSAs for these services promise. Cancer researcher Vinay Prasad and his colleagues warn that cancer screening has "never been shown" to affect general mortality rates, arguing that patients are being over-screened and often misdiagnosed.

The problem they highlight is a common one in the medical field: statistics on how cancer screening affects mortality rates have been widely misunderstood and misreported. Prasad and his colleagues explain that studies show cancer screening can lower mortality rates for people who already have specific diseases such as lung cancer, but the general mortality rate has remained unchanged since the advent of common tests for breast cancer, colon cancer, neuroblastoma, and prostate cancer. In other words, screening may be slightly improving mortality rates for people who have a disease, but screening is not improving mortality overall. As the researchers put it in their op-ed, people are "simply...trading one type of death for another." More simply: even if you're screened for cancer, your risk of dying every year remains the same.

This wouldn't be cause for concern if it weren't for the fact that cancer screening is expensive for both patients and the healthcare industry. On top of that, screening can itself cause health problems. False positives, which are common, can lead to extreme anxiety, unnecessary treatments, and even death.

This is particularly obvious when it comes to prostate screening, as the researchers explain:

For example, prostate specific antigen (PSA) testing yields numerous false positive results, which contribute to over one million prostate biopsies a year. Prostate biopsies are associated with serious harms, including admission to hospital and death. Moreover, men diagnosed with prostate cancer are more likely to have a heart attack or commit suicide in the year after diagnosis or to die of complications of treatment for cancers that may never have caused symptoms.

The group continues, noting another issue is that cancer screening gives patients a false picture of their health outcomes:

In one study 68 percent of women thought that mammography would lower their risk of getting breast cancer, 62 percent thought that screening at least halved the rate of breast cancer, and 75 percent thought that 10 years of screening would prevent 10 breast cancer deaths per 1000 women. Even the most optimistic estimates of screening do not approach these numbers.

What's the solution? In some countries like Switzerland, the national medical board has stopped recommending annual mammograms. In the US, the standard of care for cervical cancer screenings has gone from yearly tests to bi-annual or even longer. Prasad and his colleagues say cancer screenings can be helpful, but only when a patient's specific history seems to call for it. These tests shouldn't be given by default but instead only after a doctor has discussed the pros and cons with patients—making it clear that screening may not be an effective way to reduce risk.

Eliminating unnecessary cancer screening, according to the researchers, might free up money to do a serious statistical analysis of how cancer screening affects general mortality rate. Such an analysis would require millions of participants, but it would still be cheaper than administering millions of cancer screenings. The researchers also suggest that the medical community should focus on coming up with "novel prostate screening strategies" that are more accurate.

To be clear, the op-ed does not suggest that you should cancel all your cancer screening tests this year. Instead, it cautions people to be realistic about these screenings because they do not appear to reduce general mortality rates. Most importantly, patients should talk with their doctors about whether such tests are absolutely necessary instead of undergoing them out of an unfounded belief that they "save lives."

BMJ, 2015. DOI: 10.1136/bmj.h6080 (About DOIs).