Op-ed: Not all screening tests lead to early, better treatment

The following op-ed was published on April 23rd, 2009 in the USA Today.

As a primary care doctor, it’s heartening to hear President Obama call for “the largest investment ever in preventive care.” That means more people, for one, will be undergoing tests to screen for various forms of cancer. But this might be one of those cases where what sounds like common sense is actually more complicated. Are early screenings always in the patient’s best interest?

Despite all the advances in medical technology, no screening test is foolproof or can guide doctor and patient with certainty on proper treatment.

Although it is true that finding and treating cancer at an early stage will help in some cases “” such as Pap smears that reduce deaths from cervical cancer “” the data are less conclusive for the vast majority of other cancer screening.

Two notable studies

The New England Journal of Medicine recently published two studies looking at the effects of prostate cancer screening, with conflicting results. The first, sponsored by the National Institutes of Health, found that such screening did not decrease deaths. The second study showed that for every death prevented, 50 men would suffer from over-diagnosis, which can range from a prostate biopsy to removing the prostate entirely.

Almost one-third of those treated for prostate cancer suffer from significant side effects, including impotence and urinary incontinence. Taken together, the study found that the benefit was minimal, and far from definitive.

Gilbert Welch, professor of medicine at the Dartmouth Institute for Health Policy and Clinical Practice, says, “I place considerable value on not suffering the side effects of treatment” and “death is not the only outcome that matters.”

To put the problem in context: Only 3% of men die from prostate cancer; 97% will die from something else.

Similar issues influence breast cancer screening decisions. Although current recommendations call for routine mammograms after age 40, the effectiveness of such tests might be slight. A recent analysis by BMC Medical Informatics and Decision Making found the chances of a 40-year-old woman dying from breast cancer over the next 15 years were 0.48% if she did not receive a mammogram, and 0.38% if she had.

Not all tumors harmful

Mammograms detect a number of slow-growing tumors that will never be harmful. But because doctors cannot be sure of which cancers are dangerous, every woman with a suspicious finding is subjected to a biopsy or breast surgery. For every life saved from breast cancer, 10 more lives will be affected by the ensuing procedures.

I’m not saying that all women and men should start refusing these tests. Obviously, some lives have been saved from early screening. But for every inspiring story of a person cured from cancer made possible by early detection, there are untold stories of many more who suffer from the side effects of unnecessary invasive procedures stemming from false positive test results.

The uncertainty surrounding tests is true of other cancers, including lung, skin, ovarian, testicular and pancreatic, where little compelling evidence has shown that early screening is beneficial.

As much as we’d like to believe that early detection automatically leads to better care, that is not always the case. There cannot be a one-size-fits-all approach. Persuasive arguments can be made for and against screening, and the decision is a highly personal one. But patients must be better informed of the potential consequences either choice can bring.