Cancer Screening

What are the dangers of false positives/negatives?

Screens that have clinical diagnostic relevance such as pap smears, mammography, PSA, and regular comprehensive physical exams have been shown, with excellent scientific evidence, to provide early warning for diseases that are curable when caught in early stage.

However, screening tests are not infallible, and there is a danger of false positive/false negative. As a result, a person may go through emotional anguish thinking that they have a malignancy, and will undergo a more invasive test such as a biopsy. On the other hand, a false negative will allow a cancer to go undetected, thus allowing a tumor to grow larger and possibly spread -- thus rendering the need for more intensive therapy.

Do the risks outweigh the potential benefits?

Most current screening techniques are relatively non-invasive and carry minimal risk to the patient.

If a woman started mammograms in her 20s, for example, and she had no risk factors to speak of, the accumulative risk of radiation would be more dangerous, but that's not what the recommendations say.

Even if an unnecessary biopsy is done, the benefits to them outweigh the risks. And technology has advanced to the point where most biopsies are minimally invasive and take only a few minutes to perform.

Some of the screening techniques, such as Pap smears, can pick up changes in cells before they even become cancerous. These results can alert a doctor to follow a patient more closely, or to remove the cells. Detecting potential cervical is far less intrusive and traumatic to the patient, than if full blown -- and possibly lethal disease -- developed.

In a perfect world, everyone would have access to these screens along with competent counseling to understand what the results mean and what they don't mean. When the screen introduces some risks of its own, such as the small amount of radiation inherent with radiographic procedures, we take steps to reduce that risk with adjunctive care.

What should a person base his/her decision on?

Women have been hearing many news reports about mammography lately, and many seem to contradict each other. What this means is that while mammography may not be as accurate as once thought, it is still the best tool we have for early detection of breast cancer.

The current American Cancer guidelines are very reasonable. You don't want to overdue the current recommendations, but as there currently outlined, they're reasonable.

Discussing all test options with your doctor, and weighing in your own personal risk factors, is the best way to make a decision about testing, he adds.

Screens with limited diagnostic, clinical relevance, such as genetic screening, must be approached with caution. These tests may only raise unwarranted fears with the patient for a disease they may never experience.

There are some persons who will benefit from genetic screening, but their numbers are definitely limited at this point in understanding of their implications, he adds. The decision for genetic testing should be made on an individual basis with providers who are sensitive to the risks and benefits of these tests.