What You Need to Know About Biomarker Testing

People with cancer rarely ask about molecular testing for biomarkers, but they need to be better informed about what these tests offer and what they don’t.

Right now, doctors might ask patients if they would like to have a particular biomarker test, “but such tests are not part of the standard of care,” says Sudhir Srivastava, chief of the cancer biomarker research group in the division of cancer prevention at the National Cancer Institute.

Moreover, tests for every cancer are not yet available. Those that are can provide vital information that might mean the difference between effective and ineffective treatments, or suggest how aggressive treatments must be to keep a cancer in check. Molecular testing for genetic errors also can assess an individual’s personal risk when certain cancers run in families.

Cancer tests that are available can provide vital information that might mean the difference between effective and ineffective treatments, or how aggressive treatments must be to keep a cancer in check.

Sometimes, though, such tests can result in overtreatment and even harm, Srivastava and two co-authors warned in a recent editorial in the British Medical Journal. As the “crude screening tools of the past” are replaced by increasingly sensitive tests, they wrote, slow-growing and even completely nonlethal lesions are being detected and overtreated. Examples of cancer screening tests that can be “misleading, of questionable value, or none at all,” include cancer antigen 125 (CA-125) and transvaginal ultrasound for ovarian cancer; prostate-specific antigen (PSA) screening for prostate cancer; and chest radiography for lung cancer, according to the authors.

[Read more on how biomarkers are changing cancer treatment]

So what should patients ask a doctor when faced with a cancer diagnosis or fearful about their personal cancer risk? A partial list of questions follows:

• Is there a molecular test for my particular cancer?

• Does the test require a biopsy of my tumor or can it detect molecular changes in the blood or other bodily fluids?

• Is this test approved for use in my case and covered by insurance?

• How will it help diagnose or treat my cancer?

• How reliable and accurate is this test? Does it pick up indolent cancers or nonlethal lesions that may never cause health problems?

• How will the results be used to make a treatment decision?

• How does carrying a specific genetic mutation increase my risk for cancer and by how much?