Here’s something to ponder: Chances are, you have never seen the doctor who is at the front lines of determining virtually all of the key decisions about your health care.

Your pathologist is the behind-the-scenes player who handles laboratory testing that drives nearly 80% of all medical diagnoses and treatments. But this doctor is hardly ever mentioned—much less someone you’re likely to meet.

How could that be? On TV shows like CSI, pathologists examine corpses and investigate suspicious deaths. In real life, their work is much more far-reaching. Pathologists are commonly recognized for their role in diagnosing cancer when a biopsy is performed. But these medical doctors also analyze laboratory tests—checking for everything from elevated cholesterol levels and infections to kidney disease and the cause of skin growths.

You can think of it this way—anything that is biopsied, scraped off, drawn from your veins, coughed up or excreted will pass under the microscope of a pathologist, who looks at physical specimens for signs of risk and disease.

INTEGRAL FOR CANCER CARE

If you’ve been diagnosed with cancer, your initial diagnosis and the subsequent treatment plans always start with a pathologist.

Example: Your doctor might suspect that you have breast cancer—based on a mammogram, physical findings (like a breast lump), symptoms, etc.—but the actual diagnosis will depend on what’s discovered from a tissue sample that’s examined in a laboratory.

The cancer diagnosis is just the beginning. The pathologist will use microscopic criteria to “grade” tumors according to their severity…identify hormone receptors (such as those for estrogen or progesterone) that predict how tumors are likely to behave…and determine what treatments are most likely to be effective.

Will you do better if you have surgery first, followed by radiation or chemotherapy? Or will your cancer respond more readily to preoperative chemotherapy and/or radiation? The treatments that your doctor ultimately chooses, including the order of treatments, are largely guided by pathology findings.

Recent development: “Liquid ­biopsy,” which is based on a blood draw rather than a tissue sample, is an emerging technology that is transforming not just cancer care but virtually every disease process. To ensure accuracy and precision, pathologists are often involved in the design, validation and oversight of these tests.

Smart idea: If you’re diagnosed with cancer or any other serious condition, ask to see the pathologist’s report. Pay particular attention to the “diagnosis” section to learn the pathologist’s conclusion and the “comments” section, which gives additional information on any subtleties of your case.

TRACKING DISEASE

Many diseases (such as diabetes) and risk factors (including elevated cholesterol) can be diagnosed only by laboratory findings. But about 20% of pathology tests are requested after a diagnosis to determine how well a treatment is working.

An oncologist, for example, might order additional biopsies and/or other tests to track a tumor’s response to radiation or chemotherapy…and still more tests to fine-tune the treatments by adding or subtracting drugs, changing doses, etc.

Another example: You’ll need laboratory tests to determine if (or how well) medication to treat thyroid disease is working. The same goes for drugs such as insulin, blood thinners and cholesterol-lowering statins.

AN IMPERFECT SCIENCE

Most pathologists will come to the same conclusions when they look at tissue samples—but not always. Doctors are only human. They have different opinions and biases…and they sometimes make mistakes.

Example: In a Johns Hopkins study published in Cancer, researchers reviewed biopsy slides from more than 6,000 patients and found that 86 patients were given wrong diagnoses that could have led to unnecessary or inappropriate treatments.

Research published in JAMA, looking at biopsies for breast cancer, found that 13% of cases of ductal carcinoma in situ (abnormal cells that are found within milk ducts) were not universally agreed upon by pathologists. This doesn’t always mean that the pathologists made mistakes—there’s disagreement among experts about how to diagnose this condition or interpret laboratory findings. But the study suggests that patients and doctors should view pathology reports with some healthy skepticism.

My advice: Don’t hesitate to get a second pathology opinion, particularly if you’re dealing with a rare disease…when the treatment for a disease (often the case with cancer) largely depends on pathology findings…or when a pathology report doesn’t completely line up with your doctor’s best judgment. Important: A second pathology opinion will not require an additional biopsy—another pathologist is simply asked to review the slides from the first tissue sample.

These second opinions might be covered by insurance, but not always. Check with your insurance company before making the decision. Also, don’t assume that you must use a pathologist who practices in your area for a second opinion. Biopsy slides can be shipped anywhere. Your doctor can often coordinate a second pathology opinion. Just be sure that the pathologist is board-certified and that the work is being performed in a laboratory credentialed by the College of American Pathologists.

MEET FACE-TO-FACE

Most patients never meet the pathologist(s) involved in their medical care, but they should. I urge patients to come forward with questions, particularly when they’re dealing with a rare or complicated disease…or when they have questions about the diagnosis that their primary doctor cannot fully answer.

Personal story: I received a call from a breast cancer patient who felt overwhelmed by information. I was familiar with her case because I had made the initial diagnosis. I explained what her diagnosis meant and what the biopsy showed (in terms that a layperson could understand). Just as important, I was able to give reassurance that her treatment plan was appropriate.

It’s not yet routine for patients to consult with pathologists. But where I work, breast cancer patients are always given the chance to meet with a pathologist, just as they meet with oncologists and other members of their care team. While this practice is not widespread, it is gaining acceptance throughout the medical community.

My advice: Ask whether your hospital offers the opportunity to meet the pathologist, how to schedule the meeting and whether there is any cost associated with the visit—most of the time there is not.

PATHOLOGISTS ALSO CAN DIAGNOSE DRUG ABUSE

More than 115 Americans die every day from opioid overdoses—not just from heroin and other illegal drugs but also from prescription painkillers such as fentanyl, according to recent statistics. Primary care doctors are the first-line responders in this crisis, but many aren’t sure how to interpret the tests that determine if patients are misusing their medications—or not taking them at all.

Example: A patient who is given oxycodone (a powerful narcotic) for chronic pain. The patient’s doctor might order a basic urine drug test to ensure that the drug is being used correctly, but the results are inconclusive. If the doctor suspects (but isn’t sure) that the patient is misusing drugs, he/she might call me for advice. In such a case, I may recommend that the doctor order a urine test that looks for metabolites of oxycodone. The test will show conclusively if a drug is being used correctly.