How to read a pathology report

Or patients rarely see themselves as the doctor playing a critical role in a cancer patient’s journey, but the doctor’s mark is felt from diagnosis to treatment. A pathologist is a doctor who specializes in diagnosing disease by examining organs, tissues, cells, and body fluids. Their final product, a pathology report, maps the cancer, detailing vital data such as disease type, location, and disease stage, all of which help determine a patient’s treatment plan.

“If you don’t have a correct diagnosis, you can’t treat a patient properly.” — Fernando Yu García, MD, a pathologist at our Hospital in Philadelphia

How does this process work?

Several standardized procedures are performed before a diagnosis is made. After a patient’s tissue sample is collected during a biopsy or excision (surgical removal of tissue), the pathologist performs what is known as a panoramic examination, which is performed with the naked eye, not under a microscope. Observations noted on general examination include the appearance and characteristics of the specimen, such as size (usually documented in centimeters), texture (whether hard or soft, smooth or lumpy), and color. Gross examinations help establish an accurate diagnosis because some tumors have specific characteristics. The distance between the edges of the tumor sample and the remaining healthy tissue, called resection margins, is measured and documented. It is important to leave what are considered healthy margins during circumcision because it helps the surgeon determine whether all the cancer has been removed and whether the patient may benefit from further treatment.

The sample is then processed in a machine that dries the tissue and replaces it with paraffin wax, allowing thin tissues to be cut so that light can pass through. The pieces are placed on slides stained with tissue-discoloration dyes so that they are clearly visible under a microscope. Then the pathologist begins a microscopic evaluation. “You have to have a baseline for normal tissue,” says Bradford Tan, MD, chief of pathology and laboratory medicine at Cancer Treatment Centers of America. ^® (CTCA). Pathologists understand what normal life is like. We know what to look for and what to take note of. We look for the presence of a tumor and differentiate what we see compared to what normal tissue looks like.”

The divided samples are kept for future testing, which may be necessary if medical advances lead to the discovery of a new tumor marker or treatment, for example, or if the patient needs a duplicate slide for them to use for a second slide opinion. .

A pathologist should determine the type of tumor, which is roughly classified into “five cubes,” according to Dr. Tan. “A tumor that lines a surface, such as the skin or the gastrointestinal tract, is cancer,” he explains. If the tumor originates in soft tissues such as muscle, it is a sarcoma. If it comes from the neural crest (a group of specialized cells found throughout the body), it is melanoma, and if it comes from blood cells or bone marrow, it is in the leukemia and lymphoma group. The fifth cube could be a mixture of tumor types or of unknown origin.”

Why is the type of tumor important?

Determining the type of tumor is key because tumors behave differently. “Treatment of lymphoma will not work in the case of cancer,” Dr. Tan says. “And sarcomas usually don’t travel to the lymph nodes, but cancer does happen often, which is important. One type of cancer requires a lymph node dissection and another does not.” Tumors, such as breast and lung cancer, require additional testing because they may benefit from targeted therapies. Hormonal markers in breast tumors help identify which drugs may have the greatest effect, for example. “Typically a breast cancer patient with an estrogen receptor-positive tumor will receive tamoxifen, but a patient whose cancer is HER2-positive will receive trastuzumab (Herceptin®) ^. ), and if none of the slides show hormonal signs, the patient will usually receive chemotherapy,” says Dr. Tan. .

While all grading systems represent the degree of malignancy, in ascending order, Dr. Tan cautions that grading systems differ depending on the type of cancer. “The staging system for one cancer is not equivalent to the staging system for another cancer,” he says. For example, the Gleason staging system, which is widely used in prostate cancer, is different from the Nottingham staging system used for breast cancer.

Once the pathologist has examined all tissue samples with the naked eye and a microscope, graded them, and graded the cancer, assigning it a number from 0 (zero) to IV, stage 0 indicates that the cancer has not spread from its original site and stage IV, indicating progression the disease.

When reading the pathology report, Dr. Tan suggests paying close attention to the type, grade and stage of the tumor, and recommends getting a second opinion if you’ve been diagnosed with cancer. “It is always best to have a second pathologist review the diagnosis,” he says. You should make sure that the diagnosis is reviewed and confirmed before starting any treatment. We all trust our doctors. Trust but verify. Ninety-eight percent of the time, the diagnosis will be correct, but the difference in tumor type or grade may ultimately affect treatment.”