Understanding the Genomics and Genetics of Cancer

Your Pathology Report

The pathology report is developed by a surgical pathologist who is specially trained and a critical member of the cancer management team. The surgical pathologist and members of the pathology team assist in defining the extent of the cancer, the tumor grade (low vs. high) and the potential for surgical removal of the tumor, as well as other histologic features of the tumor.

Although it is common for people diagnosed with cancer to have a pathology report, it is not typically shared with them. It is not a secret, and you can request a copy at any time. It is a behind-the-scenes document that helps guide your medical team as they diagnose and plan the treatment, which may include clinical trials, most likely to be effective for you.

Surgical biopsies obtain tissue or lymph nodes, and liquid biopsies use a sample of blood or other body fluid to characterize cancer cells contained in the blood or fluid and test for pieces of DNA that are released from tumor cells. Once a biopsy of a tumor is taken, the specimen is sent to be examined by a specially trained doctor called a surgical pathologist, or by a molecular or genomic pathologist.

The pathologist studies the specimen with and without a microscope, documents its size, describes its location and appearance, and performs special testing, such as molecular testing. Those tests may include cytogenetics studies, flow cytometry and immunohistochemistry. Testing for microsatellite instability (MSI) and tumor mutational burden (TMB) may be included. These tests assess the number of genetic mutations in a tumor. Specific molecular tests are used for certain biomarkers.

Your pathologist may review tests on cells that are present in bodily fluids, such as urine, cerebrospinal fluid (the fluid around the brain and spinal cord), sputum (mucus from the lungs), peritoneal (abdominal cavity) fluid, pleural (chest cavity) fluid, cervical/vaginal smears, and bone marrow.

The pathologist prepares the pathology report containing the primary results, which is a final diagnosis of your cancer. Secondary (or incidental) findings are medically meaningful but unrelated to the reason for testing, and may also be included in the report. Secondary findings may include genetic risks for future disease, carrier status (carrying a gene for, but not exhibiting, a condition) and findings related to differences in how you may process medications.

The format of a pathology report may be different for each facility but generally includes the following categories.

Clinical history: Contains a brief summary of essential clinical information provided to the surgical pathologist by the oncology team when submitting a specimen for analysis.

Gross description: Includes the color, weight and size of a tissue sample as seen by the naked eye. It may also include the shape of the tissue sample and any visible abnormalities. Also documented are the site(s) from where the tissue was taken, the number of samples taken and whether any lymph nodes were removed.

Microscopic description: Includes information about the appearance of the cells after they have been stained and viewed under the microscope. Staining helps identify different cells and tissues and provides important information about the pattern and shape of cells, the structure of the tissue, the type and number of cells seen in the tissue sample, how abnormal the cells look (also called the tumor grade), and whether there are notable cell features (such as their arrangement and behavior).

Histologic grade: Based on how closely the tumor cells resemble normal cells.

Surgical margins: Indicate whether cancer cells are found in the normal tissue around the edges of the tumor. If they are, additional treatment (surgery or radiation therapy, for example) may be needed.

Extent of invasion: Shows the other nearby structures affected by the tumor. This is a factor in staging and determining treatment.

Lymph node status: Indicates whether the cancer has spread and helps determine how extensive the cancer is.