Understanding the Genomics and Genetics of Cancer

Your Pathology Report

Once a biopsy of a tumor is taken, the specimen is sent to the pathology department where it is carefully examined by a specially trained doctor called a pathologist, or by a specialist known as a genomic or molecular pathologist. After studying the specimen with and without a microscope, documenting its size, describing its location and appearance, and performing special testing, the pathologist prepares a document that provides all the information about the characteristics of your cancer. This is known as a pathology report.

Most cancer diagnoses are based on the careful examination of tissue obtained during a biopsy of a suspected tumor or of the entire tumor after definitive surgery (removal of the tumor with or without lymph nodes). The pathologist’s final diagnosis of your cancer is based on all the findings of the examination.

This important document helps guide your oncologist and other members of your treatment team as they plan the treatment most likely to be effective for your particular type of cancer and your unique characteristics.

Understanding the Results on Your Pathology Report

The format of a pathology report may look different at different facilities, but most include these general terms.

Patient information : Name, birth date and biopsy date.

Size : The length, width and weight of the tumor. This is sometimes referred to as the gross description. 

Prognosis (outlook) is generally better for smaller tumors. Size is a primary factor in staging.

Location : Where the tumor is found.

Histologic grade : A grade is based on how closely the tumor cells resemble normal cells. The more the cancer cells look like normal cells (lower grade), the better the prognosis.

Surgical margins : This indicates 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 : This shows the other structures affected by the tumor. This is a factor in staging and determining treatment.

Lymph node status : This indicates whether the cancer has spread to lymph nodes. This is important for staging and for determining how extensive the cancer is.

Genomic test results are also included in a pathology report. The results may be considered primary or secondary.

Primary results are directly related to explaining your symptoms or the reason for testing. This includes molecular testing, which tests the tumor sample for genomic mutations or genetic alterations. Types of molecular tests may include cytogenetics studies, flow cytometry and immunohistochemistry. You may also see results for microsatellite instability (MSI) testing, a relatively new test that may guide treatment options in a more personalized way, and tumor mutational burden (TMB), which assesses the number of genetic mutations in a tumor. Often, the report will include information about available clinical trials appropriate for the genetic alterations reported.

Secondary (or incidental) findings are medically meaningful but unrelated to the reason for testing. Secondary findings from molecular testing 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.

When to consider a second opinion

Identifying all of the characteristics of the tumor to diagnose cancer is challenging. If the pathologist cannot determine the histologic type for any reason - for example, if the cancer is poorly differentiated - a second opinion from a genomic or molecular pathologist who specializes in cancer and molecular testing may be required. In this case, the pathologist may send a sample of the tumor and prepared microscopic slides to another pathology center for a second opinion.

Sometimes you may choose to seek a second opinion on your own. For example, if your pathology report does not contain a definitive diagnosis, requesting an opinion from another pathologist with extensive expertise in interpreting pathologic findings related to your type and subtype of cancer is strongly encouraged. Or you may have a rare type of cancer that not all oncologists and pathologists are experienced in treating.

Along with determining a diagnosis, a second opinion can confirm the diagnosis or even suggest an alternative one. Some doctors may favor one treatment approach, while others might suggest a different combination of treatments. Doctors in each oncology specialty bring different training and perspectives to cancer treatment planning.

Do not feel awkward or embarrassed about seeking another opinion. You deserve to know about all your treatment options, including clinical trials that you might want to consider. Because the goal is for you to get the best care possible, your pathologist or your oncologist can help you locate another expert to assist.
If you choose to get a second opinion, notes about samples that have been sent for other tests to another expert or hospital will be included on your pathology report.