Understanding Cancer Pathology and Staging

February 19, 2019

How much cancer, what it looks like and where it is will guide diagnosis and treatment.

The Pathologist

FISH (left) uses fluorescent molecules to “paint” genes, allowing the pathologist to determine genetic mutations or how many copies of a particular gene are present in each cell. IHC (right) is a staining test that helps detect and classify cancer cells.

A number of things must be considered before a doctor can offer treatment options for cancer. The doctor must know how much cancer is in the patient’s body, where it is located, whether it has spread, and the specific type of cells that make up the tumor and how aggressive they are.In addition to conducting laboratory tests to diagnose diseases in general, pathologists also conduct specific tests on the cancer to determine a number of factors, including the type of cancer cells, the grade of the cancer, the size of the tumor, the extent the cancer has invaded the surrounding tissue and whether the cancer has spread to other locations in the body. This information, compiled in a pathology report, provides patients and their medical teams essential information to determine the best treatment.

The pathologist first looks at the tissue with the naked eye in a “gross examination.” Its appearance and characteristics, such as size, weight, color and texture, are then recorded.

If an entire tumor or lesion has been removed, it is microscopically measured from the edge of the malignancy to the edge of the resected tissue, which should include healthy tissue. If cancer cells are found at the edge, it is a positive margin, suggesting more cancer cells could remain in the body. This means more surgery or other treatments might be needed to try to remove or kill any remaining cancer cells. A negative or clean margin means there are no cancer cells found at the edge of the removed tissue.

Translating a Pathology Report

By law, patients are entitled to a copy of their pathology report, and most hospitals will provide a copy free of charge. It’s important to keep a record of the pathology report to have documentation of the diagnosis; this information will be helpful in researching the disease.

Below is a brief explanation of information found in a pathology report.

Demographics: information about the patient, such as the patient’s name, age, sex and date of procedure.

Specimen: The origin of the tissue sample.

Clinical history: The patient’s medical history, including how the cancer was found.

Clinical diagnosis: The diagnosis doctors were expecting before the patient’s tissue was tested.

Procedure: How the tissue sample was removed.

Gross description: Details of the tissue sample, including its size, weight and color.

Microscopic description: How the cancer cells look under a microscope, including tumor characteristics, such as grade, tumor margins and pathologic stage.

Special tests or markers: Results of tests that look for proteins, genes and how quickly the cells are growing. These findings are often contained in a separate report.

Summary: A pathologic diagnosis based on the information from the entire pathology report.

Once removed, the specimen is cut into thin slices by the pathologist to be used for further testing.

The pathologist examines the tissue under a conventional microscope, but other techniques are sometimes used to identify factors involved in the abnormal growth of cells, including FISH (fluorescence in situ hybridization), and IHC (immunohistochemistry) or other molecular tests. Many tumor characteristics identified by these tests can be important factors in choosing the right treatment.

As the technology to examine cells has become more advanced, pathology offers more extensive information about which treatments will be most effective.

Patients should ask their doctor about the cancer’s pathology to learn as much as possible about why a certain treatment is recommended and how it will work against the cancer.

Grading Systems

If the patient’s cancer is very rare or if the doctor thinks the pathologist’s diagnosis is inconsistent with the patient’s symptoms and other test results, a second opinion might be appropriate.The pathologist provides a number of evaluative elements that can help patients understand their tumor. The tumor’s grade describes how abnormal the cancer cells appear under the microscope.

Factors that go into deciding the grade vary, but usually include the size and shape of the cell’s nucleus, the proportion of cancer cells that are dividing and the patterns the cells form as they join. If many cells are dividing, it can be a sign that the cancer is more aggressive.

How Big Is the Tumor?

Cancer cells that look more like normal cells usually grow and multiply slowly and are described as being low grade, well differentiated or grade 1. Conversely, cancers that do not resemble normal tissues are called high grade, poorly differentiated or grade 3 or 4. The attributes are combined into an overall tumor grade that ranges from 1 to 4 depending on the cancer type.

Grading systems vary for different types of cancer. For example, the grading system for prostate cancer ranges from 2 to 10. Patients should ask their doctors what factors go into grading the tumor and the scale used.

Staging Systems

Regardless of the system used, lower numbers signify less aggressive cancers, whereas higher numbers indicate more rapid growth. Tumor grade is an important indicator of prognosis in some cancers, such as brain, breast and prostate, as well as lymphoma and soft-tissue sarcoma.The cancer will also be staged from 0 to 4 with 4 usually indicating the cancer is advanced. Cancer types might be staged differently, so patients should try to understand how their cancer is staged and how important this information is for their cancer type.

Staging for most cancers is based on the following:

  • Location and size of the primary tumor;
  • The number of tumors and whether the cancer has spread to nearby organs and tissues, including the lymph nodes; and
  • Whether the cancer has spread (metastasized) to distant organs or tissues.

Meet the Team

The pathologist is only one member of a patient’s care team; cancer treatment and care involve many people with a variety of knowledge and skills. The makeup of the team will be determined by which specialties are best for treating the patient’s type of cancer. Patients should remember that they are at the center of their team, and they have the final voice in making decisions and choices about what happens to them.

Patients might encounter these professionals:

  • Medical and radiation oncologists, radiologists, pathologists and surgeons;
  • Oncology nurses, nurse practitioners and physician assistants; and
  • Social workers, oncology clinical pharmacists, dietitians, occupational and physical therapists, clergy, psychologists and psychiatrists.

Each doctor is supported by a specialized team— staff members who play a major role in the patient’s care.

Patients should try to understand the role of each person on the team (or teams), so that they can take full advantage of the skills and personal attention available to them.

For some cancers, such as bone and soft-tissue sarcomas, the grade is taken into consideration when the cancer is staged. In addition to what is contained in the pathology report, information used for staging is gathered from physical examinations and imaging tests, such as X-rays, computed tomography (CT) scans, positive emission tomography (PET) and bone scans and magnetic resonance imaging (MRI) scans.

TNM staging uses three characteristics of the cancer. The T refers to the primary tumor (the place where the cancer began); the N refers to the level, if any, of lymph node involvement; and the M refers to the presence or absence of metastasis. The meaning of these letters and numbers might vary for different types of cancer; some cancers might not have N3 as a category, and in other cancers, the classifications might have subcategories, such as T3a or T3b. Patients should ask their doctors about the staging system for their cancer.

Overall Stage Groupings

Stage

Description

Stage 0

Carcinoma in situ (non-invasive)

Stage 1 to 3

More extensive disease indicated by higher numbers (could include larger tumor, cancer present in nearby lymph nodes and/or cancer present in organs next to the organ in which the cancer began)

Stage 4

Cancer has spread to a distant organ (metastasized)

Once these factors have been determined, an overall number is assigned. Patients who are treated and then experience a recurrence, might or might not have their cancer restaged. A restaged cancer often is indicated by inclusion of the letter “R.”Newer chromosome tests and the analysis of multiple genes at a time (known as gene profiling) could subclassify the cancer and help determine prognosis and individual treatment.

Stage and grade are not the only factors that influence a patient’s prognosis. The patient’s type of cancer, treatment received and general health are also important. But understanding the information signified by the cancer’s stage and grade can help patients and their health care team choose the best course of action.


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