At Diagnosis: Understanding Pathology & Staging
How much cancer, what it looks like and where it is will guide diagnosis and treatment
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 severely abnormal they have become.
The Pathologist
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. This information, compiled in a pathology report, provides patients and their medical team essential information to determine the best treatment.
[Translating a Pathology Report]
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 mass to the edge of the specimen or "margin." If cancer cells are found at the edge, it is a "positive" margin, suggesting more cancer cells may remain in the body. A positive margin means more surgery may be needed to ensure removal of all the cancer. A "negative" or clean margin means there are no cancer cells found at the edge of the removed tissue.
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 there are many techniques that are sometimes used to identify factors involved in the abnormal growth of cells, including fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC). Many of the 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, the 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 to fight the cancer.
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.
Grading Systems
The pathologist provides a number of evaluative elements that can help patients understand their tumor. Tumor grade, or histologic 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.
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 doctor what factors go into grading the tumor and the scale used.
Regardless of the system used, lower numbers signify less aggressive cancers, while higher numbers indicate more rapid growth. Tumor grade is an important indicator of prognosis in some cancers, such as breast, prostate, brain, lymphoma and soft-tissue sarcoma.
Staging Systems
The cancer will also be staged from 0 to 4 with 4 usually indicating the cancer is advanced. Different cancers are staged differently, so patients should try to understand how their cancer is staged and how important it 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 and/or tissues.
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), positive emission tomography (PET) 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 may vary for different types of cancer; some cancers may not have N3 as a category, and in other cancers, the classifications may have subcategories, such as T3a or T3b. Patients should ask their doctor about the staging system for their cancer.
Once these factors have been determined, an overall number is assigned. Patients who are treated and then experience a recurrence may or may not have their cancer restaged. A restaged cancer often is indicated by inclusion of the letter "R."
Newer chromosome test and the analysis of multiple genes at a time (also known as gene profiling) may 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 healthcare team choose the best course of action.
