After undergoing surgery, surgeons will work closely with pathologists to determine the details of the cancer based on careful analysis of the tumor under a microscope.
3 Important Parts of Cancer Diagnosis
Type, Grade and Stage
- Type
There are many different types of cancers that arise in the various sites of the head and neck, and it is very important to determine the precise cancer type, which depends on the features of the tumor cells as they appear under the microscope. Furthermore, there may be different subtypes of the cancer within that type. This may be represented as “histological subtype” on a pathology report. These classifications are specific to a patient’s cancer and may affect their treatment and prognosis. - Grade
The grade of cancer depends on how differentiated the cancer cells appear, or how closely they resemble normal cells. The factors used to determine tumor grade can vary between different types of cancer. A pathologist will assign a grade to the cancer. - Stage
Cancer is staged by the size of the tumor (T) and how far it has spread within the body; for example, whether the malignancy has moved to regional lymph nodes (N), or to distant sites within the body (M), such as the lungs. This staging system is referred to as the TNM Classification of Malignant Tumors. Numerical staging varies depending on the cancer type, but stages will typically range from an early stage (I) to a more advanced stage (IV) with respect to the features mentioned above.
Methods
In this section we will help to clarify pathology reports, explain specific pathologic features common to head and neck cancer, and introduce techniques that pathologists may use to help analyze tumors.
Biopsy
A biopsy is a procedure done by a doctor to further evaluate a suspicious lesion and examine it more closely. A biopsy involves the removal of cells or a small portion of the lesion, which will then be sent for analysis under a microscope by either a cytologist (specialist in looking at cells or a cluster of cells) or pathologist (specialist in analyzing tissue specimens) to determine whether the lesion is benign or malignant.
There are several different kinds of biopsies. The type of the biopsy is chosen based on the location of the lesion. It is important to note that biopsies are not always definitive, and additional testing or imaging may need to be done to complete a diagnosis. Learn more by reading the biopsy page.
Frozen Section
Frozen section is a pathological method used to perform rapid analysis of a tumor specimen while the patient is still in the operating room. Frozen sections may take various forms depending on the type of information that the surgeon needs in a given clinical situation. A biopsy may be performed to confirm the nature of the tissue that is in question: whether it is benign or malignant; if malignant, then what type of malignancy does it represent. Surgeons will take small samples of the tumor during surgery and send them to the frozen section lab to be analyzed.
Pathologists will freeze the specimen, cut it into very thin slices, and stain the slices with various dyes so that the specimen may be effectively examined under a microscope. Overall, this process can be completed within minutes. This process is incredibly valuable because the quick analysis at the time of surgery provides surgeons with the information necessary to make real-time decisions regarding the severity of the cancer and the extent of surgery that needs to be performed.
Surgeons may also send a cancer specimen to the frozen section lab at the time of a cancer resection in order to determine if the tumor has been completely removed. Analysis of the margins (edges of the tumor) is an important process that is performed in order to give surgeons the necessary feedback as to whether additional tissue needs to be taken in order to ensure that the removal of the tumor is complete.
Permanent Section
Permanent section is the standard pathologic method for analyzing the tumor as well as all of the specimens removed during surgery. The process of permanent section pathology is more thorough and detailed than frozen section. This process usually takes 2 to 7 days to complete depending on the procedure performed. The final pathologic staging will be based off the permanent section pathology.
Pathology Reports: CAP Protocol
The College of American Pathologists (CAP) updates their classification protocol every two years. CAP protocols differ based on the type of cancer a patient may have. Here we will define the categories included in the most recent version of the CAP protocol for head and neck cancer.
Procedure
This describes the surgical procedure that was performed.
Tumor Site
This describes the location of the primary tumor.
Tumor Laterality
This describes the body side (left, right, midline) where the primary tumor was located.
Tumor Focality
This describes how many distinct primary tumors were found. Unifocal – one focus. Multifocal – more than one focus.
Tumor Size
This describes the dimensions of the primary tumor.
Histologic Type
This describes the type of cancer as well as any specific subtypes or variants.
Histologic Grade
This describes the appearance of the cancer cells. It is only reported on some cancers.
Tumor Extension
This describes surrounding structures that may have been invaded by the cancer.
Specimen Margins
This describes the status of the margins around the tumor. Surgeons will take ‘margins’ or additional tissue surrounding the primary tumor to ensure that all of the cancer has been removed.
Lymphovascular Invasion
This describes whether the cancer has spread to surrounding lymph nodes and blood vessels.
Perineural Invasion
This describes whether the cancer has spread to surrounding nerves.
Regional Lymph Nodes
This describes the number of lymph nodes positive for cancer, the number of lymph nodes examined for cancer, the side(s) of the neck that contained cancerous lymph nodes relative to the primary tumor, and the size of the largest focus of cancer within a lymph node. Additionally, this section describes the presence or absence of cancer spread outside the boundaries of the lymph node, known as extranodal extension (ENE) and the degree of that extension.
TNM Staging
pT
Primary tumor classification based on the size and extent of the main tumor.
pN
Regional lymph node classification based on the number and characteristics of positive lymph nodes.
pM
Distant metastasis based on whether additional sites within the body have been invaded by the cancer.
Additional Pathologic Findings
This describes any additional findings that the pathologist notes during the examination of tumor cells. These findings could contribute to prognosis and treatment plan.
Ancillary Studies
This describes any molecular or biomarker test results that have been reported.
Additional Pathologic Features
Worst Pattern of Invasion IV or V
For oral cavity squamous cell carcinoma, worst pattern of invasion (WPOI) is a CAP classification that describes the pattern of tumor cell dispersion (also referred to as “tumor satellites”) from the primary focus of the tumor. It is a method of defining the interface of the cancer with the surrounding normal tissue. This may be included in some pathologic reports.
Mitotic Activity
This is the measure of how fast cancer cells are dividing and growing.
Necrosis
Necrosis is a form of cell death caused by a lack of blood and oxygen to the tissue. It may be triggered by trauma, radiation or impaired blood flow.
Genetic Mutational Analysis & Role in Targeted Therapy
Genetic mutations (abnormalities in gene sequences) may be linked to certain types of cancers. A doctor may advise that the tumor undergo genetic mutational analysis if they suspect the possibility of genetic influence on a patient’s cancer type. The results of these tests can result in targeted therapies related to the unique cancer type. Any patient interested in genetic and molecular testing should ask their doctor about testing options. There are several companies that provide genetic and molecular testing services. Learn more about Genetic & Molecular Testing.
