Lymph node status shows whether or not lymph nodes are cancerous. A physical exam (also called a clinical exam) can give a first estimate of node status. Enlarged nodes can be a sign of cancer spread. However, a pathologic exam is the best way to assess lymph node status. In this procedure, a pathologist looks at the nodes removed during surgery with a microscope. The results of a pathologic exam are used most often in planning treatment.
The most common technique for a pathologic exam of the lymph nodes is H&E staining. More advanced techniques, such as immunohistochemistry (IHC), are sometimes used to look for cancer after a sentinel node biopsy. In IHC, antibodies are applied to the tissue sample. These antibodies target epithelial cells (cells that cover external and internal body surfaces). These cells are not normally found in the lymph node and may be a sign of cancer. IHC is a sensitve test, and can catch the presence of just a few cells. However, it is not known if a few cancer cells found in a lymph node by IHC affect prognosis as much as a positive lymph node found by H&E staining. Small clusters of cancer cells (0.2 mm or smaller) found by IHC are considered to be lymph node-negative if the nodes are found to be clear of cancer using the H&E technique [6].
At some centers, lymph nodes are tested with a technique called reverse transcription polymerase chain reaction (RT-PCR) to look for RNA of cancer cells. However, the clinical value of this test is unclear at this time.
Learn more about sentinel node biopsy.
Number of lymph nodes with cancer
One of the most important findings from a pathologic exam is the number of lymph nodes that have cancer (involved or positive nodes). The number of involved nodes guides treatment and predicts chances for long-term survival. In general, the fewer nodes with cancer, the better the prognosis [17].
Pathologic lymph node status
(To see the location of lymph nodes, see Figure 4.4)
pNX:
|
Axillary nodes cannot be assessed (for example, they were not removed during surgery)
|
pN0:
|
Lymph nodes do not have cancer (however, some small groups of cancer cells may still be found using sensitive tests, like immunohistochemistry)
|
pN1:
|
1–3 axillary nodes have cancer AND/OR
Internal mammary nodes have microscopic cancer found on sentinel node biopsy
|
pN2:
|
4–9 axillary nodes have cancer OR
Internal mammary nodes have cancer that is clinically apparent (for example, could be felt during a physical exam)
|
pN3:
|
10 or more axillary nodes have cancer OR
infraclavicular nodes (nodes below the clavicle) have cancer OR
Internal mammary nodes have clinically apparent cancer (for example, could be felt during a physical exam) along with one or more cancerous axillary nodes OR
Internal mammary nodes have microscopic cancer along with four or more cancerous axillary nodes OR
Supraclavicular nodes (nodes above the clavicle) have cancer
|
See Figure 4.7 for an expanded version of these tables that includes all subcategories.
Clinical lymph node status (only used when pathologic findings are not available)
(To see the location of specific lymph nodes, see Figure 4.4)
NX:
|
Nodes cannot be assessed (for example, they have been removed previously)
|
N0:
|
Axillary nodes do not have cancer
|
N1:
|
Axillary nodes have cancer, but can be moved around
|
N2:
|
Axillary nodes have cancer and are attached (matted) together or fixed to other structures, like the chest wall, OR
Internal mammary nodes have cancer without cancer in axillary nodes
|
N3:
|
Infraclavicular nodes (nodes below the clavicle) have cancer OR
Internal mammary nodes and axillary nodes have cancer OR
Supraclavicular nodes (nodes above the clavicle) have cancer
|
Updated 10/28/09
