A breast cancer pathology report may contain the term “lymphovascular invasion,” or LVI. This is a microscopic finding where cancer cells are observed inside small blood vessels or lymphatic channels near the tumor. This article will explain what LVI is, how it is identified, and what it means for a prognosis and treatment plan.
What is Lymphovascular Invasion?
To understand lymphovascular invasion, it helps to break down the term. “Lympho” refers to the lymphatic system and “vascular” refers to blood vessels. Both systems are extensive circulatory networks that move fluids throughout the body. When cancer cells break away from a primary tumor, they can use these networks as pathways to travel to other parts of the body.
LVI means that individual cancer cells or small clusters have entered these nearby circulatory “highways.” To do this, the cells must breach the wall of a lymphatic channel or blood vessel. Once inside, these cells, called tumor emboli, can be transported by the flow of lymph or blood.
LVI should be distinguished from lymph node involvement. LVI describes cancer cells entering the vessel system, while positive lymph nodes mean the cells have traveled along these pathways and started to grow in a lymph node. LVI is a precursor step that may lead to lymph node metastasis and the spread of cancer to distant sites.
How LVI is Identified
Lymphovascular invasion cannot be detected through imaging tests like mammograms or MRIs. LVI is a microscopic finding identified by a pathologist, a physician who specializes in diagnosing diseases by studying tissues. The examination is performed on breast tissue removed during a biopsy or surgery after a lumpectomy or mastectomy.
To find LVI, the pathologist cuts preserved tumor tissue into extremely thin slices. These slices are placed on glass slides and treated with dyes, like hematoxylin and eosin (H&E), which stain different cell parts in distinct colors. This process makes the tumor cells and the walls of blood and lymphatic vessels visible under a microscope.
The pathologist then examines these slides, looking for tumor cells within a space lined by endothelial cells, which form the inner wall of a vessel. If it is difficult to distinguish a true vessel, a technique called immunohistochemistry (IHC) can be used. IHC uses special antibodies to mark proteins found only on the cells that line lymphatic or blood vessels.
If cancer cells are seen inside these stained structures, it confirms the presence of LVI. The finding is then recorded in the pathology report as either LVI “present” or “absent.”
The Role of LVI in Prognosis and Staging
The presence of lymphovascular invasion is a factor oncologists consider when determining a patient’s prognosis. LVI reveals information about the tumor’s biological behavior. Its presence increases the risk that cancer cells have escaped the breast, which could lead to a recurrence later, either locally or as distant metastases in other organs.
The presence of LVI is associated with a higher likelihood of both local recurrence and distant metastasis, affecting survival rates. This holds true even for patients whose lymph nodes are negative for cancer. LVI signals a more aggressive tumor biology and is often correlated with other adverse features like a larger tumor size and a higher histologic grade.
LVI is a prognostic marker, but it is not formally part of the primary TNM (Tumor, Node, Metastasis) staging system from the American Joint Committee on Cancer (AJCC). The TNM system focuses on tumor size (T), lymph node involvement (N), and distant metastasis (M). Oncologists use LVI status alongside the TNM stage to refine their risk assessment.
This provides a more complete picture of the cancer’s potential to spread. It is one of several factors, including hormone receptor status (ER/PR) and HER2 status, that help guide the overall management plan.
Treatment Considerations with LVI
The identification of LVI on a pathology report directly influences treatment recommendations. The goal is to eliminate any cancer cells that may have escaped the breast, reducing the risk of future recurrence. This often means recommending more comprehensive treatments than if LVI were absent.
The presence of LVI is a factor in the decision to recommend chemotherapy, especially for early-stage, node-negative breast cancer. An LVI-positive finding suggests a higher risk of micrometastatic disease, which are tiny, undetectable deposits of cancer cells. In these cases, an oncologist is more likely to recommend adjuvant chemotherapy to destroy these hidden cells.
Radiation therapy decisions can also be affected by LVI. Following a lumpectomy, radiation to the breast is standard practice. If LVI is present, it increases the concern that cancer cells have traveled to regional lymph nodes. This may lead the radiation oncologist to consider expanding the radiation field to include nodal basins, such as those in the axilla (armpit), as a precautionary measure.
The presence of LVI does not change the indication for endocrine (hormone) therapy or HER2-targeted therapy, as those are based on the tumor’s receptor status. However, it reinforces the importance of completing the full course of these systemic treatments.