When a patient receives a breast cancer diagnosis, the pathology report contains many technical findings. One such finding is Lymphovascular Invasion (LVI), which describes an observation made when tumor tissue is examined under a microscope. LVI is not the cancer itself, but a detail about the tumor’s behavior that provides significant information to oncologists. This finding is a key factor used to determine the risk of the cancer spreading and helps guide treatment decisions.
Defining Lymphovascular Invasion
Lymphovascular Invasion occurs when cancer cells physically enter the small channels that transport fluid near the main tumor. The term LVI combines “lympho-” (referring to lymphatic vessels) and “vascular” (referring to small blood vessels, or capillaries). These vessels provide a potential escape route for malignant cells.
The entry of tumor cells into these vessels is considered a critical step in the process of metastasis, or cancer spread. LVI indicates that cancer cells have broken away from the main tumor mass and penetrated the walls of these channels. Once inside, the cells can travel through the body’s fluid pathways, providing a direct route to potentially reach regional lymph nodes or circulate throughout the body.
Detection and Reporting in Pathology
LVI is a microscopic finding that cannot be detected through imaging tests like mammograms or ultrasounds. This observation is made only after a tissue sample, typically from a biopsy or surgical specimen, is processed and stained. A pathologist, a doctor specializing in diagnosing disease by examining tissue samples, scrutinizes thin slices of the tumor under a high-powered microscope.
The pathologist looks for groups of tumor cells lodged within spaces lined by endothelial cells, which form the inner layer of blood and lymph vessels. Since distinguishing between lymphatics and small blood vessels can be challenging using standard staining, the finding is often grouped together as LVI. Pathology reports indicate LVI as “present” or “absent,” and sometimes note the severity using terms like “focal” (limited) or “extensive” (widespread). In difficult cases, special chemical stains (immunohistochemistry) may be used to specifically highlight vessel walls and confirm the presence of cancer cells.
LVI as a Prognostic Factor
The presence of LVI is considered a significant prognostic factor in breast cancer, meaning it helps predict the likely outcome and future behavior of the disease. A positive LVI finding is generally associated with a more aggressive tumor biology and a higher risk of recurrence, as the tumor cells have accessed the circulatory system.
The primary concern with LVI is its strong association with the spread of cancer cells to the axillary (underarm) lymph nodes. Even if the initial sentinel lymph node biopsy is negative, LVI indicates a higher probability of subsequent local or regional recurrence. LVI is also an independent risk factor for distant metastases (cancer spreading to organs far from the breast).
LVI is one piece of information that contributes to the overall risk assessment. Therefore, oncologists consider LVI alongside other established factors, including the tumor size, the tumor grade, the patient age, and the hormone receptor status. LVI’s influence on prognosis can be pronounced in certain molecular subtypes, such as Luminal B and Triple-Negative breast cancers. While the absence of LVI does not guarantee a low-risk outcome, its presence suggests a need for a cautious approach to treatment planning.
Impact on Systemic Treatment Decisions
A positive LVI finding often impacts the choice of adjuvant systemic therapy, which is treatment given after surgery to eliminate cancer cells that may have already traveled outside the breast. Systemic therapies, including chemotherapy, hormone therapy, and targeted therapy, treat the entire body.
The presence of LVI can shift a patient from a lower-risk category into an intermediate or high-risk category. For patients in a borderline risk group, LVI can be the determining factor that leads to a recommendation for chemotherapy. The rationale is that if cancer cells have entered the vessels, they may be circulating as micrometastases, making systemic treatment necessary to destroy them before they establish a new tumor. LVI serves as powerful evidence of the tumor’s systemic potential, thus supporting the use of intensive systemic treatments to improve long-term disease-free survival.