Does the number of lymph nodes removed have prognostic value?

This study examined whether the number of lymph nodes removed in breast cancer patients predicts survival more accurately than standard staging.

Lymph nodes are small, bean-shaped organs that act as filters along the lymph fluid channels. As lymph fluid leaves the breast and eventually goes back into the bloodstream, the lymph nodes try to catch and trap cancer cells before they reach other parts of the body. Having cancer cells in the lymph nodes is known as positive lymph node status (PLN) and suggests an increased risk of the cancer spreading. Determining whether cancer has spread to loco-regional lymph nodes (lymph nodes nearby the initial tumor site) is a critical step in the initial staging of breast cancer patients. Recently, some studies have shown that lymph node ratio (LNR), defined as the ratio of armpit lymph nodes positive for cancer cells to the total lymph nodes removed, was a better indicator than PLN regarding the prognosis (survival prediction) of breast cancer patients and it should be considered as an alternative in the staging system.

Breast cancer patients with sone or two positive lymph nodes are often considered 'low risk', in whom the need for lymph node removal was recently questioned. This trial tested if the number of lymph nodes removed in this 'low risk' group predicted survival.

This study included 309,216 breast cancer patients diagnosed with tumors smaller than 5 cm and one to two PLN. The median (middle number in a data set) number of lymph nodes examined was 11. Patients were divided into three categories according to LNR (low, intermediate or high). 74.0% of patients were found to have low LNR (less than 0.2), 18% to have intermediate LNR (0.21–0.65), and 8% to have high LNR (over 0.65). Patients who had low LNR were found to have a longer survival (66.1 months) than those with intermediate or high LNR (61.1 months and 56.5 months, respectively). Therefore, the LNR allowed for better risk stratification and more accurate prognosis.

In summary, the number of lymph nodes removed affects the accuracy of prognosis even in breast cancer patients of low risk. 

If you are diagnosed with a small breast tumor, with 1-2 positive lymph nodes, ask your doctor about the process of axillary lymph node dissection.