By: Vivian Yuen

What is a lymph node? A lymph node is a gland that plays a major role in our lymphatic system, filtering the liquid containing white blood cells called lymphocytes (these lymphocytes act as immune cells). Cells such as dendritic cells (immune cells that present antigens, which are markers for foreign cells) travel to the lymph node to present antigens. Essentially, dendritic cells act as journalists who “take a ‘snapshot’ of what is happening on the ‘front lines’” (Sompayrac). With this “snapshot”, helper T cells can be activated and trigger B cells to produce antibodies (antibodies tag antigens for our immune system to attack!). In summary, lymph nodes are sites in the body that further activate the immune response against invaders, such as cancer cells.


Above is a diagram of a colon with visible lymph nodes. The colon is the long worm-like organ, and the lymph nodes are the oval-shaped glands. As we can see, the lymph nodes are an essential part of the colon.

 

Interestingly, lymph node counts are important for doctors to understand the development of cancer. A lymph node count is a process in which surgeons remove at least 12 lymph nodes (the current standard is to remove 12 lymph nodes). Examining the removed lymph nodes can help determine whether the tumor has metastasized (spread to other parts of the body from the origin of the tumor) and how far the tumor has spread. If the tumor has spread to lymph nodes, then the cancer has most likely progressed to stage 3 or stage 4 cancer. Using this information, doctors can determine whether chemotherapy is appropriate (chemotherapy can be effective in the later stages of cancer, due to its lack of specificity toward a particular region of the body). Immunotherapy may be appropriate, depending on how compromised the patient’s immune system is.

This diagram shows that lymph nodes may be removed, along with the tumor, in colorectal/rectal cancer cases, due to the proximity of these two.

Additionally, this surgical process has generally shown to increase remission rates for patients. Specifically, removing lymph nodes has increased survival rates for node-negative patients. Node-negative patients are patients whose lymph nodes have not yet been “infected” by tumor cells. Perhaps removing a certain number of lymph nodes prevents the cancer from spreading to the lymph nodes and truly inhibiting the activity of lymphocytes. The survival rates for node-positive patients (patients whose lymph nodes have been “infected” by tumor cells) tend to not be as high as the rates for node-negative patients, unless more lymph nodes are removed. It might seem to make more sense that removing lymph nodes will improve survival rates for patients with tumor cells that have spread to lymph nodes. However in these patients, the stage of cancer is advanced and the tumor has extensively metastasized. Even more so, their immune systems may be weak since the lymph node would not be able to play its role as a lymph (the liquid containing lymphocytes) filter and as the location of antigen presentation and immune cell activation.

Surgeons have been considering to increase the number of lymph nodes removed, since doing so may increase survival rates. Specifically in patients diagnosed with colon cancer, node-negative patients had a high survival rate of about 87% if more than 20 nodes were resected. Node-positive patients had to have almost double the amount of nodes removed in order to have a similar survival rate. In fact, researchers found that patients with more than 40 nodes resected had a survival rate of about 90%!

Nonetheless, it is important to keep in mind that lymph node removal may not be completely necessary. It is critical to discuss with your doctor before proceeding with this surgery, considering that there are some risks associated with lymph node removal. While removing lymph nodes may increase survival rates and is a standard procedure, this process can also weaken your immune system. In some cases, lymph node removal can result in lymphedema, a condition in which the lymphatic system does not function properly, leading to compromised health.

Overall, lymph node surgery has both benefits and risks. While it can serve as an indication of tumor progression and as a partial treatment, it can also compromise the immune system’s strength.

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