This article discusses the concept of Sentinel Lymph Node Biopsy(SLNB) and how SLNB reduces surgical morbidity after cancer surgery.
In cancer surgery, lymph nodes surrounding the cancer are removed for one of two reasons.
- To remove all cancer when it has obviously spread to the nodes (therapeutic node dissection for treatment), or
- To evaluate whether cancer has spread to the nodes or not (elective node dissection for assessment/staging)
Elective node dissection (END) is necessary is because there is no other pre-operative diagnostic test that predicts accurately enough whether the lymph nodes are involved with cancer or not.
Depending on the location of the nodes, END can be an extensive procedure, with potential long-term effects such as limb swelling, stiffness, and poor cosmetic outcome. If all the nodes following END are found to be negative for cancer, it means that an extensive procedure was done with no therapeutic benefit. At the same time, END cannot be omitted because of the risk of leaving behind cancer in the lymph nodes.
In order to overcome this problem, the concept of Sentinel Lymph Node Biopsy (SLNB) was proposed. In this procedure, during surgery, a dye is injected near the tumor and is traced to where it enters the first lymph node/nodes. This single node/few nodes are tested for the presence of cancer. In case they are negative for cancer, it means that all the other lymph nodes surrounding the cancer are also negative and therefore do not have to be removed.
In the 1990s, multiple trials proved the validity of this concept for breast cancer and melanoma (a type of skin cancer commonly seen in Caucasians). However, most studies relied on the use of expensive equipment which was not easily available (radioactive dyes and radioactivity detecting gamma cameras). Later on, other trials (including a few done by my team at St. John’s Medical College Hospital1,2) further validated that SLNB could also be done effectively using cheaper and more easily available techniques.
Since then SLNB has also been found to be useful in other cancers like oral cancer, uterine cancer, and genital cancers.3
Currently, expertise and equipment for SLNB are available in most centers that routinely perform cancer surgery, and SLNB has become a standard of care for suitable patients.
- Trial no. CTRI/2016/02/006592. Dr Suraj Manjunath “Standardization of Sentinel Lymphnode Biopsy Technique For Breast Cancer and route map for sentinel node detection” https://ctri.nic.in
- Ramu D; Manjunath Suraj; Shivakumar, K. Journal of Cancer Research & Therapeutics . 2017 Supplement, Vol. 13, pS41-S41. 1/4p.
- Shivakumar K, Vipin G, Suraj Manjunath, et al. Sentinel Lymph Node Biopsy in N0 Neck for Squamous Cell Carcinoma of Oral Cavity: a Prospective Study. Indian J Surg Oncol 7, 375–379 (2016). https://doi.org/10.1007/s13193-016-0560-y