American Melanoma Institute · 5 min read
Why full lymph node dissection is now uncommon after a positive sentinel node, when surgeons still do it, and how lymphedema is recognized, prevented, and treated.
Until 2017, a melanoma patient whose sentinel lymph node contained cancer was almost always sent for a second, bigger operation to remove every remaining node in that area. Then 2 clinical trials changed practice. Today most people in this situation keep their lymph nodes, and the full operation is reserved for a smaller group.
Lymph nodes are small bean-shaped filters clustered in the armpit, groin, and neck. A sentinel node biopsy removes only the first 1 to 3 nodes that drain the skin around the melanoma. A lymph node dissection removes all the nodes in the region along with the fat that holds them.
The operation takes place under general anesthesia. Most people go home with a plastic drain tube under the skin, which stays for 1 to 3 weeks.
Short-term problems include fluid pockets called seromas, wound infection, slow healing, and numbness of nearby skin. The main long-term risk is lymphedema, a lasting swelling of the arm or leg. The American Cancer Society names lymphedema and surgical pain as the main reasons doctors avoid this operation unless the need is clear.
The larger of the 2 was the MSLT-II trial (Faries and colleagues, New England Journal of Medicine, 2017). It enrolled more than 1,900 patients from many countries whose sentinel node held melanoma. Half had an immediate completion dissection. The other half kept their nodes and had regular ultrasound checks of the area, with dissection only if cancer appeared later.
At 3 years, melanoma-specific survival was 86% in both groups. Dissection did improve control of disease in that node region (92% compared with 77%). It also caused harm: lymphedema developed in 24.1% of the dissection group and 6.3% of the observation group.
A smaller German trial, DeCOG-SLT (Leiter and colleagues, Lancet Oncology, 2016), randomized 483 patients with a positive sentinel node and found the same pattern. Survival free of distant spread at 3 years was 77.0% with observation and 74.9% with dissection. The trial closed early and had less statistical power than planned, which the authors acknowledged.
After these results, guidelines shifted. For a positive sentinel node, watching the remaining nodes with physical exams and ultrasound is now the preferred path, usually paired with a discussion of drug therapy to lower the risk of recurrence.
Dissection remains standard when lymph nodes are clinically detectable, meaning a doctor can feel an enlarged node or a scan shows one, and a needle biopsy confirms melanoma.
Surgeons also operate when melanoma appears in the nodes during ultrasound surveillance.
For melanoma that can be felt in the nodes, the sequence of treatment is changing. Giving immunotherapy before the operation, called neoadjuvant therapy, lets the immune system learn to recognize the tumor while the tumor is still in place.
In the SWOG S1801 trial (Patel and colleagues, New England Journal of Medicine, 2023), which enrolled 313 patients, giving pembrolizumab both before and after surgery led to fewer recurrences than giving it only afterward. The NADINA trial (Blank and colleagues, New England Journal of Medicine, 2024) enrolled 423 patients and tested 2 doses of ipilimumab plus nivolumab before surgery. Estimated 12-month event-free survival was 83.7%, compared with 57.2% for surgery followed by nivolumab.
In NADINA, 59% of patients in the neoadjuvant group had little or no living tumor left in the removed nodes. Researchers are now testing whether strong responders can have a smaller operation. More data is needed before that becomes routine.
Lymph fluid drains from a limb through the nodes at its root. Remove the nodes and the fluid can back up. The National Cancer Institute notes that lymphedema can start soon after treatment or years later.
Early signs are subtle:
Report these promptly. Early lymphedema responds to treatment far better than long-standing swelling, in which the skin thickens and hardens. A red, hot, painful limb with fever suggests cellulitis, a skin infection that needs antibiotics the same day.
For decades patients were told never to lift anything heavy with the affected limb. Research, mostly in breast cancer survivors, overturned this. The National Cancer Institute's review states that early concerns about exercise causing harm have not been confirmed, and a randomized trial of supervised, slowly progressive weightlifting suggested it may help prevent lymphedema. Exercise works like a pump for lymph fluid.
Evidence is thin that blood draws, blood pressure cuffs, or air travel trigger lymphedema. Many teams still suggest using the other arm when that is easy, as a low-cost precaution. Better-supported measures are keeping a healthy weight, since obesity is a consistent risk factor, and protecting the skin from infection with gloves for gardening and prompt cleaning of cuts.
Treatment begins with a certified lymphedema therapist, usually a physical or occupational therapist. The standard program, complete decongestive therapy, combines a gentle massage technique called manual lymphatic drainage, multilayer short-stretch bandaging, exercise, and skin care. Once the swelling is down, a fitted compression sleeve or stocking worn every day keeps it down.
Surgery is an option at specialized centers when swelling persists. In lymphovenous bypass, a surgeon connects tiny lymph vessels to nearby veins under a microscope, and it works best in early disease. In vascularized lymph node transfer, nodes from elsewhere in the body are moved to the affected limb.
