Dear OncoLink "Ask The Experts,"
My question is in regards to a periurethral melanoma. Do you know of any surgeries done for this problem using CyberKnife®?
Suzanne M. McGettigan, MSN, CRNP, AOCN, Board Certified Adult Nurse Practitioner and a Certified Oncology Advanced Practice Nurse, responds:
Periurethral melanoma sounds like it would be classified as a mucosal melanoma. These melanomas are separate from traditional cutaneous (skin) melanomas. Mucosal melanomas are sometimes called "hidden melanomas" because they occur in places that are not exposed to sun, which is the typical cause of cutaneous melanomas. They can occur in the nail bed, scalp, eye, or mucosal tissue (lining of the nose, mouth, female genitals, anus urinary tract, and esophagus). Mucosal melanomas are quite rare, but are treatable when found early.
Cyberknife is a method of performing what is called "stereotactic radiosurgery", or SRS, which is the careful administration of high-dose radiation therapy to a relatively small area of tumor. It is actually not surgery at all, but is contains this word because it is very precise and localized, like traditional surgery. This radiation can be administered by a conventional radiation therapy machine (called a linear accelerator) or a specialized machine (called Gamma Knife®, XKnife™, or CyberKnife® ). SRS delivers several hundred beams of radiation from many directions, forming a concentration of radiation at the one point where all the beams meet. This allows for a large dose of radiation to be delivered to the tumor, while sparing the surrounding tissue from the damage of the high dose. It is used to treat tumors that are not amenable to traditional surgical intervention, commonly those of the spine and central nervous system. These devices are located at centers across the country under physicians specially trained in their use.
In general, melanoma cells are not usually very sensitive to radiation, so this may not be the best treatment option. Surgical removal of the lesion is considered the gold standard, when possible.
Kuo, John S.; Yu, Cheng; Petrovich, Zbigniew ; Apuzzo, Michael L.J. The CyberKnife Stereotactic Radiosurgery System: Description, Installation, and an Initial Evaluation of Use and Functionality. Neurosurgery, Volume 53(5), November 2003, pp 1235-1239.