Why Don't We Treat Melanoma with SRT?

Radiation therapists like me claim that "superficial radiation therapy for the treatment of non-melanoma skin cancers," but why just non-melanoma? What about a melanoma disqualifies it from receiving superficial radiation therapy as treatment?

Why don't we use radiation therapy for melanoma?

Skin cancer-treating machines that facilitate superficial radiation therapy are popping up in dermatology offices worldwide, and all of them are advertising the same thing: a non-surgical treatment for non-melanoma skin cancers. But why does superficial radiation therapy work for some skin cancers and not others? What makes a melanoma diagnosis different from that of basal cell or squamous cell carcinomas? More importantly, what makes it untreatable with SRT?

What are radiosensitive tumors?

Basal and squamous cell carcinomas, or non-melanoma skin cancers, are referred to as radiosensitive tumors. These cancer cells respond to radiation therapy treatments with regression, or in more satisfying terms, by being destroyed. These malignant cells divide rapidly, and while they are splitting, they are the most susceptible to lethal damage caused by radiation treatments. When these cells are hit with radiation, they cannot repair the injury to their DNA, resulting in the demise of the cancerous cell.

How it works

The treatments are repeated, and the remaining number of malignant cells decreases each time until they are all eliminated. It sounds like a lot of radiation, but it’s only too much for the flawed cells. The dose of radiation used to treat basal and squamous cell carcinomas is a manageable amount for your surrounding good cells. The healthy tissue can repair, and it then repopulates the site. The non-melanoma skin cancer cells die off the normal skin cells reclaim the area.

How melanoma is different

Melanoma does not go down so easily. Melanoma is referred to as a radioresistant type of cancer. Radioresistance means that radiation doesn’t destroy the cancerous cells or is not enough to be an effective therapy. The same damage does not occur when melanoma cells are hit with radiation as it does with basal or squamous cell carcinoma.  Unlike the non-melanoma types, melanomas have the capability to repair the injury caused by radiation. On top of mending the damage, melanomas divide and spread rapidly, giving them their aggressive reputation. SRT is not performed in a single treatment, and some treatment courses can take months to complete. The extended timeline for treatments allows those cells that have not been destroyed to divide and create new cells. It is fighting an uphill battle.

SRT isn't totally off the table

This is not to say that radiation is never used in the fight against melanoma. Radiation can be used on very early-stage melanomas if the patient cannot have the tumor surgically removed. Radiation can also be used after surgical excision of melanoma to help lessen the risk of recurrence. Certain types of radiation can also help treat melanoma once it has spread in the body; these treatments are specialized and usually are exceptionally high doses given in a short amount of time.

This all might change

There is still hope for a future of superficial radiation for the treatment of melanoma. Scientists in Australia, the country with the highest rate of melanoma in the world, are studying treatment plans that improve the effectiveness of radiation on melanomas. While still in their experimental phases, the case studies apply higher doses, radiosensitizing drugs, and even heat to help destroy these cells.

Surgery is usually your best bet, for now

The most standard and currently most victorious treatment for melanoma is the surgical removal of cancer. But remember, everyone’s skin cancer is different. Always talk to your doctor about your treatment options and find out the best treatment for you!

Has anyone undergone superficial radiation therapy as a part of treatment for their melanoma?