ORLANDO – Careful patient selection is key to treating nonmelanoma skin cancer patients with superficial radiation therapy, according to Dr. William I. Roth.
"If you pick the right patients for radiation therapy, you can get great results," Dr. Roth said. An elderly patient with a basal cell or squamous cell carcinoma on the face or leg can be a good candidate, for example, especially if there are other comorbidities that make that person less than ideal as a candidate for surgery.
Photos courtesy Dr. William I. Roth
An 87-year-old woman with infiltrative basal cell carcinoma that refused surgery, at the initiation of superficial radiation therapy.
The typical skin cancer patient at Dr. Roth’s practice in Boynton Beach, Fla., is between 75 and 80 years old, and many are very active and play golf or tennis several times a week. They prefer radiation therapy over surgery because it is less likely to limit their activities or impinge on their lifestyle, he said.
Reduced risk of bleeding and infection are other advantages of radiation therapy compared with surgery, Dr. Roth said at the annual meeting of the Florida Society of Dermatology and Dermatologic Surgery.
"Radiation therapy is not going to replace Mohs. [But] I think skin cancer practices need both," said Dr. Roth, a volunteer clinical professor in the department of dermatology at the University of Miami.
Photos courtesy Dr. William I. Roth
The same 87-year-old woman with infiltrative basal cell carcinoma, at four months post therapy.
Cure rates of up to 95% or more are possible with superficial radiation therapy. "Radiation oncologists in my area are advertising 98% cure rates," Dr. Roth said. "I do still send a lot of patients to radiation oncologists, but I think you get excellent results [within dermatology] as long as you pick the right patient. It’s a great therapy."
Referral is appropriate when a lesion is deep and significantly large, and its depth and width cannot be accurately determined, Dr. Roth said. Patients also should be referred to a specialist if there is any evidence of perineural involvement.
Patients should be advised that some immediate posttreatment hypopigmentation is possible and that it generally improves quickly. The treated area usually looks its worst at about 2 weeks post treatment, Dr. Roth said. Some patients experience late effects, even up to a decade post treatment.
"I always scallop my port in the lead shielding so that 10 years later when the person gets some hypopigmentation it’s not going to be sharply defined," he said.
Four weeks post therapy skin can still appear thick, said Dr. Roth. "I would not rush to rebiopsy these patients, especially on the legs where there is a low turnover."
Although some physicians avoid radiation treatment of basal cell or squamous cell carcinoma on the legs, Dr. Roth has found value to this approach. "The legs are not absolutely a piece of cake, but as you move [treatment] up from the middle of the leg it becomes easier and easier." He added that grafting can be a challenge on the legs and surgical sutures can sometime pull through the skin. "I’m happy to do surgery. But to be honest with you, radiation therapy on the legs generally is less of a hassle for the patient."
However, use caution when treating lesions directly over the anterior tibial surface, he advised. "You have to be more careful ... right over the bone." He encountered two patients treated in this area whose skin healed nicely but they still experienced some sensitivity in their tibia. Dr. Roth suggested less aggressive treatment near the anterior tibia because "bone absorbs radiation to a much greater degree than the skin."
Photos courtesy Dr. William I. Roth
A 78-year-old woman with large area of two well-differentiated squamous cell carcinomas, at the time of biopsy.
Dr. Roth gave an example of a patient with two well differentiated SCC lesions on her leg that he treated with radiation therapy. Twelve fractions of radiation were delivered with the SRT-100 (Sensus Healthcare, Boca Raton, Fla.). The patient ulcerated and had a fairly brisk response but did not report any pain. Follow-up was conducted at months 1,2 and 5. "From my standpoint, it was a remarkably good response."
Results with the SRT-100 are very reproducible, Dr. Roth said. Energy imparted across the port or opening in the metal shield is consistent. The device delivers a flat field of radiation with a fairly fast drop-off deeper into the skin. The depth of the nonmelanoma skin cancer lesion generally determines the setting, Dr. Roth said.