04:17am Monday 11 December 2017

Total Skin Electron Radiation Used to Treat Rare Cancer

Madison, Wisconsin – When Keith Doering developed a rash on his knee, it was initially diagnosed as a type of psoriasis. He tried a variety of treatments, but his symptoms worsened.

As the rash spread, the 68-year-old Baraboo resident, became increasingly concerned. “It started going all over my body and my face,” Doering says. “It got so bad that I thought I was going to lose part of my nose.”

He was referred to Dr. Gary Wood, chair of the Department of Dermatology at the University of Wisconsin School of Medicine and Public Health. Dr. Wood made the diagnosis of folliculotropic mycosis fungoides, a rare and aggressive variant of mycosis fungoides, which is a form of cutaneous T-cell lymphoma. This disease is difficult to diagnose because the symptoms and skin biopsy findings are often similar to those of other skin conditions.

Mycosis fungoides often requires close collaboration among dermatology, radiation oncology and hematology/oncology for optimal disease control. Dr. Wood treated Doering with a progression of skin-directed and systemic therapies, including chemotherapy drug, methotrexate. When these therapies didn’t work, Doering received focal radiation therapy at University Hospital to treat lesions on his face. But as lesions appeared in other areas – too many to treat individually – Dr. Matt Witek, UW Health radiation oncologist, discussed the option of total skin electron radiation therapy.

Total skin electron radiation therapy is designed to do the same thing that localized radiation therapy does – damage DNA to destroy cancer cells – but over a much larger area. For patients with early-stage mycosis fungoides, this treatment can provide long-term, symptom-free survival. Patients like Doering, who are in the later stages of the disease, receive a smaller dose, which is more tolerable in the short term.

This treatment method requires highly dedicated radiation physics expertise and a large treatment room to accommodate the distance needed to scatter electrons over a broad area. The UW Health East Clinic affords an ideal venue for the delivery of total skin electron treatment, and thus UW radiation oncologist Dr. Greg Cooley was contacted to engage Doering.

“The technique is complicated, but standardized,” Dr. Cooley says. “We perform significant quality assurance up front, including multiple measurements to verify dose profiles at the specific distance treated. On each day of treatment, we measure the radiation being delivered as an additional check to the calculated dose. This serves to verify that each area is getting the prescribed dose.”

For this treatment, the patient stands in a large box that has a plastic shield to reduce the energy of the electrons, which ensures penetration of only 4 mm into the skin to minimize effects on bone marrow and other internal structures. The patient receives radiation in six different positions – three positions per day over two days – to ensure the prescribed dose reaches as much of the overall skin surface as possible. Brief follow-up sessions are required to “patch” areas the initial treatment does not reach, such as the soles of the feet.

Doering’s initial treatment consisted of 15 sessions over a three-week period. To reduce side effects, Dr. Cooley used ceramic intraocular shields to protect Doering’s eyes. Midway through treatment, fingernail and toenail shields can be added to prevent loss.

Three randomized prospective trials using this significantly lower dose have shown a response rate of more than 88 percent, and the treatment has been found to be safe and reliable, resulting in prolonged symptom-free survival time for many patients. The lower dose and reduced toxicity provides the opportunity to repeat the regimen if symptoms recur.

Doering noticed significant improvement in his symptoms two weeks after completing the treatment. After two months, most of his lesions were gone. Currently, his doctors are managing the disease with medication, and he can receive further radiation if needed.

“My skin is a lot better. I don’t have the big, scabby sores anymore, and that’s amazing,” Doering says. “I have radiation skin reactions, but they will go away. The doctors want to see those, because they show that the radiation is working.”

University of Wisconsin


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