Best practices for treating severe sun damage
Treating severely sun-damaged patients’ individual lesions with cryotherapy alone is unlikely to lead to optimal outcomes. That’s because of a concept called field cancerization, which suggests that cancer does not arise as an isolated cellular phenomenon, but rather as an anaplastic tendency involving many cells simultaneously, according to Anokhi Jambusaria, M.D., M.S.C.E., staff dermatologist, Baylor Scott and White Health, Round Rock, Texas.
“In other words, some skin cancers are not happening as an isolated occurrence, but in a background of severely sun-damaged skin,” according to Dr. Jambusaria, who presented on the topic of extreme dermatoheliosis in July at the American Academy of Dermatology’s (AAD’s) Summer Meeting in Boston, Mass.
“The presence of field cancerization represents a high-risk population with subclinical invisible disease, multiple primary tumors and premalignant change. Oftentimes, they need multiple and repeated treatments, leading to significant morbidity. Treatment of patients with field cancerization, therefore, should involve targeting the entire area, not just the individual tumor.”
The main thing for dermatologists treating these patients to remember is that the goal of treatment is some type of field therapy, which not only treats what dermatologists see, but also subclinical disease. They should consider — even in the case of field disease — whether or not their treatment is penetrating deeply enough to treat the pathology, she says.
“Some patients develop such thick hyperkeratotic scale that application of topical 5 fluorouracil creams may not be getting to the targeted cell,” Dr. Jambusaria says.
Recently published reports suggest specific multimodal treatments effectively address field cancerization.
In a case series1 by Jambusaria-Pahlajani, et al, researchers described four transplant patients with field cancerization, who had failed topical chemotherapy and cryotherapy. The patients were treated with curettage of hyperkeratotic lesions, followed by topical 5 fluorouracil twice daily, followed by photodynamic therapy (PDT) with one hour incubation.
“All patients had excellent response rates, with total or near total clearing of their disease. This treatment was tolerated well by most patients and had a durable response [rate] of up to 18 months,” Dr. Jambusaria says.
In another study of 12 patients2 with numerous squamous cell carcinomas, cyclic photodynamic therapy administered every four to eight weeks for two years reduced SCC development by 95%, according to Dr. Jambusaria.
Chemowraps with 5 fluorouracil might also be a good treatment option for some patients, according to the dermatologist.
“Based on anecdotal experience, topical 5 fluorouracil applied to the legs yields less inflammation/irritation then when applied to the face,” she says. “These areas are also likely to have full thickness atypia in the form of SCCis and superficial invasive disease.”
Given these scenarios, dermatologists should consider using chemowraps with 5 fluorouracil. Hyperkeratotic lesions may be treated with curettage before applying the first chemowrap, according to Dr. Jambusaria.
“A liberal amount of 5 fluorouracil is applied to the area followed by [an] Unna boot. Application is typically on a Monday and the Unna boot is left on for five to seven days before removing. Patients are able to remove the Unna boot at home. If the plan is to keep the Unna boot on for the full seven days, patients are asked to remove the Unna boot the night before reapplication,” Dr. Jambusaria says.
“In my experience, I will leave the first Unna boot on for five days, and then have the patient come back to re-assess, given one case report where the patient developed exuberant ulceration from chemowraps leading to systemic 5 fluorouracil toxicity from absorption. If [the patient does] not have a significant reaction for the first two weeks, then I will have the patient leave [it] on for a full week, removing the Unna boot at home the night prior to coming back in,” she says.
Typically, these patients need three to four weeks of treatment to achieve moderate inflammation and minor superficial ulceration, which Dr. Jambusaria says is her treatment endpoint.