Society of Nuclear Medicine 2009: Radioactive Patch Effectively Treats Skin Cancer
TORONTO, ONTARIO, June 22, 2009 — The application of a skin patch that delivers radiotherapy can be an effective alternative to surgery to treat skin cancer, according to data presented at the Society of Nuclear Medicine 56th Annual Meeting.
In a pilot study, investigators at the All India Institute of Medical Sciences in New Delhi looked at the effect of a phosphorus-32 skin patch to treat basal cell carcinoma. Findings were presented by Priyanka Gupta, BSc, PGDM, MSc, the study's principal investigator and a radiation technologist in the Department of Nuclear Medicine.
Ms Gupta described basal cell carcinoma as the least aggressive skin cancer, but she noted that, depending on the site of the lesion, it can be challenging for clinicians to remove the lesions surgically.
"Surgery can have some disadvantages, such as [when] it is difficult to operate at the site of the tumor or is in patients with tumors at multiple sites [making] grafting after a surgical operation [difficult]."
The downside of radiotherapy for patients is that it may require multiple visits to a clinic, and there may be a strong potential for damage to neighboring healthy tissue, said Ms Gupta.
A total of 8 patients (4 men and 4 women) participated in the study. They ranged in age from 45 to 74 years (mean age, 57.25 years). They had all been diagnosed with unifocal basal cell carcinoma on the face that was confirmed on histology. Of the 8 patients, 4 had lesions that were proximal to the eye, 3 had lesions on the nose, and 1 had a lesion on the forehead. No patients had lesions that spread to underlying structures.
The sealed patches, which delivered radioactive phosphorus-32 containing 1 mCi/cm2, were designed to fit the size and shape of the individual lesions. The patches were applied over the lesions for 3 hours. The patches were reapplied on day 4 or 5 and again on day 7 or 8 after the initial application; each application was for 3 hours.
"Since this is the first study of its kind, we chose patients who only had 1 [lesion]," Ms Gupta said in an interview with Medscape Radiology. Other exclusion criteria were age less than 18 years, a history of blood, renal, or liver disorders, and breastfeeding or pregnancy.
The patches were checked for any possible leakage prior to application, noted Ms Gupta.
Clinical examinations were done at various time points after the treatment to assess healing, and investigators performed biopsies 3 months after treatment.
In all cases, the examining dermatologists noted that there had been flattening of the lesions, Ms Gupta said during an oral presentation. The biopsies were negative for residual malignant disease in all cases.
The investigators conducted hematologic and biochemical examinations of patients periodically over 3 months. They observed no signs of toxicity in patients.
Ms Gupta pointed out that phosphorus is an appropriate choice for the patch because it does not release gamma radiation.
A larger patient sample is needed to determine if this management approach is comparable or superior to standard treatment of basal cell carcinoma, said Richard P. Baum, MD, PhD, Professor of Nuclear Medicine, Chair of the Clinic for Nuclear Medicine, and Head of the Center for Positron Emission Tomography at Zentralklinik in Bad Berka, Germany.
"The efficacy appears to be very good," said Dr Baum. "It is a small group of patients. To see if it is an alternative to surgery or radiotherapy, we need to conduct a comparative study with more patients." Dr Baum suggested a comparative study of outcomes with surgery, external-beam radiation, and radiation delivered by the phosphorus-32 skin patch.
Although the investigators found no toxicity in routine monitoring of patients, they need to go a step further to rule out any possible radiation absorption, added Dr Baum.
"It's unlikely that there was leakage [from the patch], but I would have been interested in looking at radioactivity levels in the blood just to be sure," said Dr Baum.
Source: Medscape Medical News
