Discoveries unfold in skin cancer research

New York - Skin cancer and its prevention are high on the agenda of dermatologists and cancer researchers worldwide. New research on genistein (a compound found in soya beans and soy foods), the use of high-resolution ultrasound during Mohs surgery for skin cancers, and the kinetics of skin lesions as they progress to skin cancers are all new points of interest in the battle against this disease, reports Ellen S. Marmur, M.D., chief, division of dermatologic surgery, Mount Sinai Medical Center. Dr. Marmur spoke on these topics at the 8th Annual Mount Sinai Winter Symposium, here.

Genistein belongs to the isoflavone class of flavonoids. Also classified as a phytoestrogen, this substance is a plant-derived non-steroidal compound that displays estrogen-like activity. Epidemiological and clinical studies show an inverse correlation between soy diets and human cancer mortality. Animal studies show that soy diets inhibit chemical- and radiation-induced cancers.

According to Dr. Marmur, "Genistein has been proven to have a high anti-carcinogenic activity, especially in fermented soy products (e.g., soy sauce), and new research by Dr. Huachen Wei shows it is effective against UV-induced skin cancer and aging."

Research

Genistein has been proven to reduce UVB-induced skin tumors and inhibit UVB-induced erythema in human skin. Human studies with genistein have shown thymidine dimer production protection, gross observation of MED protection, as well as PCNA (peripheral nuclear cellular antigen) tumor protein production.

"Research suggests that soy isoflavones benefit humans in four ways: as estrogens and anti-estrogens, as cancer enzyme inhibitors, as antioxidants, and as immune system enhancers or stimulants," Dr. Marmur says.

Genistein is available systemically for adults and is already is use by cancer and transplant patients. The topical form of genistein, which will be available soon, may help prevent erythema and the development of skin cancers.

HRUS

The Longport Episcan I-200, an HRUS (high resolution ultrasound), uses 20 MHz, 30 MHz or 50 MHz center frequency ultrasound probes. This makes it suitable for imaging the skin and superficial soft tissue up to a depth of approximately 2 cm at a very high resolution.

The investigator cites a sequentially enrolled 20-patient study with high-resolution ultrasound in Mohs surgery where HRUS measurements were conducted by two independent physicians, clinical measurements by a blinded third physician, and Mohs surgery according to clinical evaluation and comparison of HRUS and clinical judgment.

Dr. Marmur concludes, "HRUS can help in preventing second-stage procedures. Currently, 40 percent of Mohs surgery requires a second stage. This leads to added costs of time and fees for the patient. Fewer stages will also enable the surgeon to complete more surgeries in one day."

Dr. Marmur cites other applications of HRUS. The Mount Sinai Division of Dermatologic Surgery has several research studies under way using HRUS for cosmetic purposes, including a comparison study of echogenicity of a wide range of filler products, the use of HRUS to determine the depth of filler products, as well as using HRUS in training physicians to inject filler products at the appropriate depth.

AK fighting advances

The third update Dr. Marmur offered was the kinetics of the progression of actinic keratoses (AK) to squamous cell carcinoma (SCC).

"We know from prior mathematical studies that 5 percent to 10 percent of actinic keratoses will become squamous cell carcinoma. Which actinic keratoses will convert to squamous cell carcinoma is impossible to study at this point," Dr. Marmur says.

Deeming a human prospective study unethical to find out when those actinic keratoses will become squamous cell carcinomas, the investigator performed a human retrospective database study to estimate this time course of progression.

Dr. Marmur and her team examined the clinical histories of all patients diagnosed pathologically with SCC between Jan. 1, 2004, and June 30, 2005. The clinical histories were then examined for previous pathologically confirmed AKs at the subsequent site of the SCC. Lesion locations were matched using physician descriptions of the surgical site. Of the total patient population (n=5191), 68 patients were determined to have had a pathologically confirmed diagnosis of an AK at the same site as the subsequent pathologically confirmed SCC.