Retrospective study characterizes time frame for AK progression

April 1, 2006

San Francisco ? The progression of actinic keratoses (AKs) into a squamous cell carcinoma (SCC) takes about two years, according to a study presented by Ellen S. Marmur, M.D., at the 64th Annual Meeting of the American Academy of Dermatology here in March.

Retrospective study

In order to investigate the kinetics of the progression of AKs to SCC, Dr. Marmur and colleagues conducted a retrospective electronic chart review of patients seen at Mount Sinai Medical Center, New York, who had a pathologically confirmed diagnosis of AK and a subsequent pathologically confirmed diagnosis of SCC at the same site.

"Patients often resist treatment of AKs due to the irritation and healing time from many current therapeutic modalities. While a more controlled, in vivo study is warranted to further examine the kinetics of AK progression, the findings from our investigation provide some meaningful information that clinicians can use in patient counseling. Patients told that AK progression occurs relatively quickly, within two years, may be more motivated to receive and comply with treatment. Thereby, the incidence of SCC may ultimately be decreased," Dr. Marmur tells Dermatology Times.

While previous research provided some information on AK progression to SCC, the time scale had not been characterized.

"Based on available data, we believe that about 10 percent of AKs develop into SCCs, and the mechanisms underlying the progression are also understood. However, how quickly the progression occurs is not known," Dr. Marmur observes.

Study subjects

The study identified patients (n=5,191) with a pathologic diagnosis of SCC made during a recent 18-month period in the dermatopathology database at Mount Sinai. Of the more than 5,000 charts reviewed, 68 had a prior biopsy-proven AK at the site of the subsequently biopsy-proven SCC.

Matching the location of the two lesions was based on the physician descriptions in the biopsy and the chart notes of the surgical site.

"This method of matching represents one of the limitations of this study, since certainly there is an opportunity for location errors and the AK and SCC diagnoses being made of two separate lesions. On the other hand, in daily practice a physician is more likely to biopsy the same site for a recurrent lesion," Dr. Marmur observes.

The vast majority of lesions in the study group were on the face (68 percent) and scalp (17 percent) versus on the extremities (10 percent) and trunk (3 percent), but there was a wide distribution of anatomic locations for the head lesions.

"The small numbers of lesions within each anatomic site is another limitation of our study, and so it is really not possible to comment on potential location-related differences in kinetics," Dr. Marmur says.

She also acknowledges that the results may be confounded by possible lag time between biopsy and diagnosis of SCC.