ORLANDO Topical 5% imiquimod is an effective treatment for squamous cell carcinoma in situ and should be considered as an option for this disease, Dr. Theodore Rosen reported at the annual meeting of the Florida Society of Dermatologic Surgeons.
Imiquimod (Aldara) is approved for the treatment of superficial basal cell carcinomas, and although it has been used for Bowen's disease, data are lacking on its efficacy for this use, said Dr. Rosen, who is professor of dermatology at Baylor College of Medicine in Houston.
A review of 49 of his patients with Bowen's disease who were compliant with their treatment showed that nearly 90% had a complete response at an average follow-up of 2 years. About one-third of the cleared cases were verified on biopsy.
Importantly, five patients who were believed to be compliant had no response whatsoever. This supports the premise that about 1% of the population will fail to respond to imiquimod, Dr. Rosen noted.
An alternative approach to treatment should be used in such patients, he said.
In general, though, the response rate with imiquimod is reasonable. Findings from the three best studies of this treatment suggest that the overall response rate is about 85%, which is enough to warrant its consideration by physicians, Dr. Rosen said.
In his study, patients ranged in age from 48 to 85 years, and 96% were male.
The lesion was located on the extremities in 30% of patients, on the face in 25%, on the trunk or neck in 18%, on the genitalia in 11%, on the scalp in 9%, on the ears in 5%, and on the lips in 2%, he reported.
Lesions on the genitalia had a significantly greater risk of progressing to invasive disease (10% vs. 3% for other areas), yet all of the genital lesions in this study cleared with imiquimod treatment, he noted (Dermatol. Surg. 2007;33:42731).
Patients were treated daily for 616 weeks (every other day for patients with genital lesions) until the target area was heavily crusted and eroded.
"I tend to push it a little bit," Dr. Rosen said of the therapy, adding that it is important to monitor patients.
There have been a few case reports of Bowen's disease ostensibly being cleared with imiquimod, only to have a subsequent invasive lesion develop, he noted.
Patients who undergo treatment with imiquimod for Bowen's disease are at high risk and "shouldn't be out of your grasp," Dr. Rosen said.
Although some cases of invasive squamous cell carcinoma have been treated with imiquimod and the overall treatment success rate appears to be about 70%, it is not his treatment of choice for invasive disease, as it is for Bowen's disease, he said.
Dr. Rosen disclosed that he has served on the speakers bureau for Graceway Pharmaceuticals, the maker of Aldara, and has received honoraria from the company.