J. Corwin Vance

A clinical trial of beta carotene to prevent basal-cell and squamous-cell cancers of the skin

BACKGROUND Beta carotene has been associated with a decreased risk of human cancer in many studies employing dietary questionnaires or blood measurements, and it has had protective effects in some animal models of carcinogenesis. METHODS We tested the possible cancer-preventing effects of beta carotene by randomly assigning 1805 patients who had had a recent nonmelanoma skin cancer to receive either 50 mg of beta carotene or placebo per day and by conducting annual skin examinations to determine the occurrence of new nonmelanoma skin cancer. RESULTS Adherence to the prescribed treatment was good, and after one year the actively treated groups median plasma beta carotene level (3021 nmol per liter) was much higher than that of the control group (354 nmol per liter). After five years of follow-up, however, there was no difference between the groups in the rate of occurrence of the first new nonmelanoma skin cancer (relative rate, 1.05; 95 percent confidence interval, 0.91 to 1.22). In subgroup analyses, active treatment showed no efficacy either in the patients whose initial plasma beta carotene level was in the lowest quartile or in those who currently smoked. There was also no significant difference between treated and control groups in the mean number of new nonmelanoma skin cancers per patient-year. CONCLUSIONS In persons with a previous nonmelanoma skin cancer, treatment with beta carotene does not reduce the occurrence of new skin cancers over a five-year period of treatment and observation.

Intralesional interferon therapy for basal cell carcinoma

In a clinical trial of 172 patients at four medical centers, interferon alfa-2b (1.5 x 10(6) IU) or a placebo was injected directly into biopsy-proved noduloulcerative or superficial basal cell carcinomas three times weekly for 3 weeks, for a cumulative dose of 13.5 million IU. Efficacy of treatment was determined at 16 to 20 weeks by examination of biopsy specimens that demonstrated cure of lesions in 86% of interferon-treated patients and in only 29% of placebo-treated patients. During the treatment course and follow-up, an initial inflammatory response was observed at the treatment sites, followed by diminished erythema, improvement in overall appearance, and a decrease in size of lesions. Side effects of treatment, mainly flu-like symptoms, were usually mild and transient and occurred more commonly in the interferon-treated group. Only three patients, all in the interferon-treated group, discontinued therapy because of side effects. One year after initiation of therapy, 81% of interferon recipients and 20% of those given the placebo remained tumor free. Noduloulcerative and superficial lesions were equally responsive to treatment with interferon. For some patients with noduloulcerative or superficial basal cell carcinomas, intralesional interferon alfa-2b may be an alternative, effective treatment.

Salicylic acid in karaya gum patch as a treatment for verruca vulgaris

A clinical study was conducted to evaluate the efficacy of a new delivery system for administering salicylic acid for the treatment of verruca vulgaris. The study compared wart resolution among volunteers who used karaya gum patches. The cure rate was 69% for warts treated with patches containing salicylic acid, which was significantly higher (p less than 0.01) than for warts treated with control patches (35%).

The Skin Cancer Prevention Study: design of a clinical trial of beta-carotene among persons at high risk for nonmelanoma skin cancer.

We describe a randomized clinical trial of oral beta-carotene (50 mg/day) for preventing nonmelanoma skin cancer. It is a multicenter study conducted at sites in California, Minnesota, and New Hampshire. This report describes the design of the study, baseline characteristics of the 1805 randomized patients, changes in their plasma beta-carotene and retinol levels after 1 year of treatment, and plans for statistical analyses. Important features of this study are (1) a high proportion of potential subjects were found to be ineligible or chose not to enter the study, (2) the study agent is readily available over the counter and in common foods, and (3) nonmelanoma skin cancer is a relatively minor health concern for most patients. These considerations necessitated intensive efforts to encourage compliance with the study regimen. There are also some unusual statistical features of the study. One is that the study outcome is routinely assessed only at annual examinations, so the precise time of failure cannot be identified. Also, a secondary goal of the study is to determine whether beta-carotene decreases the average number of new skin cancers per patient per year, and there are no established statistical methods for analysis of data in this situation. Alternative approaches to the analysis are discussed.

Punctate keratoses of the palms and soles and keratotic pits of the palmar creases

Punctate keratoses of the palms and soles and keratotic pits of the palmar creases are frequently confused. A prospective study of 283 patients revealed a prevalence of 11% and 3%, respectively, in a metropolitan county hospital dermatology clinic. Punctate keratoses of the palms and soles and keratotic pits of the palmar creases are similar in size, number of lesions per palm, aggravation by trauma, and predominance in blacks and in men. These entities are different in appearance, distribution, age at onset, prevalence, symptoms, and prognosis. Punctate keratosis of the palms and soles and keratotic pits of the palmar creases should be considered independent entities. To help eliminate confusion, we propose that punctate keratoses refer only to the hyperkeratotic papules scattered diffusely in the palms and occasionally in the soles and that keratotic pits of the palmar creases refer only the hyperkeratotic, conical depressions confined to the palmar creases.