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Background: Nevoid basal cell carcinoma syndrome (NBCC) is an autosomal dominant multisystem disorder. Persons with the NBCC gene have varied susceptibility to basal cell carcinoma (BCC) development., Objective: We examined the anatomic site-specific distribution of BCCs and the relation between sun exposure and numbers of BCCs in NBCC cases., Methods: A questionnaire asking about lifetime sun exposure, sun behavior habits, and number of BCCs was sent to 16 families with NBCC evaluated between 1985 and 1991. The results were compared with previously published data for the general population., Results: In the general population, 88% of all BCCs in women and 86% in men occurred on the face, head, neck, and arms versus 59% in women with NBCC and 65% in men with NBCC. Of BCCs in the general population 9% and 12% occurred on the trunk versus 38% and 32% of BCCs in NBCC cases, in women and men, respectively. We did not observe a strong relation between numbers of BCCs and history of lifetime sun exposure., Conclusion: The anatomic-site distribution of BCCs suggests that frequent sun exposure may not be essential for the development of BCCs in patients with NBCC. However, the observation that there are more tumors on sun-exposed areas suggests that exposure to the sun promotes the development of BCCs in patients with NBCC.

Adverse effects associated with the long-term low-dose regimens of retinoids used in cancer chemoprevention studies are not well described. In order to examine the clinical and laboratory adverse effects of 3 years of intervention with isotretinoin (10 mg/day) and to assess potential risk factors for developing these, we collected adverse effect data on patients participating in a randomized, placebo-controlled trial designed to evaluate the effectiveness of isotretinoin in preventing the subsequent occurrence of new basal cell carcinoma. Our results showed a significantly higher incidence of adverse mucocutaneous effects and serum triglyceride elevations in the isotretinoin group (P < 0.001). Associated risk factors included male gender, very fair skin, and elevated pretreatment triglyceride levels. The toxicity observed, although less severe and less frequent, was similar to that seen with higher doses and should be weighed with adverse skeletal effects when considering long-term treatment of patients with moderate cancer risk.

Background: High-dose isotretinoin has been reported to have a prophylactic effect on nonmelanoma skin cancer, although it is associated with significant toxicity., Purpose: To test the effectiveness of the long-term administration of low-dose isotretinoin in reducing the occurrence of basal cell carcinoma at a new site in patients with previously treated basal cell carcinomas and to measure the toxicity associated with this regimen, we conducted a clinical trial at eight cancer centers., Methods: Nine hundred and eighty-one patients with two or more previously confirmed basal cell carcinomas were randomly assigned to receive either 10 mg of isotretinoin or a placebo daily. Patients were followed for 36 months and monitored at 6-month intervals for skin cancer and toxic effects., Results: After 36 months of treatment, no statistically significant difference in either the cumulative percent of patients with an occurrence of basal cell carcinoma at a new site or the annual rate of basal cell carcinoma formation existed between patients receiving isotretinoin and those receiving the placebo. Elevated serum triglycerides, hyperostotic axial skeletal changes, and mucocutaneous reactions were more frequent in the group receiving isotretinoin than in the control group, and these differences were all statistically significant (P less than .001)., Conclusion: This low-dose regimen of isotretinoin not only is ineffective in reducing the occurrence of basal cell carcinoma at new sites in patients with two or more previously treated basal cell carcinomas but also is associated with significant adverse systemic effects., Implication: The toxicity associated with the long-term administration of isotretinoin, even at the low dose used in this trial, must be weighted in planning future prevention trials.

In several studies between 1962 and 1978, topical tretinoin was proved capable of producing complete regression of actinic keratosis and basal cell carcinoma. But because its efficacy is not comparable to that of other modalities, topical tretinoin is currently used only as an adjunct to topical 5-fluorouracil in the treatment of actinic keratosis. One recent report found topical tretinoin ineffective in the chemoprevention of actinic keratosis. Although the oral synthetic retinoids isotretinoin and etretinate have been used in the prevention and treatment of cutaneous malignancy, the potential exists for chronic toxicity from the prolonged systemic therapy that appears necessary for maintaining the chemopreventive effect. For this reason, it may be appropriate to study further the preventive as well as therapeutic effects of topical tretinoin and other retinoids for actinic keratosis and skin cancer. If they prove safe and effective, the use of topical retinoids in the prevention and treatment of cutaneous tumors may be the most significant clinical application of these drugs.

Two patients with multiple basal cell carcinomas, due either to the nevoid basal cell carcinoma syndrome (NBCCS) or arsenical insecticide exposure, were treated with oral isotretinoin for 7 or 8 years, respectively. Gradually decreasing dosage levels were employed. During the initial courses of therapy, high doses (2.0-3.0 mg/kg/day) were intended as chemotherapy. In these patients only 6 of 40 (15%) lesions underwent complete clinical regression. In subsequent courses aimed at chemoprevention, the dose was progressively reduced from 1.5 to 0.25 mg/kg/day. During therapy, no new lesions were observed in the patient with the arsenical exposure. The NBCCS patient developed 1 new lesion during therapy at 1.0 mg/kg/day, 1 new lesion at 0.5 mg/kg/day and 5 new lesions at 0.25 mg/kg/day. Treatment was discontinued and the patient with the arsenic exposure developed his first new tumor 17 months afterwards; in contrast, the NBCCS patient developed 29 tumors within 13 months. These findings suggest that long-term therapy with isotretinoin is needed for the continuation of the cancer chemopreventive effect. However, the need for continuous rather than intermittent maintenance therapy, and the determination of the optimal dose for this purpose may depend on the etiology of the multiple carcinomas and on the tolerability of the lowest effective dose by the individual patient. With these encouraging data, it now appears appropriate to expand this pilot study and perform larger trials to determine the usefulness of isotretinoin in the chemoprevention of basal cell carcinoma in patients with multiple tumors.

Twelve patients with multiple basal cell carcinomas resulting from varying causes were treated with high-dose oral isotretinoin (mean daily dosage: 3.1 mg/kg/day) for a mean of 8 months. Of the 270 tumors monitored in these patients, only 8% underwent complete clinical and histologic regression. All patients developed moderate to severe acute toxicities, leading five patients to withdraw from the study. Retinoid skeletal toxicity was identified in two patients who were examined after long-term therapy. Lower doses of isotretinoin (0.25 to 1.5 mg/kg/day) were ineffective for chemotherapy but demonstrated a chemopreventive effect in a subset of three patients who received these lower doses for 3 to 8 years. Two of these three patients have been observed after discontinuation of therapy. In one patient with a history of arsenic exposure, only one new tumor has appeared in a 27-month posttreatment observation period; in the other patient with the nevoid basal cell carcinoma syndrome, 29 new tumors have appeared within a 13-month period. This suggests that the need for long-term maintenance therapy with isotretinoin for chemoprevention of basal cell carcinoma may depend on the underlying cause of the skin cancers.

Although much recent work suggests that retinoids can prevent the development of epithelial cancers, their mechanism of action remains unknown. Since malignancy has been associated with alterations in gap junctions, desmosomes, microfilaments, and hemidesmosomes, the authors examined freeze-fracture replicas and thin sections of cell membranes of: (1) 11 basal cell cancers (BCC) treated twice daily for two weeks with topical 1.0% retinoid acid (RA); (2) 21 BCC treated for 2 to 17 weeks with oral 13-cis retinoic acid (CRA) (1.0-8.0 mg/kg/day); and (3) 17 BCC prior to retinoid treatment and/or after applications of vehicle alone. Both thin sections and replicas were examined and photographed in a single-blind fashion, and the density and size distribution of gap junctions and desmosomes were computed planimetrically. Topical RA treatment induced a two-fold increase in gap junction density (P less than 0.025) over controls. In contrast, RA produced a concurrent = 35% decrease in desmosome density. Systemic CRA did not significantly alter either gap junction or desmosome density or size. Finally, neither RA nor CRA treatment appeared to influence hemidesmosome or microfilament populations. Structural changes in both treatment groups did not correlate with either tumor regression or inflammation. Topical and systemic retinoids may exert their antineoplastic activity by different cellular mechanisms.

The radiographic findings in 25 patients with the nevoid basal cell carcinoma syndrome are presented. Cystlike lucencies of the phalanges, a previously unreported finding, were seen in 46% of the patients in whom hand films were obtained. Mandibular cysts, present in 42% of cases, and exuberant intracranial calcifications were also characteristic features. Brachymetacarpalia, and rib and spine anomalies were also associated with the syndrome but are less specific findings.

Three patients with multiple basal cell carcinomas, due either to excessive sunlight exposure, the nevoid basal cell carcinoma syndrome, or arsenical insecticide exposure, were treated with oral isotretinoin for 2 1/2 to 4 years. Although higher doses were used initially, approximately 1.5 mg/kg/day was used for long-term therapy in all three patients. Therapeutic effects on existing tumors varied between each patient, and only nine of sixty-five lesions underwent complete clinical regression. No tumors enlarged in two patients; a few tumors enlarged slightly in the third patient, particularly during the later courses of therapy when isotretinoin was given at lower dosage. No new lesions have been observed in any of these three patients. With these encouraging preliminary data, it now may be appropriate to perform larger trials for longer periods of time to determine the usefulness of isotretinoin in the chemoprevention of basal cell carcinoma in patients with multiple tumors.