Skin cancer: risk to individuals using the tumour promoter benzoyl peroxide for acne treatment

Risk factors for basal cell carcinoma

The aim of this study was to assess the risk factors for basal cell carcinoma (BCC). A case-control study, carried out in two towns in Yugoslavia, comprised 200 BCC cases and 399 controls. For statistical analysis, univariate and multivariate logistic regressions were used. The risk factors found for BCC were: freckling before the age 15, seven or more weeks per year spent at the seaside during holidays (lifetime average), outdoor work during summer-time, occupational exposure to organic and non-organic dissolvents and organophosphatic compounds, use of tar for cosmetic purposes, and previous BCC in personal history. Subjects who tended to burn and not to tan after sun exposure also showed a significantly higher risk for BCC. Brown eyes and history of acne had a protective effect. This study confirmed the role of both constitutional and environmental factors in the development of BCC.

A study of acne treatments as risk factors for skin cancer of the head and neck

A retrospective questionnaire was conducted as to the risk factors for facial skin cancer with emphasis on acne and past treatments for acne, in particular use of benzoyl peroxide preparations. The response rate was 90.9% for 964 cases and 79.9% for 3856 controls. There was no association between acne and the use of any acne medication for the risk of facial skin cancer. Cases of skin cancer were significantly more likely to have used phototherapy or sunbeds than the controls (P = 0.024), and more likely to have had radiotherapy prior to diagnosis (P = 0.001). The major risk factors as determined by generalized linear interactive modelling were family history of skin cancer (odds ratio 2.68; 95% confidence interval 2.15, 3.34), light skin (1.54; 1.25, 1.89), sunburning easily (1.43; 1.16, 1.76) and Irish, Scottish, Scandinavian or German mothers (1.33; 1.11, 1.59).

Toxicity and carcinogenicity of potassium bromate--a new renal carcinogen

Potassium bromate (KBrO3) is an oxidizing agent that has been used as a food additive, mainly in the bread-making process. Although adverse effects are not evident in animals fed bread-based diets made from flour treated with KBrO3, the agent is carcinogenic in rats and nephrotoxic in both man and experimental animals when given orally. It has been demonstrated that KBrO3 induces renal cell tumors, mesotheliomas of the peritoneum, and follicular cell tumors of the thyroid. In addition, experiments aimed at elucidating the mode of carcinogenic action have revealed that KBrO3 is a complete carcinogen, possessing both initiating and promoting activities for rat renal tumorigenesis. However, the potential seems to be weak in mice and hamsters. In contrast to its weak mutagenic activity in microbial assays, KBrO3 showed relatively strong potential inducing chromosome aberrations both in vitro and in vivo. Glutathione and cysteine degrade KBrO3 in vitro; in turn, the KBrO3 has inhibitory effects on inducing lipid peroxidation in the rat kidney. Active oxygen radicals generated from KBrO3 were implicated in its toxic and carcinogenic effects, especially because KBrO3 produced 8-hydroxydeoxyguanosine in the rat kidney. A wide range of data from applications of various analytical methods are now available for risk assessment purposes.

Risk factors for basal cell carcinoma

Completed questionnaires regarding suspected risk factors for basal cell carcinoma (BCC) were completed by 538 basal cell carcinoma patients and 738 age-, sex-, and location-matched controls in Saskatchewan. Significant risk factors were identified using chi2 analyses. Relative risks were subsequently computed. The following relative risks were identified: occupation of farming, 1.29; prominent freckles in childhood, 1.23; family history of skin cancer, 1.22; sunburn, 1.19; Irish, Scottish, Welsh mother, 1.19; light skin color, 1.18; red/blond hair color, 1.16; and working outdoors more than 3 hours/day in winter, 1.13: The average age of cases of BCC with a family history of skin cancer was significantly lower than cases of BCC with no family history of skin cancer (63.86 vs. 67.02 years, p = 0.018). No association was noted between BCC and psoriasis.

Long-term in vivo carcinogenicity tests of potassium bromate, sodium hypochlorite, and sodium chlorite conducted in Japan

Long-term in vivo carcinogenicity tests of potassium bromate (KBrO3), sodium hypochlorite (NaClO), and sodium chlorite (NaClO2) have been conducted in Japan from 1977 to 1985. In these investigations, groups of approximately 50 male and 50 female F344 rats or B6C3F1 mice were given solutions of the compounds as their drinking water ad libitum at two dose levels determined on the basis of preliminary 13-week tests. Control animals were given distilled water. The carcinogenic potential of KBrO3 was tested by administering doses of 500 or 250 ppm to rats for 110 weeks. Significantly elevated incidences of renal cell tumors in males and females and mesotheliomas of the peritoneum in males as compared to controls were observed. When female mice were given KBrO3 at doses of 1000 or 500 ppm for 78 weeks, no significant differences in tumor incidences between experimental and control groups were apparent. NaClO was administered to male and female rats, respectively, at doses of 1000 or 500 ppm and 2000 or 1000 ppm for 104 weeks. In mice, NaClO was given at doses of 1000 or 500 ppm to either sex for 103 weeks. The incidences of tumors in NaClO-treated and control animals of both sexes were not significantly different in both rat and mouse studies. NaClO2 was given to rats of both sexes at a dose of 600 or 300 ppm for 85 weeks. No statistically significant differences were observed in the incidences of tumor formation between NaClO2-treated and control groups of both sexes. NaClO2 was administered to mice at a concentration of 500 or 250 ppm for 85 weeks. In males, the combined incidences of hyperplastic nodules and hepatocellular carcinomas of the liver in a low-dose group, and adenomas and adenocarcinomas of the lung in a high-dose group, were marginally increased compared to controls (p less than 0.05). However, these incidences in treated males were within the range of values of historical control data in our program. We concluded that KBrO3 was carcinogenic in rats of both sexes. NaClO was not carcinogenic in either rats and or mice under the conditions of the present studies. Although NaClO2 was shown to be noncarcinogenic in rats, the results for mice were evaluated as inconclusive. Also the results of two-stage mouse skin carcinogenesis using KBrO3, NaClO, and NaClO2 are presented. The necessity for further testing of oxidant chemicals to determine potential carcinogenic and/or promoting effects is suggested in view of the recently proposed role of active oxygen species in carcinogenesis.