Swimming and the risk of cutaneous melanoma.

Recreational exposure to the sun may not explain fully current trends in melanoma incidence. The hypothesis was examined whether carcinogens in water play a role in the development of cutaneous melanoma. In a case-control study, 128 melanoma patients and 168 patients with other types of malignancy completed a detailed questionnaire on aquatic leisure time activities. All relative risk estimates were adjusted for age, gender, educational level, pigmentation characteristics, and exposure to sun habits. Regular swimming during the summer months in swimming pools and in open waters such as rivers and seas before the age of 15 years, was associated with odds ratios of 2.20 (95% confidence interval (CI), 1.05-4.62) and 2.41 (95% CI, 1.04-5.58), respectively, compared with no swimming at all or swimming in relatively unpolluted waters, such as lakes and fens. Melanoma patients learned to swim at a younger age; compared with those who never learned to swim or who learned to swim after the age of 12 years, the odds ratio was 1.87 (95% CI, 0.91-3.78) for those who learned to swim at ages 9-12 years, and 2.22 (95% CI, 1.16-4.26) for those who learned to swim before 9 years of age. Compared with persons who had no swimming certificates, an odds ratio of 1.25 (95% CI, 0.71-2.23) was found for persons with one or two certificates, and an odds ratio of 2.96 (95% CI, 1.25-6.96) for persons with three or more certificates. The positive association between a history of swimming and melanoma risk suggests that carcinogenic agents in water, possibly chlorination by products, play a role in melanoma aetiology.

Effect of intermittent exposure to sunlight on melanoma risk among indoor workers and sun-sensitive individuals.

Intermittent exposure to sunlight is considered to be an important risk factor for melanoma, but the associations reported in most case-control studies are surprisingly weak. The aim of this study was to evaluate whether the incorporation of a subject's background exposure to the sun and pigmentation characteristics (which are assumed to influence a person's susceptibility to sunlight exposure) could produce stronger associations between sunlight exposure and the risk for melanoma. A population-based case-control study was performed in the mid-eastern part of the Netherlands. The study group comprised 141 patients with a histologically verified melanoma and 183 controls with other malignancies who were registered by the same cancer registry. Patients with a lentigo maligna melanoma or an acrolentiginous melanoma were excluded. Information was collected by interviews and physical examination. We categorized subjects as indoor or outdoor workers on the basis of occupational exposure to the sun. Pigmentation characteristics, which are known to be risk indicators for cutaneous melanoma, were summarized as one sun sensitivity score. We used this score to distinguish between sun-sensitive and sun-resistant persons. The odds ratios associated with sunbathing, vacations spent in sunny countries, and sunburns were higher among the indoor workers than among the outdoor workers. After stratification by the sun sensitivity score, the effect of sunbathing, participating in water sports (swimming excluded), vacations to sunny countries, and a history of sunburn was largest for the sun-sensitive persons. The data show a general trend toward higher relative risks among indoor workers and sun-sensitive individuals. The results of this study support the intermittent sunlight hypothesis.

Melanoma and occupation: results of a case-control study in The Netherlands.

Several studies have reported excesses of risk of melanoma in specific industries. Data from a case-control study in The Netherlands, including 140 cases with a cutaneous melanoma and 181 controls with other types of malignancy, were used to evaluate whether the reported associations with these specific industries could be reproduced. Adjustment for characteristics of pigmentation and exposure to sunlight was made. Increased risks of cutaneous melanoma were found for subjects who had ever worked in the electronics industry (odds ratio (OR) = 2.03, 95% confidence interval (95% CI) 0.63-6.62), in the metal industry (OR = 2.61, 95% CI 0.96-7.10), and in the transport and communication branch (OR = 1.92, 95% CI 0.84-4.35). These ORs were adjusted for age, sex, education, hair colour, tendency to burn, freckling, and exposure to sunlight. No increased risks were seen for workers in the chemical industry, the textile industry, and among health care workers. Analyses according to duration and latency of exposure did not give consistent results, but existing patterns may be obscured by the imprecision of the estimates.

Cell kinetics in skin disorders with disturbed keratinization.

A relatively simple immunohistochemical method was developed and used on cryostat sections. The monoclonal antibody Ki67 was used as marker for actively cycling cells and Pab601 for germinative cells. Counts were expressed as Ki67- or Pab601-positive cells/mm. In order to improve our understanding of the pathogenetic mechanisms in skin disorders with disturbed keratinization we have measured cell kinetic values in dyskeratosis follicularis, pemphigus benigna familiaris chronica, autosomal dominant ichthyosis vulgaris, X-linked recessive ichthyosis, atopic dermatitis and psoriasis and compared them with previous values derived with autoradiography using tritiated thymidine. The results showed that microscopical acanthosis is related to an increase of the germinative population, while the increased epidermal turnover is associated with increased numbers of cycling cells. The cell kinetic changes seem to be all secondary except in psoriasis where a dysregulation in the epidermal growth may cause the epidermal changes. This simple method allows quick evaluation of drug efficacy which might be useful in atopic dermatitis and psoriasis.

Methotrexate and trimethoprim-sulphamethoxazole--a potentially hazardous combination.

A 74-year-old woman had been treated with methotrexate over 2 years for rheumatoid arthritis. She was admitted to the hospital because of non-healing leg ulcers. After being treated with trimethoprim-sulphamethoxazole for a urinary-tract infection, she developed severe pancytopenia, followed by pneumonia and septic shock. The patient died shortly after. Concomitant treatment with methotrexate and sulphonamides should be strongly discouraged.