J. English

Benign melanocytic naevi as a risk factor for malignant melanoma.

Examination of 180 patients with cutaneous malignant melanoma and 197 control patients in a case-control study showed that the risk of melanoma is strongly related to numbers of benign melanocytic naevi (moles). Some unusual features of naevi--a diameter exceeding 7 mm, colour variation, and irregular lateral outline--also showed a strong association with the risk of melanoma, but the relation of numbers of naevi to risk was present even in the group of patients whose naevi had none of these unusual features. Biopsy of clinically atypical naevi from several of the patients at highest risk generally did not show dysplastic histology. Thus a group of people at high risk of melanoma may be identified by using simple clinical assessment of naevi.

The number and distribution of benign pigmented moles (melanocytic naevi) in a healthy British population

Total body mole counts have been performed on 432 normal healthy Caucasian subjects aged 4 days to 96 years (204 males and 228 females). The mean total body mole count in the first decade of life is three for females and two for males, rising rapidly in the second decade to a mean of 23 for females and 18 for males. In the third decade numbers are highest, with a mean of 33 for females and 22 for males. Thereafter, numbers of moles slowly drop until in the eighth decade they have fallen to levels similar to those seen in pre‐pubertal children. There is a significant association between the presence of naevi in early childhood (prior to 5 years of age) and the development in later life of large numbers of moles. In women there is no significant association between total mole counts and either parity or use of the oral contraceptive.

Fluorescent lights, ultraviolet lamps, and risk of cutaneous melanoma.

Exposure to solar radiation is increasingly being associated with a risk of cutaneous melanoma, and some risk has also been attributed to exposure to fluorescent lights. The risk of cutaneous melanoma associated with exposure to some sources of artificial ultraviolet radiation was examined in a case-control study in a Scottish population with fairly low exposure to natural ultraviolet radiation. The risk was not significantly or consistently raised for exposure to fluorescent lights at home or at work. The use of ultraviolet lamps and sunbeds, however, was associated with a significantly increased risk (relative risk = 2.9; 95% confidence interval 1.3 to 6.4), and the risk was significantly related to duration of use. The risk was particularly raised among people who have first used [corrected] ultraviolet beds or lamps more than [corrected] five years before presentation (relative risk = 9.1; 95% confidence intervals 2.0-40.6), in whom it was significantly related to cumulative hours of exposure. The risks associated with exposure to ultraviolet lamps and sunbeds remained significant after adjustment for other risk factors for melanoma.

Relation between phenotype and banal melanocytic naevi.

In a study of risk factors for the development of melanocytic naevi in relation to the pathogenesis of malignant melanoma 197 white adults were examined by four dermatologists and naevus counts correlated with several other features. Highly significant associations were found between large numbers of banal acquired melanocytic naevi and the ability to tan easily without burning (skin types 3 and 4; relative risk 4.6), brown or hazel eyes (relative risk 3.5), green or grey eyes (relative risk 3.5) and brown or black hair (relative risk 3.7). No significant associations with numbers of naevi were shown for parity or use of oral contraceptives or other steroid hormones. This is the first study to find any relation between melanocytic naevi and phenotypic factors in a white population.

Site-specific melanocytic naevus counts as predictors of whole body naevi.

Counts of melanocytic naevi of 2 mm or greater diameter on all body sites were conducted in 197 Caucasian adults in Scotland. Mean naevus numbers were greater in young than in older adults, and in females than in males. Naevus counts on the upper limbs, lower limbs, and trunk were strongly and significantly correlated with each other and with whole body counts. Thus, where whole body counts are impractical, counting naevi at any of these individual sites should provide a satisfactory method for studying naevus distribution in large populations.

Reasons for delay in primary treatment of British patients with malignant melanoma

Patients with ‘thin’ malignant melanoma (I mm thick) have excellent prospects for survival while those with tumours thicker than 3 mm have 5‐year survival figures of under 40%. It is logical to assume that the first group receive treatment more rapidly than the latter. Delay in therapy may be due to the patient, the family doctor or the specialist.

High counts of normal melanocytic naevi are a risk factor for cutaneous malignant melanoma

We have carried out a case control study on 200 patients presenting in the past 3 years with primary cutaneous malignant melanoma and 200 age‐ and sex‐matched controls. Total body melanocytic naevus counts were performed on all 400 subjects by four trained dermatologists. Analysis was by stratum matched logistic regression, with stratum matching for age, sex and city of treatment. Each variable was adjusted for the other risk factors found in the study, such as hair and eye colour, skin type, amount of UV exposure and episodes of acute sunburn.