Melanocytic Nevi and Risk of Cutaneous Malignant Melanoma in Southern Spain

Abstract

The main objective of this study was to assess whether cutaneous malignant melanoma (CMM) shows a stronger relation with the melanocytic nevi count at the site where CMM was diagnosed than with the melanocytic nevi count at other sites, stratifying by histologic CMM type, in a southern Mediterranean population. Cases and controls were selected from a population in southern Spain in 1988-1993. The study population included 116 incident cases with non-familial CMM (International Classification of Diseases 9th Revision (ICD-9) code 172), and 116 controls matched 1:1 for sex and age (+/- 4 years). Data were collected by personal interview, and melanocytic nevi were counted over the entire body surface by clinical skin examination performed by a dermatologist. Crude and multiple risk factor-adjusted odds ratios and 95% confidence intervals were computed by conditional logistic regression analysis. After adjustment by skin type, unexposed skin color, and sun exposure, CMM was found to occur significantly more frequently in individuals with a high number of melanocytic nevi at the same site where CMM originated (odds ratio (OR) for >8 nevi = 12.0, 95% confidence interval (CI) 1.3-108.2). The ability to predict the number of melanocytic nevi on different anatomic sites on CMM, but excluding the CMM cases on each corresponding site, was also examined. A significant trend with the number of nevi on the anterior surface of thighs was found (OR for >4 nevi = 4.5, 95% CI 1.4-14.9). Melanocytic nevi count on the melanoma site was the variable most closely related to superficial spreading melanoma subtype (SSM) (OR for >8 nevi = 82.19, 95% CI 2.72-2,454). On the other hand, the number of melanocytic nevi on the melanoma site was unrelated to risk of CMM subtypes other than SSM. These results support the hypothesis that nevi are an important risk factor for melanoma, especially SSM, in populations with a darker ethnic background.

Number of acquired melanocytic nevi in patients with melanoma and control subjects in Japan: nevus count is a significant risk factor for nonacral melanoma but not for acral melanoma

“…The current study could not confirm the report that the number of acquired nevi on palms was related with the development of superficial spreading melanoma. 29 The relationship between the diameter of acquired melanocytic nevi and the risk of melanoma development has been reported in several studies. 4,30,31 Naldi et al 4 confirmed that, in an Italian population, large nevi (Ͼ6 mm in diameter) add to the risk of melanoma independently of the count of smaller melanocytic nevi.…”

A comparison of several procedures to estimate the confidence interval for attributable risk in case-control studies

“…To illustrate the application of these methods in individually matched studies, we use a matched study on the risk factors for cutaneous malignant melanoma, in which 116 cases with a histologically con"rmed non-familial cutaneous malignant melanoma diagnosed in the referral centre for three provinces were matched by age and sex to 116 controls [9]. We applied conditional logistic regression analysis to estimate the risk associated with skin colour, total number of hours of recreational sun exposure, total number of hours of occupational sun exposure, fototype (classi-"ed according to Fitzpatrick [10] in six sun-reactive skin types from I"always burn, never tan to VI"never burn, black skin) and total number of nevi on the melanoma site.…”

Sun Exposure, Phenotypic Characteristics, and Cutaneous Malignant Melanoma. An Analysis According to Different Clinico-Pathological Variants and Anatomic Locations (Italy)

“…Moreover, in that study, propensity to sunburn seemed to increase strongly the risk of SSM, as compared to NM. In two case-control studies, one from Spain [17] and the other from Germany [18], the number of melanocytic nevi on the melanoma site was strongly related to the risk of SSM only. On the other hand, a population-based case-control study on Swedish children and teenagers found that the presence of raised nevi on the arm had a tendency to be closer related to NM (odds ratio, OR = 4.3) than SSM (OR = 1.6) [19].…”