The results suggest a role for smoking and possibly also for other lifestyle factors in the risk of contracting BCC.

No abstract

The anamnestic skin phototypes (ASP) I-IV of 22 Caucasian volunteers wee compared with their phototested skin phototypes (PSP) using solar simulating, broadband UV radiation. The Commission Internationale de l'Eclairage (CIE)-weighted (i.e. erythemally effective) minimal erythema doses (MED) for solar simulating radiation varied from 20 mJ/cm2 (PSP type 1) to 57 mJ/cm2 (PSP type 4). In only 11 of 21 volunteers did the ASP (I-IV) and PSP (1-4) classifications coincide, and the MED values of the volunteers within the different ASP groups (I-IV) overlapped considerably. To compare the reactivity to erythematogenic radiation of different wavelengths, narrowband monochromator irradiations were performed at 298 nm, 310 nm and 330 nm. The CIE-weighted MED values at these wavelengths (20-80 mJ/cm2) corresponded well with those obtained in the broadband testing. Our results indicate that, with classification by interrogation, Caucasian skin can reliably be classified into only two subtypes, corresponding to Fitzpatrick phototypes I-III and phototype IV, respectively. A classification into four sensitivity types can be achieved by phototesting, only. We propose that the concept of ASP should be used with caution. The concept of PSP 1-4 should be favored.

Components of variance in liability were estimated by structural equation modelling. There was an elevated risk of basal cell carcinoma for the co-twin of a diseased twin, but no difference in risk by zygosity. During the prospective follow-up in 1976-96, the probandwise concordance was 7.7% in monozygotic and 7.0% in dizygotic pairs. Model fitting indicated that genetic factors were not needed to account for the distribution of basal cell carcinoma in twin pairs. These results confirm the major role of environmental factors in the aetiology of basal cell carcinoma.

The near-total lack of concordance for skin cancer in twin pairs suggests that environmental and not hereditary effects are most important in the causation of malignant skin cancers in a white population with low levels of sun exposure.