The authors conducted a study of 404 melanoma patients and 521 control patients of both sexes at Roswell Park Memorial Institute. As have previous investigators, they found that higher risk attaches to upper socioeconomic status, as measured by occupation and education, lightness of complexion and hair, and amount of blue in the admixture of eye color. The authors also found a higher risk among individuals who reacted to sun exposure by burning, blistering, or freckling rather than by tanning. A particular concern was to measure risk associated with exposure to the sun. As have two other investigators, they found that risk decreased with increasing exposure, suggesting either that individuals continually exposed to the sun have less risk because of tanning, or that susceptibles purposely avoid sun exposure, or both. The fact that melanoma occurs with greater frequency on sites exposed to the sun suggests that sun exposure plays a part. These studies showed a dose-response increase in risk (odds ratios of up to 4 for males and over 6 for females) with increases in number of traits possessed, such as light complexion, and burning or freckling in response to sun exposure. This is consistent with the authors' earlier finding of a strong familial aggregation of melanoma.