A case-control study of malignant melanoma in Israeli kibbutzim

Incidence rates for malignant melanoma in Israel are rising steadily, and the kibbutz population is at increased risk for this malignancy.

To assess the risk factors for malignant melanoma among kibbutz members compared to matched healthy controls.

We conducted a case-control study of 168 malignant melanoma patients and 325 healthy controls, matched by age and gender. Data were collected on three categories of risk: demographic, personal (e.g., skin, eye and hair color), and environmental/behavioral (e.g., sun exposure, use of sunscreens).

There were no differences between the groups regarding sociodemographic data. Significantly more patients than controls had fair, vulnerable skin (P < 0.001), light eyes (P < 0.05), and fair hair (P < 0.001). There was no difference in family history of malignant melanoma or other cancers. Patients with malignant melanoma had significantly more additional skin lesions (e.g., keratoses) (P < 0.001). More patients than controls recalled having been exposed to the sun for long periods when they were 6-13 years of age. A conditional logistic regression analysis showed that fair hair, fair vulnerable skin, and additional skin lesions were independently associated with malignant melanoma (P < 0.01).

The main target population for interventions to reduce the incidence of malignant melanoma among kibbutz members should be individuals with these risk factors. A history of increased exposure to the sun from age 6 to 13 should also be taken into account as an independent risk factor.