Nambour Community-based Skin Cancer Prevention Trial

INTERVENTION: "Daily sunscreen, Beta‐carotene supplements" Daily sunscreen: (Sun Protection Factor (SPF) 15+, to be applied to head, neck, arms and hands every morning (and to reapply after heavy sweating, bathing, or long sun exposure), for 5 years. Beta‐carotene supplements: 30mg once daily as oral capsule, for 5 years. 4 arms in trial viz. Arm 1: daily sunscreen, beta‐carotene supplements Arm 2: daily sunscreen, placebo supplements Arm 3: beta‐carotene supplements, discretionary sunscreen Arm 4: discretionary sunscreen, placebo supplements CONDITION: basal cell carcinoma blood lipids as assessed by fasting blood tests cutaneous melanoma photoageing solar keratoses squamous cell carcinoma of the skin PRIMARY OUTCOME: basal cell carcinoma (BCC) incidence: ascertained by clinical examination and medical records; histologically‐confirmed photogeing severity: assessed clinically and by microtopography using silicon casts of the back of the hand solar keratosis (SK) prevalence: SK clinically diagnosed by dermatologists squamous cell carcinoma (SCC) incidence: ascertained by clinical examination and medical records; histologically‐confirmed SECONDARY OUTCOME: blood lipids as assessed fasting blood test melanoma incidence: melanomas ascertained through medical records and cancer registry; histologically‐confirmed and reviewed INCLUSION CRITERIA: Registered on the state electoral roll for Nambour in Nov 1986