Ehvidence
Favorable Efficacy (RCT)

Sunscreen for skin cancer prevention

Daily broad-spectrum sunscreen vs. Discretionary/usual sunscreen use · for Skin cancer (general adult population) · real-time analysis of 3 studies · updated 2026-05-29

In the randomized Nambour trial, regular daily sunscreen reduced squamous-cell carcinoma and, on long-term follow-up, invasive melanoma, but did not significantly reduce basal-cell carcinoma. Benefits are in a general-population setting, so the absolute reductions are modest.

Efficacy (RCT): Efficacy evidence on clinical outcomes. Effects are risk ratios with number-needed-to-treat where a baseline risk is available. Glossary →

Interpretation & tips

The clearest randomized benefit is for squamous-cell carcinoma; basal-cell was null. Long-term follow-up found fewer melanomas (significant for invasive). This was a general-population trial, so absolute benefit is modest (large NNT)—unlike chemoprevention in high-risk patients.

39% lower risk of squamous-cell carcinoma
Pooled RR 0.61 (95% CI 0.46–0.81) across 1 studies, 3,242 patients (random-effects, I² 0%).
0.61
Pooled RR
0.46–0.81
95% CI
1
Studies
3,242
Patients
—
NNT

Forest plot—Squamous-cell carcinoma

Nambour follow-up (van der Pols) 2006 0.62 [0.38–0.99] Nambour (Green) 1999 0.61 [0.46–0.81] Pooled (RE) 0.61 [0.46–0.81] 0.1 0.25 0.5 1 2 4 ← favors treatment favors control →

Study results—Squamous-cell carcinoma

Study Design Dose / regimen Treatment Control RR [95% CI] Improvement NNT Weight
Nambour follow-up (van der Pols) 2006 excl note RCT Daily SPF 15+ — — 0.62 [0.38–0.99] 38% — —
Nambour (Green) 1999 note RCT Daily SPF 15+ — — 0.61 [0.46–0.81] 39% — 100%

RR < 1 favors treatment for outcomes where lower is better. Rows in gray have a confidence interval crossing 1 (individually inconclusive). “~” marks effects reported as OR/HR and treated as RR-approximations. “excl” = excluded from pooling (e.g. reviews).

Notes & interpretation

  • Nambour follow-up (van der Pols) 2006—8-year follow-up of the same cohort (sustained effect); excluded from pooling to avoid double-counting.
  • Nambour (Green) 1999—Squamous-cell carcinoma tumor rate ratio over the trial period.

Background

The Nambour Skin Cancer Prevention Trial randomized 1,621 general-population adults in Queensland, Australia to daily application of SPF 15+ sunscreen versus discretionary use (factorially crossed with beta-carotene). Outcomes were tracked over the 4.5-year trial and in long-term follow-up.

Topic methodology & caveats

Published tumor rate ratios and hazard ratios with 95% CIs. The 8-year squamous-cell follow-up (same cohort) is shown for context and excluded from pooling. No control risk is encoded, so NNT is not shown.

Studies