Table 4.

Relative risks of skin cancer according to quintiles of cumulative UV flux stratified by host risk score in the Nurses' Health Study II (1989–2009)

Low host risk scoreaHigh host risk scorea
CasesAge-adjusted RR (95% CI)MV-adjusted RRb (95% CI)CasesAge-adjusted RR (95% CI)MV-adjusted RRb (95% CI)P-value for interactionc
BCC
 Quintile 12241.001.004401.001.000.758
 Quintile 22811.45 (0.99–2.11)1.43 (0.98–2.08)5481.33 (1.02–1.72)1.30 (1.00–1.68)
 Quintile 34132.01 (1.30–3.10)1.97 (1.28–3.04)6691.52 (1.12–2.05)1.47 (1.09–1.98)
 Quintile 46971.90 (1.19–3.03)1.87 (1.18–2.98)13262.00 (1.45–2.76)1.93 (1.40–2.66)
 Quintile 58172.51 (1.56–4.03)2.45 (1.53–3.94)15402.41 (1.74–3.35)2.30 (1.66–3.19)
Ptrend<0.0001<0.0001<0.0001<0.0001
SCC
 Quintile 1151.001.00301.001.000.205
 Quintile 2301.14 (0.35–3.73)1.15 (0.36–3.71)611.49 (0.63–3.51)1.48 (0.63–3.49)
 Quintile 3502.08 (0.56–7.77)2.15 (0.58–7.95)1061.48 (0.56–3.89)1.47 (0.56–3.87)
 Quintile 4973.14 (0.78–12.6)3.29 (0.83–13.0)1801.70 (0.62–4.65)1.69 (0.62–4.63)
 Quintile 51184.03 (0.98–16.5)4.27 (1.05–17.3)1931.89 (0.68–5.25)1.88 (0.68–5.23)
Ptrend0.010.0080.160.17
Melanoma
 Quintile 1291.001.00681.001.000.423
 Quintile 2310.44 (0.15–1.28)0.45 (0.16–1.30)1280.87 (0.48–1.59)0.87 (0.48–1.58)
 Quintile 3470.50 (0.15–1.70)0.51 (0.15–1.71)1020.64 (0.32–1.29)0.63 (0.32–1.25)
 Quintile 4670.53 (0.14–1.95)0.53 (0.14–1.94)1510.84 (0.39–1.79)0.81 (0.38–1.72)
 Quintile 5400.47 (0.12–1.80)0.46 (0.12–1.76)1160.83 (0.38–1.84)0.80 (0.36–1.75)
Ptrend0.510.440.900.71
  • aWe used the lowest quintile with each subgroup as the reference.

  • bMV-adjusted RR: multivariable analysis controlled for covariates listed in Table 2 (footnote b).

  • cWe tested the significance of the interaction with a likelihood ratio test by comparing a model with the main effects of cumulative UV flux and host risk profile and their interaction terms with a reduced model with only the main effects.