Table II.
Immunohistologic staining for markers of UV-induced oxidative stress
| Variable | Patients* | Percent 8-OG (mean, ±SD) | Univariate analysis | |
|---|---|---|---|---|
| Control | UV-irradiated | P value# | ||
| Treatment | ||||
| Placebo | 49 (51%) | 33.1 ±24.2 | 96.2 ±7.5∥ | |
| Drug | 48 (49%) | 33.6 ±25.1 | 94.6 ±12.3 | 0.65 |
| MC1R status | ||||
| Low-risk | 48 (49%) | 35.9 ± 26.9 | 95.8 ± 11.0 | |
| High-risk | 49 (51%) | 30.8 ± 21.9 | 95.0 ± 9.3 | 0.48 |
| Log (x100) TR-1 (mean, ±SD) | Univariate analysis | |||
| Control | UV-irradiated | Effect ratio┼ (95% CI), P value | ||
| Treatment | ||||
| Placebo | 50 (51%) | 1.05 ±0.76 | 1.26 ±0.70╪ | 1.00 |
| Drug | 49 (49%) | 1.16 ±0.58 | 1.28 ±0.55 | 0.94 (0.81 – 1.10), 0.43 |
| MC1R status | ||||
| Low-risk | 49∥ (49%) | 1.00 | ||
| High-risk | 50 (51%) | 0.95 (0.82 – 1.11), 0.54 | ||
One subject with low-risk MC1R randomized to drug was excluded from both analyses because the lesions removed were seborrheic keratoses and not nevi, and two subjects (one high-risk MC1R randomized to drug and one low-risk MC1R randomized to placebo) were excluded from analysis of 8-OG because there was insufficient tissue.
Wilcoxon test was used to assess significance of differences in the median percent nevus melanocytes with 8-OG expression in the UV-irradiated nevus compared to that in the control (unirradiated) nevus. Additional analyses of 8-OG response with gender, height, weight, hair color, and eye color as covariates did not reveal any significant predictors (not shown).
For placebo group, difference between control and UV-irradiated was significant (P<0.001, Wilcoxon test).
The effect ratio is the ratio of log TR-1 expression in nevus melanocytes in the UV-irradiated nevus compared to that in the control (unirradiated) nevus. Additional analyses of TR-1 response with age, gender, height, weight, hair color, and eye color as covariates did not reveal any significant predictors (not shown).
For placebo group, difference between control and UV-irradiated was significant (P=0.003, Wilcoxon test).
We tested for potential interaction between treatment and MC1R status for both analyses, and did not find significance for either (not shown).