Table 3. The 4-Year Cumulative Risk of Invasive cSCC According to History of NMSC, Severity of AK, Randomized Treatment, Additional Treatment, and Corresponding HRs.
| Characteristic | No. of patients | Cumulative risk of cSCC, % (95% CI) (n = 26) | Univariate analysis, HR (95% CI) | P value | Multivariate analysis, HR (95% CI) | P value |
|---|---|---|---|---|---|---|
| History of NMSC | ||||||
| Yes | 353 | 4.8 (2.9-7.8) | 1.21 (0.53-2.74) | .65 | 1.39 (0.60-3.19) | .44 |
| No | 271 | 2.2 (0.9-5.2) | 1 [Reference] | |||
| Severity of AK | ||||||
| Olsen grade IIIa | 49 | 20.9 (10.8-38.1) | 7.11 (3.16-15.99) | <.001 | 6.72 (2.94-15.34) | <.001 |
| Olsen grades I-II | 575 | 2.4 (1.4-4.2)b | 1 [Reference] | |||
| Randomized treatment | ||||||
| Imiquimod | 156 | 5.8 (2.9-11.3) | 2.58 (0.81-8.26) | .11 | 2.09 (0.65-6.74) | .22 |
| Methylaminolevulinate PDT | 156 | 3.6 (1.5-8.6) | 1.48 (0.42-5.26) | .54 | 1.00 (0.27-3.62) | >.99 |
| Ingenol mebutate | 157 | 3.0 (1.1-7.9) | 1.35 (0.38-4.79) | .65 | 0.86 (0.24-3.13) | .82 |
| Fluorouracil | 155 | 2.2 (0.7-6.6) | 1 [Reference] | NA | NA | NA |
| Additional treatment after end of study treatment | ||||||
| Yes | 218 | 6.4 (3.7-10.7) | 3.80 (1.61-8.97) | .002 | 3.67 (1.52-8.81) | .004 |
| No | 406 | 2.1 (1.0-4.4) | 1 [Reference] |
Abbreviations: AK, actinic keratosis; cSCC, cutaneous squamous cell carcinoma; HR, hazard ratio; NA, not applicable; NMSC, nonmelanoma skin cancer; PDT, photodynamic therapy.
a
One or more lesions of Olsen grade III.
b
No cSCCs were found in patients with Olsen grade I.