Tumorigenic effect of some commonly used moisturizing creams when applied topically to UVB-pretreated high-risk mice

Abstract

Irradiation of SKH-1 mice with UVB (30 mJ cm(-2)) twice a week for 20 weeks resulted in mice with a high risk of developing skin tumors over the next several months in the absence of further irradiation with UVB (high-risk mice). Topical applications of 100 mg of Dermabase, Dermovan, Eucerin Original Moisturizing Cream (Eucerin), or Vanicream once a day, 5 days a week for 17 weeks to these high-risk mice increased significantly the rate of formation of tumors and the rate of increase in tumor size per mouse. Additional studies indicated that treatment of high-risk mice with Dermabase, Dermovan, Eucerin, or Vanicream for 17 weeks increased the total number of histologically characterized tumors by 69% (average of two experiments; P<0.0001 in each experiment), 95% (P<0.0001), 24% (P<0.01), and 58% (P<0.0001), respectively. Topical applications of a specially designed Custom Blend cream to high-risk mice was not tumorigenic. The results indicate that several commercially available moisturizing creams increase the rate of formation and number of tumors when applied topically to UVB-pretreated high-risk mice. Further studies are needed to determine the effects of topical applications of moisturizing creams on sunlight-induced skin cancer in humans.

Figure 1. Time course for the effect of topical applications of different moisturizing creams on the formation of tumors in “high-risk” mice pretreated with UVB

Female SKH-1 hairless mice were treated with UVB (30 mJ cm⁻²) twice a week for 20 weeks to obtain tumor-free “high-risk” mice. The mice were then untreated, treated topically with water (100 μl) or with the indicated cream (100 mg) once a day, 5 days a week for 17 weeks in the absence of further treatment with UVB. The data are expressed as the mean ± SE. Statistical analyses of differences in pair-wise regression slopes of rates of change with time were determined for tumors per mouse and for tumor volume per mouse as described in the Materials and Methods section. The statistical analysis of changes in the percent of mice with tumors versus time was based on a comparison of tumor-free distribution between the two groups by the log-rank test as described in the Materials and Methods section. Statistically significant differences from the water-treated control group (P < 0.05) are indicated.

Figure 1. Time course for the effect of topical applications of different moisturizing creams on the formation of tumors in “high-risk” mice pretreated with UVB

Female SKH-1 hairless mice were treated with UVB (30 mJ cm⁻²) twice a week for 20 weeks to obtain tumor-free “high-risk” mice. The mice were then untreated, treated topically with water (100 μl) or with the indicated cream (100 mg) once a day, 5 days a week for 17 weeks in the absence of further treatment with UVB. The data are expressed as the mean ± SE. Statistical analyses of differences in pair-wise regression slopes of rates of change with time were determined for tumors per mouse and for tumor volume per mouse as described in the Materials and Methods section. The statistical analysis of changes in the percent of mice with tumors versus time was based on a comparison of tumor-free distribution between the two groups by the log-rank test as described in the Materials and Methods section. Statistically significant differences from the water-treated control group (P < 0.05) are indicated.