Among 1,953 consecutive patients with squamous cell carcinomas, basal cell carcinoma, or actinic keratosis, the average age of occurrence of actinic keratoses and basal cell carcinomas was younger than for squamous cell carcinoma. Also the occurrence of basal cell carcinoma decreased more rapidly than squamous cell carcinoma in the elderly.
Of a total of 17,767 actinic keratoses, squamous cell carcinomas, basal cell epitheliomas, and keratoacanthomas, Chi-square analysis of the seasonal occurrence of these tumors indicated that there was a statistically significant decrease in occurrence of squamous and basal cell tumors during the winter months.
During the last ten years (11,264 skin cancers), a steadily rising basal to squamous ratio was observed.