Metastatic cancer in guinea pigs irradiated with grenz rays

Guinea pigs were irradiated with 100, 200, or 300 rads of grenz rays four times weekly for two years (total doses were 32,600, 65,200, and 94,500 rads) and observed for an additional three years for development of cancer. Four animals of 11 developed squamous cell carcinomas. Three of the animals with squamous cell carcinoma of the skin had metastases in regional lymph nodes. The neoplastic cells showed the same degree of differentiation in the primary tumors as in lymph nodes.