Effect of a small dose of x-radiation on local recurrence of tumors in rats and mice.

Abstract

The incidence of local recurrence of carcinosarcoma 256 Walker in rats and a mouse tumor in mice was studied after administration of a small dose of x radiation. The mammary tumor occurring spontaneously in C3H/HeJ mice was transplanted into first generation offspring and can be considered isologous. The rat tumor was grown in the subcutaneous tissues of the back for 9 days and the mouse tumor for 30 days; excision at these times was followed by a high incidence of local recurrence. X radiation (2,000 rads) was given to the tumor 24 hours before operation or to the operative site 24 hours after excision of the growth; the same dose was given to the normal tissues of the controls on the day of operation. It was found that the preoperative radiation decreased the incidence of local recurrence of both tumors. Postoperative radiation was less effective; it decreased recurrences of the carcinosarcoma 256 Walker in the rat but only delayed the appearance of the mouse tumor.