Effect of chemotherapy on tumor temperature in rats

Two transplanted rat immunocytomas with different degrees of sensitivity to single injection of cyclophosphamide (CY) were used to assess the reliability of recording of the tumoral and rectal temperatures may be useful to evaluate the efficacy of cytostatic drugs against experimental rat tumors. With the highly sensitive tumor (ISIS 130), 25 mg/m2 of CY resulted in a pronounced tumor inhibition (Treated/Control tumors = 28%); with the less sensitive (ISIS 208), a CY dose of 320 mg/m2 was necessary to inhibit tumor growth to the same extent. The more important the decrease in tumor size was, after the administration of the drug, the larger the decrease was in tumoral temperature. Since the rectal temperature remained fairly stable, there was an increase of the difference between the tumoral and rectal temperatures. From the comparison between the results obtained for the two tumors with a wide range of CY doses, it appeared that the decrease in tumoral temperature did not correlate with the drug dose itself, but with the actual antitumor efficacy of the drug in each particular case.