Resistance of Thyroparathyroidectomized Rats to Growth of a Spindle-Cell Sarcoma

Abstract

The published reports on the effect of thyroidectomy on neoplastic growth present divergent opinions. Rohdenburg, Bullock and Johnston1 in a series of 29 thyroidectomized rats found at 40 days after inoculation with Flexner-Jobling carcinoma 52 % of "cures" against only 16% of regressions in the control group. Recently Bischoff and Maxwell2 inoculated 13 thyroparathyroidectomized rats with rat carcinoma 256. Based on a comparison with 16 inoculated litter-mate controls they observed "no sign'ificant difference in percentage of takes, rate of tumor growth, or final mortality".Our tumor, a sarcoma, which arose spontaneously in a rat uterus has been transplanted during the past three years into more than lo00 rats. Successfully inoculated tumors in normal rats have not been seen to regress. This is mentioned to indicate that a spontaneous regression of this tumor, if it does occur, 5s uncommon. The operation consists of complete ablation of thyroid and parathyroid glands. All rats were from our colony of Wistar Institute albino stock. All individuals of the litters, or groups, were inoculated bilaterally into groin pockets from the sama tumor and a t the same time.In Table I where the tabulation is by litters the 4 longest postthyroidectomy ones ( 1 , 2, 3, 4) are placed first. Of the 18 successful takes in this group 14 completely regressed. This high percentage (77%) of regressions in a group where the shortest postthyroidectomy period was 112 days is in contrast with 25% of regressions in all successfully inoculated remaining rats with shorter post-operative periods. In both groups it is seen that a first inoculation may fail and a second one succeed. This is true also for normal control animals, and sometimes may result from the accidental introduction of bacteria into the pocket. In the rats with relatively short post-thyroidectomy periods there is an usual tendency for the second inoculation tumors to regress. This may be explained in

Hyperthyroidism, Niacin, and Isonicotinic Acid Hydrazide (INAH): Effects on Sarcoma 180

“…It seems unlikely that experimental hypothyroidism would result in opposite effects, the literature being clouded in a manner similar to that concerning the hyperthyroidic state. Several authors have reported results utilizing chemical or mechanical thyroidectomy with decreased tumor size or incidence or delayed time of onset [8,14,19,23] while some have reported the opposite or no effect [25,28,33].…”