Studies on the Walker tumor. II. Effects of adrenalectomy and hypophysectomy on tumor growth in tube-fed rats.

growths of the Walker 256 rat tumor suitable for quantitative experimentation have been described in a previous paper (14). The contributions of the adrenal and pituitary glands to the control of growth rate of intramuscular Walker tumor im plants are the subject of this paper. The study of the effects of endocrine extirpa tions is complicated by the large changes in ap petite with resultant dietary deficiencies which may accompany such procedures. In 1914 Rous (1@2) pointed out the important influence of diet on the growth of some transplantable tumors, but in sufficient attention has been paid by most other workers to the control of this factor. In more re cent years, Tannenbaum (16) has stressed the pro found influence of even moderate caloric restnic tion on the genesis of spontaneous and induced tumors. Tumors have been described as efficient â€oenitro gen traps,†• (11) in the sense that they not only compete successfully with the carcass for dietary nitrogen, but also can mobilize the substance of the host carcass for their own growth, thus producing the cachexia of advanced malignancy. However, tumor growth is not independent of diet and may be greatly affected by limitations in dietary in take. In a study of the Walker tumor, Walpole (17) demonstrated the retarding effect of progres sive starvation on the growth of this tumor, and analysis of his results reveals the severe influence of food restrictions, not only on carcass weight but also on tumor size. Inherent limitations in the pair-feeding technic have greatly reduced the value of this method of compensating for differences in dietary intake be tween experimental and control animals. Not only is accurate pair-feeding of large numbers of ani mals impossible (one is always in arrears), but, when experimental animals have greatly limited dietary intake, the pair-fed controls, which are partially starved, exhibit increased hunger activ ity and therefore are not normal. The metabolism of an intact animal on a restricted diet may differ markedly from a similar animal, the appetite of which is impaired because of the removal of an endocrine gland. In an attempt to eliminate the nonspecific ef fects of partial starvation and to obviate the objec tions to pair-feeding, we have elected to increase the dietary intake of the experimental group by tube-feeding all our animals, rather than limiting the controls. Tube-feeding is not entirely physio logical, but no effect on tumor growth …