Heptaldehyde as a Tumor Inhibitor. ∗

Abstract

In connection with studies on tumor-inhibition by oil of wintergreen, Strong identified heptaldehyde in the active fraction of the oil. 1 2 3 He then fed a diet containing commercial heptaldehyde to mice with spontaneous tumors, and observed liquefaction in most of the tumors followed in many cases by regression. More recently, Strong and Whitney reported a similar response in dogs with spontaneous mammary tumors when heptaldehyde was injected subcutaneously. 4

The question arose whether heptaldehyde would inhibit all tumors or whether its action was restricted to certain tumor types. We have, therefore, studied the effect of heptaldehyde on 5 kinds of mouse tumors: (1) spontaneous mammary adenocarcinoma in strain A mice, (2) primary ear tumor induced by ultraviolet light, (3) primary epithelial tumor induced by painting benzpyrene, (4) primary sarcoma induced by the subcutaneous injection of benzpyrene, (5) transplantable spindle-cell sarcoma originally induced by benzpyrene.

The heptaldehyde (Eastman technical) was fed mixed in various amounts with Steenbock stock ration† (Table I). In general the mice were placed on the diets when the tumors were approximately one centimeter in diameter, although some of the spontaneous tumors were larger. The mice with transplantable tumors were given the various diets from the day of inoculation. In each series the animals were divided such that the tumors in the various groups were of comparable sizes. The tumors were measured at weekly intervals and all mice were carefully autopsied.

When 2% heptaldehyde was fed to mice bearing U.V. tumors, the tumors grew more slowly than in animals on the stock diet. However, these mice ate so little that the limiting factor in the growth of the tumors appeared to Ix the reduced caloric intake rather than the heptaldehyde. This was demonstrated by feeding stock ration to tumor-bearing mice in the small amounts consumed by the animals receiving 2% heptaldehyde. Under these conditions the growth rate of the tumors was also markedly restricted.