The paradoxical effects of splenectomy on tumor growth.

BACKGROUND

There is a vast and contradictory literature concerning the effect of the spleen and particularly of splenectomy on tumor growth. Sometimes splenectomy seems to inhibit tumor growth, but in other cases it seems, paradoxically, to facilitate both oncogenesis and the growth of established tumors.

APPROACH

In this essay I have selected from this large literature a few papers that seem particularly instructive, in the hope of extracting some understanding of the rules governing this paradoxical behavior.

CONCLUSION

In general, whether splenectomy enhances or inhibits tumor growth seems to depend primarily upon the ratio of spleen to tumor. Small proportions of spleen cells usually stimulate tumor growth, in which case splenectomy is inhibitory. Larger proportions of the same cells, especially if they are from immunized animals, usually inhibit tumor growth, in which case splenectomy results in tumor stimulation.