Pain relief after hypophysectomy.

Thirteen series of patients who underwent surgical or chemical hypophysectomy for the relief of pain associated with cancer were reviewed. In 10 series, involving 334 patients with breast or prostate cancer, surgical hypophysectomy produced pain relief in 70% of the patients afflicted with either tumor, including some with no evidence of hormone dependence. These results were then compared with the results of chemical hypophysectomy. This procedure was performed in 3 series involving 533 patients, of whom 24% had cancer other than breast or prostate. Chemical hypophysectomy produced pain relief in over 75% of the patients, regardless of tumor type or hormonal dependence. The possible role of the pituitary, the hypothalamus, and endogenous opiates in mediating the pain relief associated with hypophysectomy was examined. The mechanism by which pain relief is achieved remains unclear, but there is significant evidence that this relief is not related directly to the expected fall in the levels of known pituitary hormones. Evidence is provided that pain relief is the result of a hypothalamic pain-suppressing capability triggered by hypophysectomy. On the basis of both clinical data and the mechanism of action, we conclude that surgical and chemical hypophysectomy are fundamentally similar procedures.