Activity of Prostatic Cancer*

We have observed that the serum proteins of patients with advanced prostatic cancer rapidly return to or toward normal values following de activation of the neoplasm by anti-androgenic procedures. While there exists a variety of meth ods, more or less satifactory, for observing these changes, perhaps none is so simple or so useful as the determination of the lowest percentage of blood serum to gel after heating under standard conditions. The use of this assay method is the subject of the present paper. One of the central problems in the chemotherapy of cancer is to obtain methods of measuring neo plastic activity and the effects of medicines thereon, with precision and sensitivity, preferably with simplicity. Advanced prostatic carcinoma of man is peculiarly adaptable for quantitative studies of activity and, conversely, partial or com plete inactivation of the tumor by therapeutic agents. In the past this neoplastic activity could be measured by two modalities which reflected local events in and near the carcinoma. When this neoplasm has metastasized, the level of acid phos phatase in serum is often increased (3) . A common site of metastasis of this tumor is bone marrow, a tissue wherein the neoplasm thrives and usually stimulates the growth of osteoblasts, which process in turn results in an elevation of alkaline phosphatase (9) in the serum. When one investi gates (7) these enzymatic levels in the blood con currently over a period of days, he measures the relative production of acid phosphatase by the metastases (an activity of the cancer) and the re sponse of adjacent nonmalignant bone tissue to the presence of that tumor (local reactivity of normal host cells) . Unlike these measurements of essentially local changes, albeit occurring in many places, a determination of the least percentage of thermocoagulable protein reflects the over-all