Histamine synthesis and content in benign and malignant breast tumours. Its effects on other host tissues.

We studied 100 patients: 40 with breast cancer, 41 with benign breast tumours and 19 non-cancer-bearing cholecystectomy patients, in order to measure the histidine decarboxylase activity and histamine content in benign and malignant breast tumours, and to determine whether the histamine metabolism affected skin and muscle tissue distant from the tumour. The HDC-activity of cancerous tissue was significantly higher (P < 0.01) than that registered in the healthy mammary gland tissue of the same patient, being even more pronounced in benign tumour tissue (P < 0.001). However, the histamine content was found to be significantly lower (P < 0.01) in malignant tumours, but higher in benign tumoural tissue as compared with the healthy tissue of the same patient. We also found that the histamine content in muscle tissue was significantly higher in cancer patients than in non-cancer patients. These findings highlight the fact that intracellular histamine metabolism varies in benign and malignant tumours, and that high histamine synthesis of malignant tumours affects other host tissue.