Are retroviruses involved in the aetiology of human breast cancer?
To further investigate the possibility for retroviral involvement in the etiology of human breast cancer we processed peripheral blood monocytes and malignant breast tissue biopsies from 10 patients with breast cancer (infiltrating ductal carcinoma or infiltrating lobular carcinoma; ages 40-80 years) and 20 normal healthy women (with no evidence or family history of breast cancer. 10 age-matched controls and 10 women age 22-27 years) for the assay of the retroviral enzyme, reverse transcriptase, using an ELISA and for election microscopy examination for the detection of retroviral-like particles. Reverse transcriptase activity was detected in 5 out of 10 samples of monocyte culture medium and in 1 out of 10 of malignant tissue biopsies from the patients with breast cancer. In contrast, reverse transcriptase was not detected in the culture medium of the monocytes from any of the control subjects. Electron microscopy did not reveal the presence of any retroviral-like particles in any sam
