Long-term effects on the immune system following local radiation therapy for breast cancer. III. Changes of spontaneous and lectin dependent cellular cytotoxicity.

Long-term effects of local radiotherapy (45 Gy) on the spontaneous and PHA-mediated cytotoxicity of the peripheral blood lymphocyte population was studied in disease-free breast cancer patients 5-6 and 10-11 years after treatment. The patients were all part of a randomized trial in which pre- or post-operative radiotherapy was evaluated against surgery only. PHA-mediated cytotoxicity for 51Cr-labelled chicken erythrocytes seemed to be somewhat increased in patients who were irradiated 5-6 years earlier (p less than 0.025). This increase was not detectable after a disease-free period of 10-11 years. No significant differences between the various treatment groups were observed for spontaneous cytotoxicity against Chang and K 562 cells. The proportion of Leu 7+ lymphocytes was significantly increased in patients who received radiation therapy 5-6 years earlier (p = 0.029) and there was a significant correlation between PHA-mediated cytotoxicity and proportion of Leu7+ cells.