Chromosomal radiosensitivity in G(2)-phase lymphocytes identifies breast cancer patients with distinctive tumour characteristics

A substantial proportion of women with breast cancer exhibit an abnormally high radiosensitivity as measured by the frequency of chromatid breaks indu ced in G(2)-phase, PHA stimulated lymphocytes. Chromatid break frequencies were compared for a cohort of previously untreated sporadic breast cancer p atients and hospital outpatient controls, In the breast cancer group 46% sh owed high radiosensitivity compared to 14% of controls (P < 0.001). Compari son of those breast cancer patients with a high G(2) radiosensitivity (G(2) RS) versus those with a low G(2)RS showed no difference in menopausal statu s or age but the high G(2)RS group had on average a lower score on the Nott ingham Prognostic Index. Predicted survival in the high G(2)RS group at 15 years was 55% compared to 36% for the low G(2)RS group. Furthermore, 81% of tumours from the high G(2)RS were oestrogen receptor positive compared to 45% from the low G(2)RS group. Thus high G(2)RS identifies a sub-population of patients with distinctive tumour characteristics and with a predicted i mproved prognosis as compared with those in the low G(2)RS group. Our findi ngs imply that besides influencing risk of breast cancer the genetic factor s determining G(2) radiosensitivity also influence the tumour characteristi cs and prognosis in these patients. (C) 2001 Cancer Research Campaign.