CYTOGENETIC STUDIES IN LYMPHOCYTES OF PATIENTS WITH RECTAL-CANCER

Spontaneous and clastogen-induced chromosomal instability in a high-ri sk group (i.e, 33 patients with rectal carcinomas) was investigated us ing peripheral blood lymphocytes as target cells. In addition to the a nalysis of spontaneous and clastogen-induced chromosome aberrations, t his study also included classical karyotype analysis and scoring of si ster chromatid exchanges (SCE) in some of the patients. Diepoxybutane (DEB), 4-nitroquinoline-1-oxide (NQO), and bleomycin were used as stan dard clastogens. Lymphocytes of healthy control individuals were studi ed in parallel with each cancer patient. While only slight but signifi cant differences could be detected of the average spontaneous, DEB- an d bleomycin (G2)-induced chromosome breakage between patient and contr ol lymphocytes, individual patients and two of the control individuals showed a more distinct increase in the frequency of the studied end p oints. These increases were documented by a variegated mosaicism of ka ryotypic changes and by an increased breakage rate induced by the clas togens. Neither the bleomycin-exposure in the G1 phase nor SCE was cap able of detecting differences between the patients and controls. Of pa rticular interest in the sense of high-risk individuals were seven pat ients and two control persons whose lymphocytes exhibited increased ch romosomal sensitivity under more than one of the studied experimental conditions.