HIGH-FREQUENCY OF LOH AT CHROMOSOME 18Q IN HUMAN BREAST-CANCER - ASSOCIATION WITH HIGH S-PHASE FRACTION AND LOW PROGESTERONE-RECEPTOR CONTENT

Human primary breast cancers were analysed for somatic loss of heteroz ygosity (LOH) at chromosome 18 with 15 polymorphic microsatellite mark ers. LOH was observed in 148 of the 228 cases analyzed (65%). Three sm allest common deletion regions (SCDR) were detected on the long arm of chromosome 18. The marker D18S51 at the region 18q22 showed the highe st LOH (42%). Tumors with and without LOH at 18q were tested for assoc iation with clinico-pathological features of the tumors, such as estro gen and progesterone receptor content, age at diagnosis, tumor size, n ode status, histological type, S-phase fraction DNA ploidy and LOH at other chromosomal regions. A significant association was found between LOH at 18q and high S-phase fraction (99.9% confidence interval) and low progesterone receptor. content (99%, confidence interval). Further more, an association was found between LOH at 18q and LOH at 1p, 7q, 9 p, 13q and 17q. We conclude that there are three separate LOH target r egions at chromosome 18q and that inactivation of one or. mole genes a t these regions might be important for human breast carcinogenesis.