Allelic loss on chromosome 9q is associated with lymph node metastasis of primary breast cancer

Frequent allelic losses on chromosome 9 are seen in a wide variety of human tumors; moreover, two genes (P16 and PTC) whose mutant alleles confer pred ispositions to some inherited cancer syndromes have been identified on this chromosome. Using 15 highly polymorphic microsatellite markers distributed on both arms of chromosome 9, we tested 96 primary breast carcinomas for a llelic loss in order to define the locations of genes that might be involve d in this type of tumor, Allelic loss was observed in 37 of the tumors (39% ) and detailed deletion mapping identified target regions at 9p21, 9q22.3 a nd 9q33. Losses at 9q22.3 and 9q33 were correlated with the presence of lym ph node metastasis, and allelic loss at 9q22.3 was observed more frequently in scirrhous tumors than in less aggressive histologic types. Therefore, i nactivation of tumor suppressor genes in 9q22.3 and 9q33 regions might play a role in progression of breast cancers, especially in metastasis to lymph nodes and in development of scirrhous turners.