Loss of heterozygosity at 18q21 is indicative of recurrence and therefore poor prognosis in a subset of colorectal cancers

Adjuvant therapies are increasingly used in colorectal cancers for the prev ention of recurrence. These therapies have side-effects and should, thus, b e used only if really beneficial. However, the development of recurrence ca nnot be predicted reliably at the moment of diagnosis, and targeting of adj uvant therapies is thus based only on the primary stage of the cancer. Loss of heterozygosity (LOH) in the long arm of chromosome 18 is suggested to b e related to poor survival and possibly to the development of metastases. W e studied the value of LOH at 18q21 as a marker of colorectal cancer progno sis, association with clinicopathological variables, tumour recurrence and survival of the patients. Of the 255 patients studied, 195 were informative as regards LOH status when analysed in primary colorectal cancer specimens using the polymerase chain reaction (PCR) and fragment analysis. LOH at 18 q21 was significantly associated with the development of recurrence (P = 0. 01) and indicated poor survival in patients of Dukes' classes B and C, in w hich most recurrences (82%) occurred. An increased rate of tumour recurrenc e is the reason for poor survival among patients with LOH at 18q21 in prima ry cancer. These patients are a possible target group for recurrence-preven ting adjuvant therapies.