Loss of heterozygosity (LOH) studies have been used extensively to identify regions on chromosomes that may contain putative tumour suppressor genes. We have undertaken extensive allelotyping of 45 specimens of non-small cell lung cancer (NSCLC) using 92 polymorphic microsatellite markers on 39 chromosome arms. The most frequent allelic imbalances were found on chromosome arms 3p, 9p and 17p. Significant allelic imbalance was found on other chromosome arms including, 5q (21%), 8p (19%), 13q (24%) and 17q (18%). The LOH data on 3p was subdivided into the four chromosomal regions considered to contain putative tumour suppressor genes 3p25-p24 (10%), 3p21 (10%), 3p14 (25%) and 3p13-p12 (22%). The frequency of loss in the different regions on 9p were: 9pter-p23 (31%), 9p23-p22 (45%) and 9p21-cent (30%). LOH on 17p was separated into three regions: 17pter-p13 (9%), 17p13 (33%) and 17p13-cent (22%). No correlation was found between LOH on any of the chromosomal arms and any of the clinicopathological parameters such as pathology, level of differentiation, TNM staging or alcohol intake. Only one significant association was found between LOH and tumour types. A significant difference was found between LOH on 17q in adenocarcinomas and squamous cell carcinomas (p=0.037). The fractional allele loss (FAL) values for this group of 45 NSCLC gave a median value of 0.9 (range 0-0.45). No correlation was found between FAL and nodes at pathology (p>0.05) and between FAL and tumour grade (p>0.05). No correlation was found between p53 or ras mutations in these NSCLC specimens and their FAL values. Accumulated genetic damage, as provided by this allelotype analysis, provides a useful molecular parameter by which to assess NSCLC and may, in time, assist in the determination of the clinical behaviour and clinical outcome of these tumours.

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