Recent studies on cancer genetics are consantreted on chromosomal abnormalities occuring in tumour tissue including chromosomal fragile sites, deletions and translocations. We have planned this investigation to determine the chromosomal loci where fragile sites are located.

Lymphocyte cultures were establıshed from 28 cancer patients and 30 controls with normal control subjects were established. By the application of GTG banding technique to chromosomes, fragile sites were detected cytogenetically. Fifty cells were evaluated for each individual. It was determined that the majority of the fragile sites were 5q, 2q, 3q, 13q, 4q, 3p, 15q and 1q, The incidence of fragile site between the patient and the control groups were statistically significant(x²=44.8 P<0.01). Our results of fragile sites were compatible with the results.

It was determined that fragile sites were different in various tumour types. The marginal fragile sites amoung study groups were 2q and 5q.

In conclusion, the fragile sites specific to various cancer types were determined. These results confirm that these fragile sites can establish a basis for the molecular analyses in the sporadic and familial cancers. Therefore in the cases of cancers, analyses of fragile sites could be used as an indicator.