Multiple chromosomal underrepresentations detected by interphase cytogenetics - possible prognostic markers in head and neck tumors?

Relevant prognostic factors for head and neck squamous cell carcinoma are tumor extension (pT), occurrence of lymph node metastases (pN) and grade of differentiation (G). We tried to correlate these histological characteristics with numerical aberrations of whole chromosomes as demonstrated by fluorescence in situ hybridization techniques (FISH). Therefore, we investigated isolated interphase cells from paraffin sections of squamous cell carcinomas of the head and neck region from 46 patients with centromeric DNA probes for chromosomes 1, 3, 4, 6, 7, 9, 10, 11, 12, 15, 17, 18, X and Y. The majority of tumor samples showed aneuploidy for most chromosomes analyzed. The main chromosomal abnormality was loss of chromosomal material, predominantly of chromosomes 3 (28%), 6 (20%), 9 (26%), 10 (24%) and 18 (33%). Multiple deletions could be demonstrated more frequently in poorly differentiated carcinomas (88% G3-tumors with more than one deletion in contrast to 66% G2-tumors). The occurrence of multiple deletions may also correlate with progression in lymph node metastasis (66% in pN0-tumors vs. 85% in pN2-tumors), whereas the differences between the stages of primary tumor extension were not so obvious. Despite of a some-what disproportionate distribution of tumors in the different pT- and pN-stages and the rather low number of cases, our results suggest a relationship between the quantity of chromosomal underrepresentation, grade of differentiation and higher lymph node stage. Therefore, they underline the importance of chromosomal deletions as a possible additional prognostic marker in head and neck squamous cell carcinoma.