The role of chromosomes in the characterisation of human neoplasms

Abstract

Observations reported in the literature, since 1959, have been assessed and analysed for chromosome number per cell (ploidy levels) and karyotype (number of chromosomes per classification group, structure and DNA content of individual chromosomes). Measurements of chromosome size are presented, to show how the genetical balance of chromosomal types within a karyotype can be determined in pseudodiploid and aneuploid cells. These findings are discussed in relation to the role of chromosome anomalies in cell metabolism, malignant transformation and Boveri's theory that chromosome anomalies cause cancer. Objections to Boveri's Theory arise from the occurrence of (a) certain aneuploid pathological conditions and cell lines that are non-malignant, and (b) diploid primary and secondary malignant neoplasms with apparently normal karyotype. However, studies on families have indicated that syndromes due to chromosome anomalies may predispose cells for malignant transformation because of their metabolic instability; and the possibility remains that apparently diploid neoplasms may be pseudodiploid (and await further techniques for their detection). Evidently, chromosome anomalies have a metabolic effect in neoplasms and are of considerable importance in aiding the progression of neoplasms towards greater malignancy. The selective advantage of cell variants results in the evolution of characteristic ploidy levels of tumours at different sites. Chromosome studies may aid the diagnosis of malignancy in some neoplasms, where striking changes in the chromosome constitution is directly associated with their capacity for invasion.