Statistical Study Characterizes Patterns of Cancer Chromosome Aneuploidy

A large statistical study of cancer genome karyotypes has revealed a pattern linking gain or loss of chromosomes (aneuploidy) in more than 60 different classes of the disease.

Chromosomal aneuploidy is the most common abnormality in cancer. While certain aberrations, most commonly translocations, are known to be strongly associated with specific cancers and contribute to their formation, most aberrations appear to be nonspecific and arbitrary, and do not have a clear effect. The understanding of chromosomal aneuploidy and its role in tumorigenesis is a fundamental open problem in cancer biology.

Loss or gain of chromosomes is usual detrimental or fatal to an organism. Yet, most cancers thrive with bizarre alterations of chromosome number. To understand this phenomenon better, investigators at Tel Aviv University (Israel) systematically studied the characteristics of chromosomal aberrations in over 15,000 cancer karyotypes over 62 cancer classes.

Results published in the June 29, 2011, online edition of the journal Genome Biology revealed a very high co-occurrence rate of chromosome gains with other chromosome gains, and of losses with losses. Gains and losses rarely showed significant co-occurrence. This finding was consistent across cancer classes and was confirmed on an independent comparative genomic hybridization dataset of cancer samples.

“In cancer, there are many cases of extra or missing chromosomes. Yet cancer cells thrive more effectively than other cells,” said senior author Dr. Ron Shamir, professor of computer science at the University of Tel Aviv. “Hopefully future investigation into these chromosomal aberrations will give researchers more clues into why something that is so detrimental to our healthy development is so beneficial to this disease. Cancer is the result of sequences of events, each causing the genome to become more mutated, mixed, and duplicated. Tracking these changes could aid our understanding of the driving forces of cancer's progress.”

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