The genetic mutations underlying colon and rectal cancer are so similar
that these cancers should be classified as one disease, a study suggests. Researchers
analysed over 200 tumour samples and also identified genes that could serve as
targets for future drug treatments.
Dr Francis Collins, director of the National Institutes of Health which
funded the research, said that the team had revealed 'the true genetic
nature of colon and rectal cancers' and this was 'an important achievement in
our quest to understand the foundations of this disease'.
Scientists working with the
international Cancer Genome Atlas Network sequenced the exomes - the protein-coding
portions of all the genes in the genome - of the tumour samples. They were able
to reveal which genes and signalling pathways are often abnormal in colorectal
cancer and identified new genes which may be important in the cancer's
development, as well as confirming existing key players.
Such information may change
treatment strategies in colorectal cancer. For example, one of the genes, ERBB2, that the
researchers associated with colorectal cancer is also mutated in some types of
breast cancer. Patients with this type of breast cancer respond well to the
drug Herceptin and so this drug may be effective in colorectal cancer. Clinical trials would be needed to confirm this.
The study also highlighted genetic
factors that may influence the likelihood of surviving the disease. Earlier
research had already highlighted an association between a cancer's
aggressiveness and hypermutation - an abnormally high rate of genetic mutation.
After relating their findings to the according patient outcomes the authors
concluded that mutation rate might be a better indicator of survival than the
one currently used.
Speaking to The New York Times, Dr Charles Fuchs, a
gastrointestinal cancer expert at Harvard University and co-author on the study,
said that translation of the study's findings into clinical practice 'is going to take time, and it is
going to take effort', but added: 'I
don’t want to minimise the singular importance of this paper. It is