Differences between Tumors of Younger and Older Colorectal Cancer Patients

Cases of colorectal cancers are on the rise in younger people. Doctors are of the opinion that some hereditary factors do play a role in its onset, but in majority of cases today it occurs spontaneously. Recent researches have led to the discovery that tumours in younger colorectal cancer patients could be molecularly distinct from those of older patients. These differences are related to the way genes are switched on and off (epigenetics) in the tumors of the younger patients. Such a discovery may lead to better treatment options tailored specifically to a younger age group, they say.

Colon Cancer

The results of the study will be presented to the 2015 European Cancer Congress by Dr. Andrea Cercek, an Assistant Attending Physician at the Memorial Sloan Kettering Cancer Center, and Assistant Professor of Medicine at Weill Cornell Medical Center, New York, USA. She is going to go over the details of her team’s analysis of genetic mutations in tumours from 126 patients under the age of 50 and 368 aged 50 and over. She says that it was interesting to find that there is a different frequency of mutation of genes known to be cancer-causing in the different age groups.

The tumours from the two groups of CRC patients were analysed “ one group received treatment at Memorial Sloan Kettering and the other group were from The Cancer Genome Atlas – a project run by the US National Cancer Institute, with the goal to catalogue cancer-causing genetic mutations.

In order to look for gene mutations and other changes in the DNA which affects gene expression and methylation, genomic sequencing techniques were used. Those patients who had a very large number of mutations or had microsatellite instability issues were excluded. Dr. Cercek explained that in cancer both under (hypo) and over (hyper) methylation of genes are found. In the early onset group it was found that 154 genes were under-methylated. It was also seen that as age increased there was an increase in methylation in younger patients. This increase was far greater than what would occur naturally in normal tissue. This finding makes the researchers optimistic that tailored treatment can be designed to prevent or to improve the outcomes for the specific age group.

The Surveillance, Epidemiology, and End Result Registries (SEER), the agency that collects and collates cancer statistics on behalf of the US National Cancer Institute have revealed that there has been a continuous increase in CRC cases in younger people, at the rate of 1.5% per year in men and 1.6% per year in women during the period 1992-2011. Younger patients with CRC tend to be diagnosed later, when their disease is at a more advanced stage and therefore, more difficult to treat. The reason for this is a lack of awareness of symptoms in patients as well as doctors. Also, there is a tendency to attribute those symptoms to other causes.

Dr. Cercek opined that raising awareness of the increasing frequency of younger-onset CRC among doctors is very important. Even though there is no other difference in the therapies used it is seen that younger CRC patients are treated relatively more aggressively. The recent finding by the researchers is of significance so that they are able to develop better therapies for younger people, and improve their overall survival as well as their quality of life. Further research for identifying specific genetic patterns in CRC tumours in younger patients can lead to better treatment options.

Professor Peter Naredi, the ECCO scientific co-chair of the Congress, who was not a part of the research said that it is important to identify younger persons with a higher risk of CRC, and Dr. Cercek’s epigenetic analyses are an important step towards this.

References

https://medicalxpress.com/news/2015-09-differences-tumors-younger-older-colorectal.html

https://www.eurekalert.org/pub_releases/2015-09/eeco-dbt092415.php