Genetic Variants Found in Different Cancers
Unrelated Cancers are More Linked Than Scientists Thought
Feb 6, 2009
It is already well known that certain forms, or mutations, of particular genes may confer a susceptibility to a specific cancer. Many cancers may have components of inheritance that are due to common genetic mutations or variants. However, identifying these variants has been a challenge. New evidence coming from genome-wide sequencing studies is revealing unique genetic mutations involved in different cancers.
A Common Genetic Variant Involved in Prostate, Ovarian and Breast Cancers
In November 2008, British researchers, Dr Paul Pharoah and colleagues, from University of Cambridge, analyzed 12 genetic mutations, more properly called variants, previously identified as risk factors of prostate cancer. They studied these variants in the context of ovarian, breast and colorectal cancers.
In this study the researchers showed that one genetic variant (rs5945619) in the chromosome X, was associated with ovarian and breast cancers in addition to prostate cancer. This observation supports the fact that a common genetic basis for prostate, ovarian and breast cancer may exist. This study, entitled “Association study of prostate cancer susceptibility variants with risks of invasive ovarian, breast and colorectal cancer” was published in the scientific journal Clinical Cancer Research (Cancer Res 2008;68(21):8837-42) and discussed in the article, Common Genetic Forms for Different Cancers.
A Common Genetic Variant Involved in Lung, Urinary Bladder, Prostate and Cervix Cancers
More recently, another group of scientists from the pharmaceutical company deCODE Genetics in Iceland, lead by Kari Stefanson and Thorunn Rafnar, tested in seventeen different cancers the presence of the genetic variant named rs401681[C] located in the chromosome 5, between a gene involved in chemotherapy treatment response (CLPTM1L) and a gene named TERT. Their study entitled “Sequence variants at the TERT-CLPTM1L locus associate with many cancer types” was published in the prestigious scientific journal Nature Genetics (Feb 2009, vol41, pp221-227).
The researchers found the genetic variant rs401681[C] confers a risk to basal cell carcinoma in addition to prostate, urinary bladder, lung and cervix cancers. They did not observe any association with kidney, stomach, thyroid, breast, ovary, pancreas, lymphoma or multiple myeloma. Since the risk related to the cancers carrying the genetic variant rs401681[C] has been linked to some degree with environmental factors, the researchers suppose that rs401681[C] may predispose to cancer through response to environmental factors.
Prostate and Pancreatic Cancers Linked to Breast Cancer Gene BRCA2
Two other recent studies, released in January 2009, also revealed common genetic risks between breast cancer and aggressive prostate cancer. Researchers found that mutations of BRCA 1 and BRCA 2, two known genetic risks of ovarian and breast cancers are also associated to prostate and pancreatic cancers.
Interestingly enough, Ashkenazi Jewish patients with aggressive tumours were 3 times more likely to carry the BRCA2 gene mutation than were men in the control group. This study entitled “Associations of High-Grade Prostate Cancer with BRCA1 and BRCA2 Founder Mutations” was published in Clinical Cancer Research Journal (2009 Feb 1;15(3):1112-20). On the other hand Dr Robson and colleagues from the Memorial Sloan-Kettering Cancer Center, found that BRCA2 mutations in Ashkenazi men are associated with pancreatic adenocarcinoma. The study entitled “BRCA germline mutations in Jewish patients with pancreatic adenocarcinoma” was published in Journal of Clinical Oncology (2009 Jan 20;27(3):433-8).
Altogether these studies reveal that more common genetic factors are involved in different cancer types. This also supports the fact that common genetic basis for different cancers and that cancer patients are more likely to have a first-degree relative with another cancer that was previously though unrelated.
 |
