I spent many years as a health reporter for a wire service writing stories about scientists finding “a gene for” one disease or another. In those early days of the genomics revolution it was exciting any time someone was able to associate a particular genetic region with cancer, heart disease or whatever.
These days, the rate of discovery has accelerated. As the story below shows, enormous international collaborations are now capable of finding dozens of genetic regions that are associated with an increased risk of certain cancers. Although each of these regions only contributes a small fraction of the risk of cancer according to the researchers’ statistical analysis, they say it’s possible that any one of them could prove to be an effective treatment for cancer, just as statins have proved to be an effective cholesterol treatment.
Still, the trick with writing these stories remains the same as it did back in the days of single-gene discovery news: of themselves, these discoveries do not improve treatment, screening or prevention of cancer. They only point to potential future approaches, which makes it that much harder to write a compelling story. Probably the real story to write–one that would take a lot more space–is how we are creeping toward the day when we have cancer treatments that are as effective as antibiotics can be for infections. In those terms, cancer treatment is still in the pre-antibiotic era.
Study unravels genetic jigsaw of hormone cancers
Their findings, published in 13 papers, roughly double the number of genetic regions that scientists know to be associated with these cancers, which together affect more than 2.5 million people each year. Crucially, many of the genes identified in the study appear to affect more than one type of cancer. This means it may be possible to develop treatments that will combat several different cancers, says cancer geneticist John Witte from theUniversity of California, San Francisco. “While the current findings do not immediately change the clinical treatment for any of these cancers, they do get us closer to this ultimate goal,” says Witte, who wrote a commentary on the results this week in the journal Nature Genetics . “Now we have a very large number of genetic variants clearly associated with risk of cancers, and a number of these impact more than one cancer. These findings may help clarify the most optimal screening, biology, and treatment for different cancers.”
The COGS researchers began by analysing data from multiple earlier ‘genome-wide association studies’ that had linked particular genetic variations with cancer risk in tens of thousands of patients. They then used 211,000 of those promising genetic markers to design a custom genotyping array – a tool for identifying the presence of particular genetic sequences – and used it to test samples from more than 200,000 cancer patients and controls. The findings include 49 new genetic susceptibility regions for breast cancer, 26 for prostate cancer and eight for ovarian cancer. The results also include susceptibility genes for the cancers in specific populations, such as individuals with BRCA1 or BRCA2 mutations. The exact functions of most of the genes identified remains to be uncovered, but already some important trends have emerged that could lead to improved treatments. Among the most notable findings was the genetic overlap among cancers. Such overlaps point directly at the mechanisms that initiate the cancer-forming process in these three hormone-related cancers. “This is one of the most exciting aspects of this work,” says Witte. If those mechanisms are shared among cancers, treatments for one cancer might also prove successful for other cancers as well. “Instead of categorising cancers as distinct diseases, we may have great research and treatment success in studying the similarities across cancers,” he says. Dr Georgia Chevenix-Trench, from the Queensland Institute of Medical Research, agrees. “It’s important to note that any one of these regions could become a new drug target that is effective for either prevention or treatment of these common cancers,” says Chevenix-Trench, one of several Australian researchers involved in the project. And the findings are just the tip of the iceberg, she says. “In breast cancer, for example there is good evidence that there may be up to 10,000 loci that confer risk that the study wasn’t statistically powerful enough to study.”
The results may also help the fight against cancer by improving screening, say the study authors Researchers are already working on ways to stratify the cancer risk of individuals based on inherited genetic variants. Such tests might first be used in people who are already at high risk of disease, such as women for example who have BRCA1 or BRCA2 mutations. In years to come they could be used more widely. “It’s always hard to guess timelines but I would think that within five to 10 years it might be being used commonly,” says Dr Paul Pharoah, lead author of one of the ovarian cancer studies from the University of Cambridge. Full details of all the papers can be found on the Nature website.