Cancer is widely accepted by many scientists as a disease related to aging. So, why do kids get it?
That’s the question motivating some exciting new scientific investigations — and even some preliminary but promising discoveries — at major cancer centers.
We often think of cancerous cells as good cells gone bad, healthy cells that one day went rogue and turned into a tumor. But cancer doesn’t emerge overnight. Researchers have demonstrated that most cancers stem from cells that mutated bit by bit over time. Any cell heading toward cancer has to undergo precise changes, sometimes accumulating them in specific sequence, to become malignant. It can take years, or even decades, for this unlikely chain of events to result in a tumor.
Now that we know a lot about the onset of cancer, the idea of pediatric cancer is even more perplexing. Many physicians and researchers are asking: How can something so slow to form occur in children, or even in embryos?
Childhood cancer is rare — around 15,000 kids in the U.S. are diagnosed with it each year, according to the U.S. Centers for Disease Control and Prevention. The most common forms of cancer in kids are leukemias and lymphomas, as well as brain and other central nervous system tumors. Sadly, cancer is the second-leading cause of death for children 14 or younger, after accidents. It’s not for lack of trying: the U.S. National Institutes of Health alone allocated about $545 million for pediatric cancer research this year.
Scientists want to know why these children are getting cancer. Understanding how an old person’s disease develops in kids could offer clues about how to predict, or maybe even prevent, pediatric cancers.
At Memorial Sloan Kettering Cancer Center’s research institute, biologist and pediatric oncologist Alex Kentsis stumbled across a human gene with previously unknown function that may shed light on the mystery. Known as PGBD5, the gene is highly active in cells found in childhood tumors. Research suggests the gene may be responsible for rearranging pieces of the genome — potentially creating mutations so massive that they leapfrog the slow-but-steady accumulation typically characteristic of cancer, creating genomic instability and other hallmarks of cancer formation almost immediately.
Kentsis and his team worked backward, first identifying these large mutations in many childhood cancers and tracing them back to the PGBD5 source. Tests in human cells and in mice showed that cells with the active PGBD5 gene could become cancerous, even when the gene activity was limited to a short period of time.
Other groups looking into pediatric cancers have confirmed these findings, according to Kentsis. One of the reasons it took until recently to understand the gene’s role in cancer development is that most genomic tools can’t detect the large mutations; only recent technology advances in generating accurate DNA sequencing data made it possible to see them.
So, what’s next? With this new target, scientists can embark on clinical trials to determine whether existing treatments or new medicines in development might be able to counteract the activity of this cancer-causing gene. They can also develop tests to detect the gene’s presence and determine which kids are at highest risk of getting cancer for enhanced screening and earlier detection. And, further down the road, new gene-editing techniques such as CRISPR might make it possible to snip out or turn off PGBD5 to prevent the gene from triggering cancer. Let’s hope for the best.