Tumors shed small pieces of genetic material and information that end up in the blood. These molecular signals in the blood can provide clues about the stage of a tumor sooner than, for example, a scan.
Scientists from the Princess Máxima Center for pediatric oncology analysed the blood of 99 children with the muscle tumor, rhabdomyosarcoma. They were looking for fragments of RNA from the tumor, molecules that send information from the genes.The scientists discovered 11 genes with high levels of RNA in the blood of children with rhabdomyosarcoma, but that were not or hardly present in the blood of healthy volunteers. This difference is important in order to select genes that can help clearly tell apart cancer cells from healthy cells. Their research was published this month in the journal Clinical Cancer Research, and was funded by KiKa.
To test whether the RNA blood test could provide clues about the prognosis, the researchers looked course of the children’s disease. ‘Children whose blood test picked up tumor RNA at diagnosis had a greater risk of their cancer coming back,’ says Nathalie Lak, PhD student in the Tytgat group and involved in the research. 36 percent of these children survived for five years without their cancer coming back, compared with 88 percent of children without tumor traces in the blood.
Children whose muscle tumor is in one place usually have a better prognosis than those whose cancer has spread. But children with a local tumor who did have tumor traces in the blood had a higher risk of the cancer coming back, the researchers found. On the other hand, children whose tumors had already spread, but who had no tumor RNA in the blood, had a better prognosis than expected.
Spotting high-risk cancer sooner
The new blood test also helped pick out children with an even more aggressive ‘ultra-high-risk’ form of rhabdomyosarcoma. In these children, the tumor had already spread at diagnosis, and the researchers also found tumor traces in the blood.
The results need to be confirmed in a larger group of patients, but the new blood test could in future help identify children with a high-risk form of the disease at an early stage.
Nathalie Lak: ‘The blood test we have developed could be a good addition to our toolkit for diagnosing high-risk rhabdomyosarcoma. This gives us a much more accurate picture of the severity of the disease. If we can already predict how aggressive the tumor is at the time of diagnosis, doctors could tailor treatment even better to the individual child.’