People whose head and neck cancers test positive for the human papilloma virus are known to respond more favorably to radiation therapy than those whose cancers are HPV-negative, but an explanation for these differences has remained elusive.
Now, UCLA scientists have shown for the first time that radiation treatment transforms cancer cells into head and neck cancer stem cells — which are known to be resistant to radiation therapy — more effectively when the cancer tests negative for HPV. These findings shed light on why some head and neck cancers fare much worse after radiation therapy despite optimum treatment regimens.
Led by UCLA Jonsson Comprehensive Cancer Center members Dr. Erina Vlashi and Dr. Frank Pajonk, the study showed that the non-stem cancer cells that survived radiation therapy had the ability to convert into cancer stem cells, which have shown to be more resistant to radiation treatment. The process, called “radiation-induced conversion,” happened at a higher frequency in HPV-negative head and neck cancers, providing a clinically relevant explanation for the differences in response to radiation therapy.
The team reviewed 162 head and neck squamous carcinomas patients over a two-year period, and confirmed that their outcomes were correlated with their HPV status.
The study built on Vlashi and Pajonk’s previous research in breast cancer.
While radiation therapy may have some negative consequences, it remains an indispensable treatment for cancer patients. Further studies are currently underway to identify drugs that can interfere with radiation-induced conversion, said Vlashi.
The scientists hope this research will lead to a new type of combination treatment to improve the response of head and neck tumor cells to radiation therapy.
Read the full news release.