Radiation treatment can transform head and neck cancer cells that survive the treatment into cancer stem cells that are resistant to radiation therapy, and this transformation is more prevalent when the cancer is human papilloma virus (HPV)-negative.1
More favorable responses to radiation therapy have been found for HPV-positive head and neck cancers compared with cases of HPV-negative disease. This new study helps to explain why some patients with head and neck cancers fair much worse after radiation therapy despite optimum treatment regimens.
The study found that non-cancer stem cells that survived radiation therapy could convert to cancer stem cells. Cancer stem cells are known to be more resistant to radiation treatment. This conversion process was named radiation-induced conversion, and it happened at a higher rate in HPV-negative cancers than in HPV-positive cancers.
This study examined records from 162 patients with head and neck squamous cell carcinoma (HNSCC) and correlated their outcomes with their HPV status. The researchers then used a panel of HNSCC cells lines, some HPV-positive and some HPV-negative, and looked for cancer stem cells. Non-cancer stem cells from the cell lines were treated with different doses of radiation, and the researchers investigated how non-cancer stem cells changed to cancer stem cells.
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. Though radiation therapy can have unwanted consequences, its role in treating HNSCC is indispensable. Studies are underway to identify drugs that can interfere with the radiation-induced conversion.
1. Vlashi E, Chen AM, Boyrie S, et al. Radiation-induced dedifferentiation of head and neck cancer cells into cancer stem cells depends on HPV status. [published online ahead of print January 13, 2016]. Int J Radiat Oncol Biol Phys. doi:10.1016/j.ijrobp.2016.01.005.