Adaptive radiotherapy for head and neck cancer: Are we ready to put it into routine clinical practice?

Patients with head and neck cancer who are treated with radiotherapy often have significant weight loss or tumor regression during treatment. Adaptive radiotherapy refers to acquiring new imaging during treatment and changing the parameters of the radiation plan based on the new imaging findings. There is accumulating evidence that adaptive radiotherapy can reduce toxicity and improve tumor control, though it is not yet known which patients benefit most. For patients with profound tumor regression, there is also uncertainty about how much to shrink the region receiving high radiation dose. Another form of adaptive radiotherapy uses advanced imaging such as positron emission tomography to visualize changes in tumor biology during treatment. Tumor regions that are thought to be more radioresistant can then be treated to a higher radiation dose, and vice-versa. Studies employing this strategy to boost radiation dose have shown a high rate of late toxicity, specifically the development of persistent mucosal ulcers. Therefore, this sort of adaptive radiotherapy is currently confined to the research setting.