“As radiation oncologists, we have pushed some important envelopes to try to mitigate long-term toxicity,” said David Raben, MD, Professor of Radiation Oncology at the University of Colorado Cancer Center, Aurora, Colorado.

David Raben, MD

“We’ve been able to utilize intensity-modulated radiation techniques to spare critical swallowing-related structures, salivary tissue including the submandibular glands, and in our institution, even thyroid tissue. Yet, we still treat large volumes in the head and neck to cover involved and uninvolved lymph node basins to ensure we eradicate microscopic disease. Across the United States and Europe, we are exploring ways to reduce radiation dose for HPV [human papillomavirus]-positive cancers,” he said.

“Despite the controversies surrounding the use of induction chemotherapy prior to radiation, Melotek and colleagues explored whether induction chemotherapy could in fact allow reduction of radiation volumes in an effort to reduce long-term toxicities. This is a bold move, but I think it’s time to explore these possibilities and this is a step forward,” he commented.

“I will say, however, that it took a very big chemoradiation stick to get to ~41% response and subsequent volume reduction. Combining induction chemotherapy followed by a well-established University of Chicago regimen of accelerated, hyperfractionated radiation combined with triple chemotherapy (non–cisplatin based) resulted in excellent survival outcomes, even with the HPV-negative cohort,” he continued, “but the acute toxicies are not inconsequential. Importantly, all failures above the clavicles were infield in responders, so this is a good start. It suggests that this is a potentially safe strategy.”

Dr. Raben told The ASCO Post: “This is one of the first studies to actually look at reducing radiation volumes to areas of gross disease only for responders; however, one could speculate that patients with HPV-positive tumors might not need this type of approach and could be treated with reduced chemotherapy intensification as well as a reduced radiation dose. It will be interesting to see if this approach is applicable for patients using immunotherapy based strategies in the future—perhaps radiation will become the firestarter rather than the fire.

“I believe we can continue to refine chemotherapy and radiation delivery and dose and look to reduce acute toxicities as well as late toxicities—aggressive yet elegant. Needless to say, a randomized study would be important to look at radiation volume reduction carefully.” ■

Disclosure: Dr. Raben is on sabbatical and consulting for Astra Zeneca.