Radiotherapy Planning for Nasopharyngeal Carcinoma After Induction Chemotherapy: A Systematic Review to Inform...

Induction chemotherapy (ICT) followed by concurrent chemoradiotherapy is a standard of care in locoregionally advanced nasopharyngeal carcinoma (LA-NPC). However, there is a lack of consensus on appropriate radiotherapy (RT) target volumes and prescriptions after ICT. We systematically reviewed the literature to inform a planned international consensus guideline development.

A scoping review was done to define the areas of significant practice differences, followed by a systematic review. The reviews were conducted by a Steering Committee (SC) and an Evidence Review Committee (ERC) consisting of radiation oncologists with expertise in treating NPC.

The scoping review revealed significant practice differences on (1) optimal timing for post-ICT RT, (2) ideal imaging modalities for RT target delineation, (3) RT dose prescription and fractionation, and (4) RT target volume delineation. The systematic review found no specific recommendations on optimal timing for post-ICT RT and optimal imaging modalities. Regarding dose prescription, current guidelines advocate including two or three dose levels. Differences in post-induction target volume delineation were found. The data show that volume reduction may be possible without compromising oncologic outcomes and may improve quality of life.

There is a lack of evidence and guidelines on post-ICT RT timing and optimal imaging modalities. Guidelines on post-ICT target volumes and dose levels differ significantly; published evidence from clinical trials is limited. Considering this lack of consensus after ICT in LA-NPC, international consensus guidelines among experts from endemic regions are needed and may help harmonize practices.