What is the significance of grade in OPSCC?

Multiple groups have found an association between the impact of fractionation schedule on outcome and tumor differentiation using high quality prospective data (Eriksen et al., PMID 14751528, Bentzen et al., PMID 16110017, Lyhne et al., PMID 26255764). Well-diff and to a lesser extent moderate-diff is associated with benefit from accelerated fractionation whereas poorly differentiated is not. Likewise, treatment with a split course is associated with detriment for well-diff tumors but not poorly diff (Hansen et al., PMID 9165136). These data are from multiple subsites and are not specific to Opx. 

1. Fractionation schedule for the elderly patient in the absence of systemic therapy. We know that benefits of treatment intensification either as concomitant systemic therapy or altered fractionation are diminished or even absent as frailty increases. For the older, semi-frail patient who is systemic-therapy ineligible, definitive treatment with conventionally fractionated radiation is reasonable when SCC is poorly differentiated. 
2. Management of the unplanned treatment interruption. Treatment interruptions can be detrimental yet sometimes unavoidable. For well and moderately differentiated tumors, mountains should be moved to keep treatment on schedule and I compensate any interruptions with BID or weekend treatments to finish as planned. For patients with poorly diff disease, we still aim to stay on schedule but understanding this data allows more flexibility for course corrections.

They are mostly poorly differentiated. I pay attention to P16 status, not so much grade.