HPV-positive T1-3N0-2c patients have a low DM risk, but N2c patients from this group have a reduced DC when treated with RT alone and seem less suited for deintensification strategies that omit chemotherapy.

An RPA-based TNM stage grouping (stage I/II/III: T1-3N0-N2b/T1-3N2c/T4 or N3, with M1 as stage IV) is proposed for HPV-related OPC as a result of significantly improved survival prediction compared with the seventh edition TNM, and prognostication is further improved by an RPA-based prognostic grouping within the American Joint Committee on Cancer/Union for International Cancer Control TNM framework for HPV-related OPC.

Abstract. Peculiar atmospheric radar echoes from the high-latitude summer mesosphere have spurred much research in recent years. The radar data (taken on frequency bands ranging from 2 to 1290 MHz) have been supplemented by measurements from an increasing arsenal of in situ (rocket borne) and remote sensing (satellites and lidars) instruments. Theories to explain these polar mesosphere summer echoes (PMSEs) have also proliferated. Although each theory is distinct and fundamentally different, they all share the feature of being dependent on the existence of electrically charged aerosols. It is therefore natural to assume that PMSEs are intimately linked to the other fascinating phenomenon of the cold summer mesopause, noctilucent clouds (NLCs), which are simply ice aerosols that are large enough to be seen by the naked eye. In this paper we critically examine both the data collected and the theories proposed, with a special focus on the relationship between PMSEs and NLCs.

Submicron aerosols, as evidenced by the occurrence of polar mesospheric and noctilucent clouds, exist at heights from which polar mesosphere summer echoes (PMSE) are observed. We investigate the role of positively and negatively charged aerosols in the scattering processes proposed in the literature. These aerosols, if charged substantially, can account for the remarkably high radar reflectivity at both VHF and UHF by raising the electron Schmidt number through the ambipolar effect. A positively charged component may be responsible for enhanced UHF radar scatter by increasing the incoherent scatter power through a dressed dust effect, although such a process is not realistic as an explanation for VHF scatter during PMSE. Such an enhanced UHF scatter will be associated with extremely narrow backscatter spectra. We propose a model in which both negatively and positively charged aerosols are present to explain both the radar properties and the rocket probe observations of charged particle depletions. Finally, we point out that the Poker Flat 50-MHz long-term data, which contrary to accepted dynamical theory show average downward velocities in the summertime upper mesosphere, can be attributed to the fall speed of the aerosols responsible for PMSE.