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Headline: De-escalation of definitive chemoradiation to 60 Gy for p16(+) oropharyngeal cancer leads to acceptable (enough) local tumor control at 2 years.
The Study: Having finally stepped off the hampster wheel of systemic therapy de-escalation, we can now turn to solid clinical data on outcomes with radiation de-escalation with reporting of the phase 2 NRG-HN002. It enrolled 306 patients with low-risk oropharyngeal squamous cell carcinoma (SCC) who all received 2 Gy x 30 = 60 Gy with a goal of achieving “acceptable” rates of progression-free survival (PFS) compared with historical standards, or >85%. What’s intrinsically better about this 10 Gy cushion? The hope was better swallowing at one year, or a mean composite score >60 on a validated dysphagia inventory. Here’s where you need to pay attention: while enrollees were randomized to +/- concurrent weakly cisplatin, this was mostly to buy two studies for the price of one IRB approval. Rather than compare the arms to each other, two levels of de-escalation could each be compared to historical controls as above. Ok, now we can cue the drum roll. Among 157 patients receiving definitive chemoradiation to 60 Gy, PFS at 2 years was 91%, meeting the a priori threshold of “acceptable.” Anyone want to wager how the patients did without chemo? Unacceptably. Their PFS was 88% with a confidence interval falling below the threshold. In better news, both arms achieved soaring mean composite swallowing scores of 82-85.
TBL: Comparing a definitive chemoradiation regimen—de-escalated to 60 Gy but with concurrent cisplatin—to the current standard of 70 Gy in a large phase 3 setting to achieve better swallowing function appears justified. | Yom, ASTRO 2019