One-sided

Top Line: At what point are we going to feel comfortable treating unilaterally for localized tonsil cancer

The Study: This meta-analysis of 17 studies (mostly retrospective) including 1487 patients receiving unilateral radiation reports a pooled rate of contralateral neck failure of only 1.9%. This is because most patients, as expected, had small tumors. Contralateral neck failure was strongly associated with T stage and was much higher for those who had more advanced tumors (making it difficult to imagine how they were truly well lateralized): 1.3% for T1, 3% for T2, 11% for T3, and 16% for T4. This did not appear to be the case with increasing nodal stage. When compared to other patients from the studies who received bilateral treatment, unilateral treatment was associated with a statistically higher risk of contralateral neck failure (OR 1.29) while it slashed combined risk of grade 3+ xerostomia and/or feeding tube use from 13% to 0.9%. Note this difference in toxicity appears to be in contradiction to very low rates of patient-reported outcomes for bilateral versus unilateral RT.

TBL: For patients with small, well-lateralized tonsil cancers, this meta-analysis suggests the absolute risk of contralateral neck failure is low. However, this rate is statistically higher than with bilateral neck RT.