Impact of fraction size on locally advanced oropharyngeal and nasopharyngeal cancers treated with chemoradiation

- Compared survival outcomes for chemoradiation using 1.8, 2 or 2.12 Gy fraction sizes.
- Survival differences assessed in entire cohort and in a propensity matched subset.
- Compared to 1.8 and 2 Gy fractions sizes, 2.12 Gy associated with improved survival.
- Slightly hypofractionated regimens may benefit certain head and neck cancers.

ObjectivesAlthough chemoradiation regimens have used various fraction sizes, it remains unclear how differences in fraction size impact outcomes.Materials and methodsUsing the National Cancer Database, we identified patients with nasopharynx or oropharynx cancers treated between 2004 and 2012 with chemoradiation using fraction sizes of 1.8 Gy (n = 1612), 2 Gy (n = 8092) or 2.12 Gy (n = 1660). Comparisons between fraction sizes were made in the entire cohort and in a propensity matched cohort.ResultsMedian follow-up was 38.1 m. Patients receiving 2.12 Gy per fraction were more likely to be treated from 2007 to 2012, to be treated at an academic center, to have T3-T4 tumors and to have oropharyngeal primaries. The 3 year overall survival for patients treated with 1.8 Gy, 2 Gy and 2.12 Gy fraction sizes was 72.9%, 77.8% and 83.3%, respectively (P < 0.0001). 2.12 Gy fraction size was associated with improved survival in patients with nasopharynx cancer (P = 0.03), base of tongue cancer (P < 0.0001) and tonsil cancer (P = 0.0002). On multivariate analysis, improved survival was associated with 2.12 Gy fraction sizes compared to 2 Gy (HR 1.23, 95% CI 1.09-1.40, P = 0.001) or 1.8 Gy (HR 1.36, 95% CI 1.17-1.58; P < 0.0001) fractions sizes.ConclusionChemoradiation regimens using 2.12 Gy fraction sizes likely have a potential advantage in select nasopharynx and oropharynx cancer patients based on age, treatment facility and radiotherapy technique. However, it remains unclear if this survival advantage reflected improved disease control due to lack of locoregional control data.