Temporal patterns of patient‐reported trismus and associated mouth‐opening distances in radiotherapy for head and neck cancer: A prospective cohort study

Objectives To identify temporal patterns of patient‐reported trismus during the first year post‐radiotherapy, and to study their associations with maximal interincisal opening distances ( MIO s). Design Single institution case series. Setting University hospital ENT clinic. Participants One hundred and ninety‐six subjects who received radiotherapy ( RT ) for head and neck cancer ( HNC ) with or without chemotherapy in 2007‐2012 to a total dose of 64.6/68 Gy in 38/34 fractions, respectively. All subjects were prospectively assessed for mouth‐opening ability (Gothenburg Trismus Questionnaire ( GTQ ), European Organization for Research and Treatment of Cancer quality of life Questionnaire (EORTC QLQ‐H&N35), and MIO ) pre‐ RT and at 3, 6 and 12 months after RT . Main outcome measures Correlations between temporally robust GTQ symptoms and MIO as given by Pearson's correlation coefficients ( P r ); temporally robust GTQ ‐symptom domains as given by factor analysis; rates of trismus with respect to baseline by risk ratios ( RR s). Results Four temporally robust domains were identified: Eating (3‐7 symptoms), Jaw (3‐7), Pain (2‐5) and Quality of Life ( QoL , 2‐5), and included 2‐3 persistent symptoms across all post‐ RT assessments. The median RR for a moderate/severe (>2/>3) cut‐off was the highest for Jaw (3.7/3.6) and QoL (3.2/2.9). The median P r between temporally robust symptoms and MIO post‐radiotherapy was 0.25‐0.35/0.34‐0.43/0.24‐0.31/0.34‐0.50 for Eating / Jaw / Pain / QoL , respectively. Conclusions Mouth‐opening distances in patients with HNC post‐ RT can be understood in terms of associated patient‐reported outcomes on trismus‐related difficulties. Our data suggest that a reduction in MIO can be expected as patients communicate their mouth‐opening status to interfere with private/social life, a clinical warning signal for emerging or worsening trismus as patients are being followed after RT .