The Use of Pre-Chemoradiotherapy Total Masseter Muscle Volume as a Novel Predictor of Radiation-Induced Trismus in Locally Advanced Nasopharyngeal Carcinoma Patients.

BACKGROUND: We sought to determine whether pretreatment total masseter muscle volume (TMMV) measures can predict radiation-induced trismus (RIT) in patients with locally advanced nasopharyngeal carcinoma (LA-NPC) receiving concurrent chemoradiotherapy (C-CRT). METHODS: We retrospectively reviewed the medical records of LA-NPC patients who received C-CRT and had pretreatment maximum mouth openings (MMO) greater than 35 mm. MMO of 35 mm or less after C-CRT were considered RIT. We employed receiver operating characteristic (ROC) curve analysis to explore the correlation between pre-treatment TMMV readings and RIT status. RESULTS: Out of the 112 eligible patients, 22.0% of them received a diagnosis of RIT after C-CRT. The optimal TMMV cutoff that was significantly linked to post-C-CRT RIT rates was determined to be 35.0 cc [area under the curve: 79.5%; sensitivity: 75.0%; and specificity: 78.6%; Youden index: 0.536] in the ROC curve analysis. The incidence of RIT was significantly higher in patients with TMMV ≤ 5.0 cc than in those with TMMV > 35.0 cc [51.2% vs. 8.7%; Odds ratio: 6.79; p < 0.001]. A multivariate logistic regression analysis revealed that pre-C-CRT MMO ≤ 41.6 mm (p = 0.001), mean masticatory apparatus dose V56.5 ≥ 34% group (p = 0.002), and TMMV ≤ 35 cc were the independent predictors of significantly elevated rates of RIT. CONCLUSION: The presence of a smaller pretreatment TMMV is a reliable and independent novel biological marker that can confidently predict higher RIT rates in LA-NPC patients who receive C-CRT.

Worth of pan-immune-inflammation value in trismus prediction after concurrent chemoradiotherapy for nasopharyngeal carcinomas.

OBJECTIVE: Radiation-induced trismus (RIT), one of the rare but serious side effects of concurrent chemoradiotherapy (C-CRT), is difficult to predict with high accuracy. We aimed to examine whether the pretreatment pan-immune-inflammation value (PIV) measures predict RIT in patients with locally advanced nasopharyngeal carcinoma (LA-NPC) receiving C-CRT. METHODS: Data of patients with LA-NPC who underwent C-CRT and had maximum mouth openings (MMO) > 35 mm were reviewed. Any MMO of 35 mm or less after C-CRT was considered RIT. All PIV values were computed using the complete blood count test results: PIV = (Platelets × Monocytes × Neutrophils) ÷ Lymphocytes. The receiver operating characteristic analysis was employed to dissect a possible association between pre-treatment PIV readings and RIT status. Confounding variables were tested for their independent relationship with the RIT rates using logistic regression analysis. RESULTS: The research comprised 223 participants, and RIT was diagnosed in 46 (20.6%) at a median time from C-CRT to RIT of 10 months (range: 5-18 months). Pre-C-CRT PIV levels and RIT rates were analyzed using receiver operating characteristic curve analysis, with 830 being the optimal cutoff (area under the curve: 92.1%; sensitivity: 87.5%; specificity: 85.5%; Youden index: 0.730). RIT was significantly more prevalent in the PIV > 830 cohort than its PIV ≤ 830 counterpart (60.3% vs. 5%; hazard ratio 5.79; P < 0.001). Multivariate logistic regression analysis revealed that advanced T-stage (P = 0.004), masticatory apparatus dose V58Gy≥%32 (P = 0.003), and PIV > 830 (P < 0.001) were independently linked with significantly elevated rates of RIT. CONCLUSION: The presence of elevated pre-C-CRT PIV is a unique biological marker that independently predicts increased RIT rates in LA-NPC undergoing C-CRT.

Decreased Rates of Radiation-induced Trismus and Lowered Mastication Structure Doses in Patients Treated for Head and Neck Cancer During the Last Two Decades.

AIMS: To investigate how absorbed doses to mastication structures in modern radiotherapy (RT) technique for head and neck cancer (HNC) compared with earlier RT techniques and with published trismus tolerance doses. To compare the incidence of radiation-induced trismus by earlier and newer RT techniques. MATERIALS AND METHODS: This study investigated two HNC patient cohorts treated with RT in 2007-2012 (three-dimensional conformal radiotherapy [3DCRT] and/or intensity-modulated radiotherapy [IMRT]; n =121 [Cohort 1]) and 2017-2020 (volumetric-modulated arc therapy [VMAT]; n =124 [Cohort 2]). All patients underwent RT without mastication structure-sparing intent, had normal mouth-opening ability before RT, and were prospectively assessed. Trismus was defined as the maximal interincisal opening ≤35 mm at any follow-up (3-, 6-, and 12-months post-RT). The temporomandibular joints (TMJs), masseter, and medial/lateral pterygoid muscles were delineated on the planning CT:s. Mean doses were compared between cohorts, and evaluated with respect to published trismus tolerance doses. P values ≤ 0.05 indicated statistical significance. RESULTS: Within 12 months post RT, 74/121 (61%) of patients in Cohort 1 had experienced trismus compared to 11/124 (9%) in Cohort 2. Averaged mean doses (±S.D.) for the masseter muscles were 35.2±8.3 Gy in Cohort 1 and 20.2±8.7 Gy in Cohort 2 (P <0.001). Corresponding numbers were 19.1±16.2 and 4.3±4.3 Gy for the TMJs, 53.7±10.1 and 40.2±16.8 Gy for the medial pterygoid muscles, and 29.2±18.7 and 9.2±8.4 Gy for the lateral pterygoid muscles (all P <0.001). Masseter muscle doses were below tolerance doses in 23% of patients in Cohort 1 compared with 90% in Cohort 2. The corresponding numbers were 52% and 96% for the TMJs, 8% and 36% for the medial pterygoid muscles and 72% and 100% for the lateral pterygoid muscles. CONCLUSION: Mastication structure mean doses by more recent RT techniques were generally below proposed tolerance doses, with dose reductions of 10-20 Gy compared with earlier techniques. Modern RT without mastication-structure-sparing intent resulted in below 10% of HNC patients experiencing trismus compared with 60% treated with earlier techniques.