Clinical results of proton therapy reirradiation for recurrent nasopharyngeal carcinoma.

Background and purpose: Recurrent nasopharyngeal carcinoma (NPC) has limited curative treatment options. Reirradiation is the only potential definitive treatment in advanced stages at a cost of substantial severe and often life-threatening toxicity. Proton therapy (PT) reduces irradiated volume compared with X-ray radiotherapy and could be advantageous in terms of safety and efficacy in a population of heavily pretreated patients. We report the retrospective results of PT reirradiation in recurrent NPC patients treated at our Institution Methods: All recurrent NPC patients treated since the beginning of clinical activity entered the present analysis. Clinical target volume consisted of Gross Tumor volume plus a patient-specific margin depending on disease behavior, tumor location, proximity of organs at risk, previous radiation dose. No elective nodal irradiation was performed. Active scanning technique with the use of Single Field Optimization (SFO) or Multifield Optimization (MFO) was adopted. Cumulative X-ray -PT doses were calculated for all patients using a dose accumulation tool since 2016. Treatment toxicity was retrospectively collected. Results: Between February 2015, and October 2018, 17 recurrent NPC patients were treated. Median follow-up (FUP) was 10 months (range 2-41). Median PT reirradiation dose was 60 Gy RBE (range 30.6-66). The majority of patients (53%) underwent concomitant chemotherapy. Acute toxicity was low with no ≥ G3 adverse events. Late events ≥ G3 occurred in 23.5% of patients. Most frequent late toxicity was hearing impairment (17,6%). G2 soft tissue necrosis occurred in two patients. Fatal bleeding of uncertain cause (either tumor recurrence or G5 carotid blowout) occurred in one patient. Kaplan-Meier 18 months Overall Survival (OS) and Local control (LC) rates were 54.4% and 66.6%, respectively. Conclusions: Our initial results with the use of modern PT for reirradiation of recurrent NPC patients are encouraging. Favorable LC and OS rates were obtained at the cost of acceptable severe late toxicity.

Carbon ion therapy (C12) for high-grade malignant salivary gland tumors (MSGTs) of the head and neck: do non-ACCs profit from dose escalation?

PURPOSE: To evaluate the use of high-dose radiotherapy using carbon ions (C12) on non-adenoid cystic malignant salivary gland tumors (MSGT). PATIENTS AND METHODS: Between 2009 and 2013, patients with biopsy-proven non-ACC MSGT histologies of the head and neck received a combined regimen of IMRT plus C12 boost. Treatment toxicity (CTC v3), response (RECIST 1.1), control and survival rates were retrospectively analyzed. RESULTS: 40 patients with pathologically confirmed non-ACC MSGT (T4: 45 %; N+: 40 %; gross residual: 58 %; mucoepidermoid carcinoma (MEC): 45 %; adenocarcinoma: 20 %) were treated with a median of 74 GyE (80 Gy BED). Chemoradiation was given in 5 patients with MEC. Grade III acute toxicity was observed in up to 15 % (mucositis, dermatitis, dysphagia), no higher-grade late toxicity occurred to date. At a follow-up of 25.5 months, LC, and PFS at 2 and 3 years are 81.5 % (LC) and 66.8 % (PFS), OS at 2 and 3 years is 83.6 % and 72.8 %. Most frequent site of disease progression was distant metastasis. Histologic subtype correlated with LC and PFS. Resection status (gross vs microscopic disease) had no significant effect on LC, PFS, or OS. CONCLUSION: The treatment is well tolerated, no higher grade late effects were observed. Considering the negative pre-selection, LC, PFS and OS are promising. While histology and site of origin significantly influenced control and survival rates, resection status did not, potentially due to the effect of dose escalation.