ESTRO 2024 - Abstract Book

S1354

Clinical - Head & neck

ESTRO 2024

Female

11 (64%)

Site

Nasal cavity/Paranasal sinus

16 (94%)

Oral cavity/ hard palate

1 (6%)

Stage

Stage III

3 (18%)

Stage IV

14 (82%)

Treatment

CIRT alone

2 (12%)

CIRT + Surgery

6 (36%)

CIRT + Immunotherapy

9 (52%)

CIRT dose

Median [Gy (RBE)]

68.8

Range [Gy (RBE)]

60.2 - 68.8

Results: MMM patients (n =17) treated with CIRT from March 2020 -April 2023 were analyzed (Table 1). Tumor stages: stage 3: 3 (18%), stage 4: 14 (82%). The median follow up was 14 months (range, 4-43). Median overall CIRT treatment time was 27 days (range, 22-49). Two-year local-regional recurrence free survival, distant metastasis free survival and overall survival was 91% (CI, 0.51-0.99), 55% (CI, 0.27-0.76) and 70% (CI, 0.42-0.86) respectively (Figure 1). Tumor regression kinetics show median tumor regression of tumor at 3, 6 and 12 months post-CIRT up to 40%, 63% and 72% respectively (Figure 2). Eight patients developed distant metastasis of which two were salvaged with surgical resection of oligometastases; one patient developed regional nodal recurrence 1-year post-CIRT which was salvaged by surgery and immunotherapy and two received immunotherapy alone. Another patient developed marginal recurrence and was salvaged by CIRT and immunotherapy. None of the patients developed in field failures. Five patients died of progressive metastatic disease. The toxicity associated with immunotherapy (CTCAE v5) were: endocrinopathy gr 2: 1 (10%), gastro- enteritis grade ≥ 3: 1 (10 %). Acute toxicities associated with CIRT (CTCAE v5) were: radiation dermatitis gr 2: 5 (29%), mucositis gr 2: 7 (49%) and conjunctivitis gr 2: 3 (18%). The late toxicities associated with CIRT (CTCAE v5) were: dysgeusia gr 2: 1 (6%), fatigue gr 2: 1 (6%), xerostomia gr 2: 1 (6%), epiphora grade 2: 2 (18%) (Table 1). None of the patients developed severe late toxicity. LEM-I and mMKM, D RBE statistics and dose averaged LET (LETd) were analysed for for targets and OARs (data not shown here).