Dosimetric evaluation of dysphagia in early stage larynx cancer treated with definitive radiotherapy
Purpose/Objective
Current studies have identified the relationship between organs at risk (OAR) doses and swallowing functions in patients with head and neck cancer treated with radiotherapy (RT). Our aim is to evaluate the relationship between OAR doses and acute dysphagia in early stage larynx cancer patients received definitive RT and to examine the effect of the RT technique on OAR doses.
Material/Methods
Early stage patients (Tcis-2N0M0) diagnosed between July 2014 and September 2022 were evaluated retrospectively. OAR (tongue base-TB, upper pharyngeal wall-UPW, middle pharyngeal wall-MPW, lower pharyngeal wall-LPW, whole pharyngeal wall-WPW, proximal esophagus-PE) were delineated subsequently and the dose-volume parameters were generated on previous treatment plans. Acute toxicities observed in the first 6 months were determined according to CTCAE v5. The relationship between OAR doses and grade(G) 2-3 dysphagia was investigated. For significant parameters (p<0.05), the cut-off values were determined by ROC analysis.
Results
Of the 43 patients, the median age was 69 years (range: 49-84) and 41 (95%) patients were male. The characteristic features of the patients were summarized in Table-1. The median follow-up was 30 (range: 1-101) months. The median local relapse-free survival was 30 (1-101) months and the 3-year local control rate was 94.3%. G1 dysphagia was observed in 21 (49%) of the patients and G2-3 dysphagia was observed in 19 (44%) patients. The dose volume parameters of OAR were summarized in Table-2. In terms of the relationship between Dmean(Gy), Dmax(Gy), V50(cc), V55(cc), V60(cc), V65(cc) values for the OARs of the patients and dysphagia; For WPW, V50(p=.03), V55(p=.03), V60(p=.02); For MPW, V50(p=.04), V55(p=.03), V60 (p=.05), V65(p=.03); For TB, V65(p=.03) were significantly associated with G2-3 dysphagia. In terms of G2-3 toxicity, for WPW; MPW and TB respectively: WPW V50> 13.3cc, V55> 12.9cc, V60 >12.5cc; MPW V50> 3cc, V55> 3cc, V60> 2.7cc, V65>0.6cc and TB V65>0.05cc were determined as cut off values. Intensity-modulated radiotherapy (IMRT) technique and volumetric arc therapy (VMAT) technique were used in 25 (58%) and 17 (40%) patients, respectively. When the planning technique and the average dose-volume parameters in OARs were compared, WPW-Dmean, V50,V55, V60, V65; UPW- Dmean, V55, V60; LPW-Dmean, V65 and PE-Dmax had significantly decreased in VMAT plans. However, there was no clinically significant difference between the two techniques in terms of dysphagia (p = .41). Local recurrence was observed in 4 (9%) patients during follow-up. Both regional and distant metastases were detected in only 1 patient. At the last follow-up 7 patients (16%) died due to non-cancerous reasons, 36 patients (84%) were disease free with complete response.
Table-1: Characteristic features of patients
| Features | Number (%) |
| Performance ECOG1 ECOG2 |
33(77%) 10(23%) |
| Cigarette Current Ex-smoker Never |
11(26%) 25(58%) 6(14%) |
| Pathology SCC Other |
42(98%) 1(2%) |
| T Stage Carcinoma in situ T1 T2 |
13(30%) 27(63%) 3(7%) |
| Radiotherapy Technique 3D CRT IMRT VMAT |
1(2%) 25(58%) 17(40%) |
| RT Dose 63Gy/28fx 64.4Gy/28fx 65.3Gy/29fx Other |
29(67%) 6(14%) 5(12%) 3(7%) |
| Dysphagia Grade 1 Grade2 Grade3 |
21(49%) 16(37%) 3(7%) |
Table-2:The dose volume parameters of OAR
| Dmean(Gy) |
Dmax(Gy) |
Volume(cc) |
V50(cc) |
V55(cc) |
V60(cc) |
V65(cc) |
|
|
WPW UPW MPW LPW PE TB |
29±6 6±7 57±15 65±2 13±7 7±6 |
67±1 39±24 65±10 67±1 62±10 61±15 |
36±7 21±5 4±1 10±2 11±2 38±7 |
15±4 1±1 4±1 10±2 1±1 2±3 |
14±4 1±1 3±2 10±2 1±1 2±3 |
14±4 1±1 3±2, 10±2 1±1 1±2 |
7±6 0±1 1±2 5±4 0±1 1±1 |
Conclusion
In this study, a significant relationship was observed between acute G2-3 dysphagia and WPW, MPW, TB dose volume values in early stage laryngeal cancer receiving definitive RT. Although there was a decrease in OAR values with the VMAT plans, no clinical significance was determined between RT techniques.
