Main Session
Sep 29
QP 32 - Patient Reported Outcomes/QoL/Survivorship Quick Pitch

1191 - Swallowing Outcomes with Intensive Midline-Sparing IMRT in Nasopharyngeal Carcinoma

05:40pm - 05:45pm ET
Room 256

Presenter(s)

Janjira Petsuksiri, MD Headshot
Janjira Petsuksiri, MD - Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkoknoi, KRUNG THEP MAHA

J. Petsuksiri1, P. Amnuaysin1, T. Treechairusame1, J. Setakornnukul1, K. Thephamongkhol1, W. Pongsapich2, and P. Keskool2; 1Division of Radiation Oncology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand, 2Department of Otorhinolaryngology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand

Purpose/Objective(s):

Dysphagia is a common and clinically meaningful toxicity following radiotherapy (RT) for head and neck cancers. Dysphagia-optimized IMRT has shown improved swallowing outcomes in oropharyngeal cancer; however, no randomized data have evaluated dose-reduction strategies to swallowing structures in nasopharyngeal carcinoma (NPC). We compared dosimetric and swallowing-related outcomes between intensive midline-sparing IMRT (IMS-IMRT) and standard IMRT (S-IMRT) in NPC patients.

Materials/Methods:

IMS-IMRT was introduced at our institution in 2019. In this retrospective cohort study, patients were treated with either IMS-IMRT or S-IMRT. Allocation to IMS-IMRT was physician-directed to prioritize sparing of midline swallowing structures and was not based on baseline patient or tumor characteristics. Dosimetric analysis focused on midline swallowing structures. The composite primary endpoint was =10% body weight loss and/or feeding tube insertion during RT and within 3 months after RT. Secondary endpoints included individual Thai MD Anderson Dysphagia Inventory (TH-MDADI) scores and clinical outcomes.

Results:

A total of 115 patients were included (IMS-IMRT n=31; S-IMRT n=84) with a median follow-up of 55 months (IQR 49–58). Dosimetric parameters were significant improved with IMS-IMRT (Table 1). The mean dose to the pharyngeal constrictor muscles was consistently lower in the IMS-IMRT group across all T and N stages. IMS-IMRT significantly reduced =10% weight loss during RT (16% vs 40%, p=0.015) and the composite endpoint during RT (23% vs 46%, p=0.031). Differences were not observed beyond RT completion. Overall feeding tube use was numerically lower with IMS-IMRT (10% vs 19%, p=0.27). TH-MDADI composite scores were comparable (94.8±10.2 vs 91.6±11.8, p=0.34), with trends toward improved global domain (91.25 + 20.62 vs 78.05 + 28.92, p=0.10) and physical domain (92.66 +14.82 vs 86.4 +17.70, p=0.22) in the IMS-IMRT group. Oncologic outcomes were similar between 2 groups: 3-year locoregional recurrence-free survival (94.9% vs 84.9%, p=0.58), 3-year disease-free survival (82.9% vs 78.9%, p=0.32), and estimated 5-year overall survival (86.4% vs 90.5%, p=0.99).

Conclusion:

IMS-IMRT reduced acute weight loss and composite swallowing-related events during RT. Midline dose reduction demonstrating a trend toward decreased dysphagia without compromising oncologic outcomes.

Table 1: Dosimetric outcomes

Structures

 IMS-VMAT (n=31)

 S-VMAT (n=84)

 p-value

Dose (Gy) (mean +/- SD)

 Dose (Gy) (mean +/- SD)

Base of tongue

 38.02 ± 5.30

 45.14 ± 6.93

 <0.001
Superior PCM

 59.96 ± 6.33

 64.96 ± 4.74

 <0.001
Middle PCM

 39.75 ± 5.14

 47.99 ± 5.83

 <0.001
Inferior PCM

 32.30 ± 6.59

 40.93 ± 5.98

 <0.001
Cricopharyngeus

 31.41 ± 6.09

 40.44 ± 6.13

 <0.001
Esophageal inlet

 30.63 ± 6.01

 41.01 ± 7.69

 <0.001
Esophagus

 31.89 ± 6.22

 38.79 ± 7.21

 <0.001
Supraglottic larynx

 29.50 ± 5.32

 40.24 ± 7.48

 <0.001
Glottic larynx

 27.34 ± 7.30

 35.14 ± 6.84

 <0.001
Oral cavity

 33.06 ± 3.63

 37.92 ± 5.64

 <0.001