Head and Neck Cancer

PD 10 - H&N 2 - Head and Neck Poster Discussion

1084 - Retropharyngeal Lymph Node Involvement in Human Papillomavirus (HPV)-Associated Oropharyngeal Cancer (OPC)

Tuesday, October 23
1:18 PM - 1:24 PM
Location: Room 217 A/B

Retropharyngeal Lymph Node Involvement in Human Papillomavirus (HPV)-Associated Oropharyngeal Cancer (OPC)
T. Lin1,2, H. Elhalawani3, B. Elgohari1, M. Debnam1, A. Jethanandani1,4, S. P. Ng1, A. S. Mohamed1, S. J. Frank1,5, E. M. Sturgis1, J. Phan1,6, J. Reddy1, C. D. Fuller5,7, W. H. Morrison1, H. D. Skinner1, D. I. Rosenthal1, A. S. Garden1, and G. B. Gunn1; 1The University of Texas MD Anderson Cancer Center, Houston, TX, 2Baylor College of Medicine, Houston, TX, 3Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, 4The University of Tennessee Health Science Center College of Medicine, Memphis, TN, 5Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 6Dept. of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 7University of Texas Graduate School of Biomedical Sciences, Houston, TX

Purpose/Objective(s): We aimed to characterize the incidence, nodal pattern/volume, and impact on oncologic outcomes associated with radiographic RPLN involvement in HPV-associated OPC.

Materials/Methods: We retrospectively analyzed a cohort of HPV-associated OPC patients treated at our institution from 2004-2013, after IRB approval. Demographic, clinical, and outcomes data were collected from the electronic medical record. Tumors were considered HPV-associated if positive for either p16 or HPV. Radiographically evident RPLNs were identified and manually segmented on pre-treatment contrast-enhanced CT by two radiation oncologists and evaluated by a third radiation oncologist. Univariate analysis was performed using Cox proportional hazards model with respect to RPLN status. RPLN volume by primary site was compared using one-way analysis of variance.

Results: We reviewed pre-treatment images of 796 HPV-associated OPC patients, in whom 75 (9.4%) had radiographically involved RPLN(s). Of those with positive RPLN, tonsil was the most common primary site (64% or 48/75). However, highest site-specific incidence of positive RPLN were soft palate (29%) and pharyngeal wall (33%) (Table 1). Bilateral RPLN involvement was observed in 4 patients (all but one had >T2 disease). All positive RPLNs were lateral; no positive median RPLN was identified. An isolated ipsilateral positive RPLN was identified in 6 and bilateral RPLNs in 1 patient(s), who were otherwise cN0. A contralateral positive RPLN was identified in 6 without presence of a positive ipsilateral RPLN (4 BOT and 2 tonsil primaries; 4 had either T4 or extensive nodal disease). Overall, median involved RPLN volume was 1.2 cc (range: 0.1 - 10.3 cc). Median positive RPLN volume (Table 1) was highest in tonsil (1.65 cc) and lowest in BOT (0.8 cc) primaries, but this was not statistically significant. Median follow-up time was 60 months. 5-year rates of local control, regional control, distant-metastases-free survival, and overall survival by RPLN status are shown in Table 1. On univariate analysis, RPLN involvement was associated with worse overall survival (p=.0215) and distant metastases-free survival (p=.0273).

Conclusion: These results, now in a HPV-associated OPC cohort, confirm our previous findings of a negative influence of RPLN involvement on patient survival and development of distant metastases, and despite their small volume, RPLN involvement should be considered a marker of regionally advanced disease. Table 1
RPLN- RPLN+ Overall Cohort Median RPLN Volume (cc) Univariate Analysis
Primary Tumor Site, N (%) BOT 347 (94%) 21 (6%) 368 0.85 -
Tonsil 316 (87%) 48 (13%) 364 1.65 -
Soft Palate 5 (71%) 2 (29%) 7 1.3 -
Pharyngeal Wall 2 (67%) 1 (33%) 3 1.8 -
NOS 51 (94%) 3 (6%) 53 1.0 -
5-Yr Rates Local Control 94% 96% - - P=.4264
Regional Control 93% 96% - - P=.4227
Distant Metastases-Free Survival 93% 84% - - P=.0273
Overall Survival 87% 74% - - P=.0215

Author Disclosure: T. Lin: None. H. Elhalawani: None. B. Elgohari: None. M. Debnam: None. A. Jethanandani: None. S. Ng: Employee; The University of Texas MD Anderson Cancer Center. A.S. Mohamed: None. S.J. Frank: Research Grant; C4 Imaging, ELEKTA, U19. Founder and Director; C4 Imaging. Honoraria; ELEKTA, Varian Medican Systems, Inc. Advisory Board; Varian Medican Systems, Inc. Stock; C4 Imaging. Royalty; C4 Imaging. Patent/License Fees/Copyright; C4 Imaging. Chairman; American Brachytherapy Society. Director; C4 Imaging. Director-at-large; North America Skull Base Society. E.M. Sturgis: None. J. Phan: None. J. Reddy: None. C.D. Fuller: Research Grant; National Institutes of Health, National Science Foundation, Elekta AB. Grant funding; Elekta AB. Honoraria; Nederlandse Organisatie voor Wetenschappelijk Onde. Consultant; Elekta AB, Nederlandse Organisatie voor Wetenschappelijk Onde. Travel Expenses; Elekta AB, Nederlandse Organisatie voor Wetenschappelijk Onde. Reviewer; Radiological Society of North America. Associate Editor; Radiographics. Data Management Task Force Committee Member; MR-LinAc Consortium. Member; National Cancer Institute. Task Group Member; American Association of Physicists in Medicine. W.H. Morrison: Advisory Board; Regeneron. Stock; Merck, Baxter, Johnson and Johnson. Member; NCCN Nonmelanoma Skin and Merkel Cell Committees. H.D. Skinner: None. D.I. Rosenthal: None. A.S. Garden: None. G.B. Gunn: Associate Medical Director; MD Anderson Cancer Center - Proton Therapy.

Timothy Lin, BA

Disclosure:
No relationships to disclose.

Presentation(s):

Send Email for Timothy Lin


Assets

1084 - Retropharyngeal Lymph Node Involvement in Human Papillomavirus (HPV)-Associated Oropharyngeal Cancer (OPC)



Attendees who have favorited this

Please enter your access key

The asset you are trying to access is locked. Please enter your access key to unlock.

Send Email for Retropharyngeal Lymph Node Involvement in Human Papillomavirus (HPV)-Associated Oropharyngeal Cancer (OPC)