Volume 84 � Number 3S � Supplement 2012 Poster Viewing Abstracts S495

adjustments, the trends could be largely compensated with eNAL (SI

margin 3.5 mm). Correlation between movements of the primary and nodal

CTVs in SI direction was poor (r2 Z 0.15). For this reason, even with

perfect on-line set-up corrections of the primary CTV (no residual errors),

the required SI margin for the nodal CTV would be as large as 7 mm. In

Left-Right (LR) and Anterior-Posterior (AP) directions, movements of the

primary and nodal CTVs were largely correlated (r2 Z 071/0.64). Even

with the two off-line protocols, required PTV margins in LR and AP

directions were limited to 2-3 mm for both CTVs. SI motion correlation

between the cervical vertebrae and the primary CTV was poor ((r2 Z0.19). When using the vertebrae as reference structure in image guidance,

the required SI margin around the primary CTV would be 7 mm, even with

daily on-line repositioning.

Conclusions: Without set-up corrections, laryngeal cancer patients showed

large SI interfraction time trends in set-up of the primary tumor that could

partially or almost fully be compensated with eNAL and daily on-line,

respectively. Due to poor SI motion correlation of the primary tumor and the

nodes, even perfect daily repositioning of the primary CTV required a 7 mm

PTV margin around the nodes. Small nodal PTV margins would require an

adaptive approach to correct for the non-rigid motion. Even with daily on-

line corrections, the required SI PTVmargin around the primary CTVwould

be as large as 7mm, when using the vertebrae as reference structure in image

guidance. Generally applied 5 mm PTV margins in head and neck cancer

were often inadequate for the studied laryngeal cancer patients.

Author Disclosure: B. Heijmen: None. A. Gangsaas: None. E. Astreinidou:

None. S. Quint: None. P. Levendag: None.

2736WITHDRAWN

2737Radiation Treatment of T1-T2N0 Squamous Cell Carcinoma of theGlottic Larynx in the Modern EraJ. Johansen,1 S. Madsen,1 A. Wentzer,1 and C. Godballe2; 1Odense

University Hospital, Department of Oncology, Denmark, 2Odense

University Hospital, Department of ENT Head and Neck Surgery,

Denmark

Purpose/Objective(s): The 2006 ASCO Clinical Practice Guideline for

the treatment of laryngeal cancer has recommended single-modality

treatment for limited-stage (T1-T2) invasive cancer of the glottic larynx

with no preference for surgery or radiation therapy. The recommendations

regarding radiation treatment were based predominantly on data from the

90es. This study describes tumor control and larynx preservation after

radiation treatment for T1-T2N0 glottic cancer in 2000-2010 from a single

health care region in Denmark.

Materials/Methods: From the regional DAHANCA-database, patients

treated with radiation during 2000-2010 for invasive squamous cell carci-

noma of the vocal cords were retrieved. Cases of dysplasia or in situ carci-

noma were excluded. The hospital serves the Region of Southern Denmark

with 1.2 million inhabitants. Patient and treatment characteristics of 196 T1-

T2N0 glottic cases receiving primary radiation treatment without surgery

were reviewed by two academic staffmembers, and update of vital statuswas

performed through electronic medical records and from national health care

registries. Radiation dose prescriptions were 62-68 Gy in 33-34 fx, 5-6 fx/w.

Results: Only 13 local recurrences (6.6%) were observed after a median

follow-up time of 3.1 years. The cause-specific survival rate at 5 years was

95.7%. Actuarial local control rates at 5 years after radiation therapy for T1-

tumors was 95.2% (95% CI: 91.1-99.3%), 97.4% for T1a, and 87.9% (95%

CI: 80.1-96.0%) for T2 tumors. Only 15 patients were recorded with T1b

tumors, having a comparable control rate to T2. Laryngeal preservation was

94.4% (95% CI: 93.0-99.9%). On multivariate analysis, only T-stage was

associated with local tumor control, however, as described, events were few.

Conclusions: Modern radiation treatment using fractionation schedules

around 66Gy during 5½-6½weeks produces excellent tumor control rates for

bothT1andT2 tumors. T1b tumors didnot differ fromT2 tumors in this study.

Author Disclosure: J. Johansen: None. S. Madsen: None. A. Wentzer:

None. C. Godballe: None.

2738Is IMRT Associated With Inferior Outcomes for T1-2N0 SquamousCell Carcinoma of the Larynx?N. Riaz, S. Jaffery, M. Hu, S. Wolden, S. Rao, and N. Lee; Memorial

Sloan-Kettering Cancer Center, New York, NY

Purpose/Objective(s): Some investigators have reported an increased rate

of local failure with IMRT compared to conventional radiation therapy in

the treatment of early laryngeal carcinoma. We sought to examine our

experience with these two modalities to determine if there was a difference

in local control.

Materials/Methods: Three hundred thirty consecutive patients with early

stage laryngeal carcinoma were treated at our center between January 1989

and February 2011. There were 257 T1 and 73 T2 tumors. Among those

with T2 disease, 23 had supra-glottic extension, 35 had sub-glottic

extension and 15 had impaired vocal cord mobility. Patients were either

treated with conventional parallel opposed lateral technique (convRT) or

with IMRT. Patients treated with IMRT underwent a CT or PET/CT

simulation. The GTV was defined as disease visualized on physical

examination and any abnormality visualized on imaging. The CTV

included the entire larynx (the false and true vocal cords, the anterior and

posterior commissures, arytenoids, and AE folds) allowing for a margin

around the GTV. The PTV typically extended from the bottom of the

cricoid cartilage to the bottom of the hyoid. Local Control (LC) and overall

survival (OS) were determined by the Kaplan-Meier method. Differences

in LC between groups was evaluated with the log-rank test.

Results: Fifty-one patients were treated with IMRT and 279 patients were

treated with convRT. The median follow-up for the entire cohort was 60

months. Median follow up in IMRT patients was 20 months (range 1-52)

compared to 71 months for convRT (range: 1 - 251). The two groups were

well balanced for T stage. The median dose of radiation was 66Gy (range:

50.4Gy - 70.2Gy). In the IMRT group, 88% received hypo-fractionated

treatment with 2.25 Gy fractions (63 - 65.25Gy) compared 27% in convRT

(p < 0.001). The crude rate of failure was 5.8% in the IMRT group (3/51)

compared to 4.3% in the RT group (12/279). The 2 year actuarial rates of

LC was 97% with convRT compared to 91% with IMRT (pZ0.18). In

patients treated with hypo-fractionation, 2 year LC was 97% in convRT

compared to 90% in IMRT (pZ0.286). There no difference in LC in the

subset of T2 patients (pZ0.684) either. All three local failures in the IMRT

group occurred in the vocal cord. One patient with T1 disease failed

synchronously in the sub-glottis, likely marginal to the PTV. The 2 and 5

year overall survival for the entire cohort was 95% and 86% respectively.

Conclusions: Our preliminary experience did not show a statistically

inferior outcome of early glottic tumors treated with IMRT vs. convRT.

These encouraging results are likely attributable to our conservative

approach of including the entire larynx as the target. Longer follow-up is

warranted to confirm this result.

Author Disclosure: N. Riaz: None. S. Jaffery: None. M. Hu: None. S.

Wolden: None. S. Rao: None. N. Lee: None.

2739Excellent Laryngeal Preservation Can Be Achieved With IMRT forLocoregionally Advanced Laryngeal CancerM. Hu, E. Katsoulakis, N. Riaz, S. Jaffery, S. Rao, and N. Lee; Memorial

Sloan-Kettering Cancer Center, New York, NY

Purpose/Objective(s): Due to concerns that the laryngeal apparatus can

have significant motion during radiation therapy, some investigators have

been reluctant to use intensity-modulated radiation therapy (IMRT) in the

treatment of larynx cancer. Our purpose was to present the long-term

treatment outcomes and to see if there was a difference in outcomes for

a cohort of loco-regionally advanced laryngeal cancer treated with or

without IMRT.

Materials/Methods: Between 3/00 and 8/11, 206 patients with squamous

cell carcinoma (SCC) of the loco-regionally advanced laryngeal cancer