Volume 84 � Number 3S � Supplement 2012 Poster Viewing Abstracts S609

a decreased DMFS (pZ0.034). Concurrent chemotherapy (pZ0.006) and

non-squamous histology (pZ0.020) were associated with improved OS.

Concurrent chemotherapy was also associated with improved LRPFS

(pZ0.029).

Conclusions: In one of the largest reported series for reRT in the setting of

NSCLC, we found that when utilizing conformal techniques and with

appropriate patient selection, this method was well tolerated with prom-

ising survival outcomes. Patients with non-squamous histology who

received concurrent chemotherapy with reRT may be representative of

a group with particularly good outcomes.

Author Disclosure: S.A. McAvoy: None. R. Komaki: None. P. Allen:

None. J. Rineer: None. Z. Liao: None. J. Chang: None. J. Welsh: None. M.

Palmer: None. J. Cox: None. D. Gomez: None.

3038Dosimetric Evaluation of Flattening Filter-free (FFF) Photon Beamsfor Lung SBRTQ. Chen, J. Cai, Q. Wu, and F. Yin; Duke University Medical Center,

Durham, NC

Purpose/Objective(s): Some modern linear accelerator offers new energy

modes of flattening-filter free (FFF) with high dose rate at 1400 MU/Min

for 6MV-FFF and 2400 MU/Min for 10MV-FFF photon energies. This

study aimed to evaluate the dosimetric quality with the FFF photon energy

modes for lung stereotactic-body radiation therapy (SBRT), as compared

to the standard photon energies.

Materials/Methods: Ten (10) lung cancer patients who underwent SBRT

treatments at our institution were included in this study. All original SBRT

plans were made using 3D-CRT technique with 6MV photons. New plans

using the 6MV-FFF and 10MV-FFF were generated based on the original

plans at the same beam arrangement, collimation and MLC shape to

preserve the original plan details as much as possible. All plans were

generated in Eclipse v10.0 planning system All doses were calculated with

AAA algorithms. Dose-volume histogram, total MUs, estimated beam-on

time, max and mean doses of the PTV, V20Gy of the lungs, conformity

indices for 100% (CIPrx) and 50% (CI50) isodoses of the prescribe dose

were measured and compared between the FFF and the original 6MV

plans.

Results: The median PTV volume is 16.3 cm3..The differences in CIPrx,

CI50, Lung V20Gy, Dmax, and Dmean were 0.01�0.10, 0.17�0.76,

0.17%�0.24%, 1.3%�2.6%, and 0.1%�1.0%, respectively, between

10MV-FFF plans and standard 6MV plans (p>0.05 in all), and were

-0.02�0.06, -0.12�0.5, 0.05%�0.00%, -1.3%�1.6%, -0.5%�0.5%

between 6MV-FFF plans and standard 6MV plans (p>0.05 except for

Dmax (pZ0.03) and Dmean (pZ0.01)). FFF plans didn’t show any

significant improvement over standard 6MV plans in terms of dosimetric

characteristics. In general, dose-volume histogram was comparable

between the FFF plans and the standard 6MV plans. The 6MV-FFF energy

mode is slightly better than 10MV-FFF energy mode in CIPrx, CI50, Lung

V20Gy. Seven (7) out of 10 6MV-FFF mode plans achieved about 2%

better on CI prx, CI50% than those using the standard 6MV mode. Those

2% achievements are minimal in term of the absolute numeric differences,

which are less than 0.2. The small dosimetric difference is expected due to

relatively flat beam profiles at the central axis for these FFF modes, which

is used by the small fields by SBRT. The FFF mode reduced total beam-on

time in our ten cases is more than 2 minutes, which is 56%�1 reduction

for 6MV-FFF and 68% �11 for 10MV-FFF.

Conclusions: The new FFF energy modes achieved comparable dosimetric

quality as the standard flat beam. The 6MV-FFF mode differs significantly

from the standard 6MV mode in Dmax Dmean and CI, but the absolute

differences are small and clinically insignificant. The FFF mode plans have

similar MUs as the standard mode, but substantially reduced beam-on time

due to the high dose-rate, which is potentially beneficial for breath-hold

SBRT treatment.

Author Disclosure: Q. Chen: None. J. Cai: None. Q. Wu: None. F. Yin:

None.

3039Long-term Follow-up and Patterns of Failure for Patients WithMedically Inoperable Stage I Non-small Cell Lung Cancer (NSCLC)Treated With Stereotactic Body Radiation Therapy (SBRT)J.J. Urbanic, M. Soike, C.J. Hampton, J. Lucas, W. Hinson, W. Kearns,

and A.W. Blackstock;Wake Forest School of Medicine, Winston Salem, NC

Purpose/Objective(s): SBRT program at this institution began in 2002.

We reviewed all patients with medically inoperable Stage I NSCLC treated

with SBRT prior to 2009 as these patients would have potential minimum

3 years of follow-up.

Materials/Methods: All patients were treated using the Bodyframe for

immobilization and abdominal compression on a conventional LINAC.

Target localization based on stereotactic coordinates with orthogonal MV

portal imaging for confirmation. 4D CT used to define ITV beginning

January 2007 (52 patients). PTV expansion of 5 mm used in ITV defined

patients PTVotherwise 5 mm axial, 10mm cranial caudal. 19 patients prior

to 2006 treated using homogeneous tissue density. Patients scored for local

(at the site treated), regional (nodal disease in hilum or mediastinum), or

distant sites of failure. Toxicity graded per NCI CTCAE v4.0. Descriptive

statistics used to report toxicity. Kaplan Meier estimate of local control,

recurrence, survival.

Results: Eighty-five patients, stage I NSCLC identified who were treated

with SBRT 2003-2008. Median follow-up 31 months (0-83 months). For

living patients, median follow-up 39 months (1-83 months); 4 living

patients with fu <21 months lost to follow-up. Average patient age 71.3

years (46-87). Average smoking pack-years 56.2 (4-150 years). Pre-treat-

ment pulmonary function testing 45 patients: FEV1 median 54%, 34

patients: DLCO 55.3% predicted. Eighteen patients’ prior lung surgery, 7

patients treated for bilateral stage I lung. 76 of 85 patients pathologically

diagnosed. Average tumor size 2.3cm (0.7-3.9). 72 tumors were T1, 13

tumors were T2. The most common dose (45 pts) was 5400 cGy in 3

fractions (2250-6000 cGy). 48 deaths occurred. Median survival 38 months

(95% CI 27-49 months); 5 year overall survival 28.7% (95% CI 15-42%).

Local failure in 11 patients. Local control at 3 years 84.5% (95% CI 74-

94%). Regional recurrence 9 patients (7 isolated without local failure) 3

year freedom from regional nodal failure 88.2% (95% CI 79-97%); 6 of 9

regional failures occurred after 2 years. Distant failure predominated in 24

of 85 patients at a median of 20.8 months. 3 year freedom from distant

failure 75.6% (95% CI 65-86%). DF isolated in 15 patients but DF in 8 of

11 patients with local failure. 9 of 11 patients with LF died with disease.

LF treated with thermal ablation (2), chemo (4) and no tx (5). Grade 3 or

higher pulmonary toxicity occurred in 4 patients with one probable grade 5

toxicity in a patient with severe underlying COPD.

Conclusions: Patients treated using SBRT had expected median survival of

3 years with 29% chance at long term survival. Most patients with local

failure died of disease suggesting importance of local control. Salvage tx

options were limited.

Author Disclosure: J.J. Urbanic: None. M. Soike: None. C.J. Hampton:

None. J. Lucas: None. W. Hinson: None. W. Kearns: None. A.W. Black-

stock: None.

3040Role of Radiation Therapy in Small Cell Lung Cancer (SCLC):Analysis of SEER-17 DataF.P. Kong,1 W.O. Quarshie,2 N. Bi,1 N. Kapadia,1 and F. Vigneau2;1University of Michigan, Ann Arbor, MI, 2Wayne State University, Detroit,

MI

Purpose/Objective(s): The overall survival benefit of radiation therapy is

not well defined in small cell lung cancer (SCLC). Current data on SCLC

is largely stratified by limited vs extensive stages. This study aimed to

examine 1) AJCC stage distribution, 2) the use of local treatment modality

such as radiation therapy (RT), and 3) survival benefit of RT in patients

with SCLC.

Materials/Methods: The study population includes primary SCLC from

the SEER-17 database 1999-2008. The data were stratified by AJCC stage