S88 I. J. Radiation Oncology d Biology d Physics Volume 69, Number 3, Supplement, 2007

control rate of 95%. Regional and distant failures were observed in 5 patients (7%) and 12 patients (18%), respectively. The ac-tuarial regional-failure-free survival at 1 and 2 years was 94% and 83%. Corresponding figures for distant failure-free survival were80% and 76%. The disease-free survival was similar for patients with and without pathological confirmation of malignancy (Fig-ure). Minor early toxicity consisting of fatigue (44%), nausea (12%) and chest pain (10%) was observed. Late toxicity was limitedto grade $3 radiation pneumonitis seen in 2 patients (3%), rib fractures (3%) and chronic thoracic pain syndromes (3%).

Conclusions: Even in ‘high risk’ patients with stage I NSCLC, SRT based upon 4DCT planning with a BED of more than 100Gy10, results in local control rates exceeding 90%, with acceptable toxicity. Despite the routine use of pre-treatment FDG-PETscans, the development of distant metastases remains the most common pattern of relapse.

Author Disclosure: F.J. Lagerwaard, None; C.J.A. Haasbeek, None; E.F. Smit, None; B.J. Slotman, None; S. Senan, None.

155 Image-Guided, Intensity-Modulated Hypofractionated Radiotherapy for Inoperable Non-Small Cell Lung

Cancer: Preliminary Results of a Phase I Dose Escalation Study

J. B. Adkison, G. M. Cannon, D. Khuntia, H. Jaradat, W. Tome, W. Walker, B. Huang, M. Mehta

UW Radiation Oncology Clinic, Madison, WI

Purpose/Objective(s): A prospective, Bayesian, volume-dose binned (using projected pneumonitis rates) phase I study for locallyadvanced and medically inoperable patients was devised to escalate the biologically effective dose while limiting the dose to criticalnormal structures including the esophagus, spinal cord, and residual lung. Here we report initial toxicity results.

Materials/Methods: Forty-one patients judged not to be surgical candidates due to medical comorbidities or advanced stage(Stage I-IV NSCLC) were enrolled. Concurrent chemotherapy was not allowed. IMRT/IGRT was delivered via helical tomother-apy and limited to the primary site and clinically proven or PET/CT suspicious nodal regions (no elective nodal irradiation). Pa-tients were placed in 1 of 5 bins, based on predicted pneumonitis risk, all treated for 25 fractions, with dose per fraction rangingfrom 2.28 to 3.22 Gy, yielding normalized tissue dose (NTD) equivalents in 2 Gy fractions of 58.34–88.68 Gy10, with starting dosesdetermined by the relative normalized tissue mean dose (rNTDmean) predicted for 20% Grade 2 pneumonitis. Dose escalation upperlimit constraints included lung NTD mean\32 Gray, spinal cord maximum NTD of 50 Gy, esophageal maximum NTD of 64 Gy3,and esophageal effective volume (Veff) of 30%.

Results: No grade 3 RTOG acute pneumonitis (NCI-CTC v.3) or esophageal toxicities (CTCAE v.3.0 and RTOG) were observed.Pneumonitis rates were 19.5% Grade 0, 68.3% grade 1, and 12.2% grade 2. No grade 2 pneumonitis was observed in any patientwith lung NTD mean less than 11.4 Gy4. Only 7 patients (17.07%) required narcotic analgesia (RTOG gr. 2 toxicity) for esoph-agitis. At a median follow-up of 6.8 months, the complete response rate is 21.4%, partial response rate of 41.5%, in-field thoracicprogression is 7.3%, out-of-field thoracic progression is 9.8%, and extrathoracic distant failure is 24.4%.

Conclusions: Dose escalation through hypofractionation can safely be achieved in non-small cell lung cancer with lower than ex-pected rates of pneumonitis and esophagitis using image-guided, intensity-modulated radiation therapy. Dose-escalation on thistrial continues.

This work is funded by the NIH/NCI 1PO1CA88960 Improving Cancer Outcome with Adaptive Helical Tomotherapy ProgramProject Grant.

Author Disclosure: J.B. Adkison, None; G.M. Cannon, None; D. Khuntia, None; H. Jaradat, None; W. Tome, None; W. Walker,None; B. Huang, None; M. Mehta, None.

156 4-D CT Based and Daily In-room CT-guided Stereotactic Body Radiotherapy (SBRT) for Lung Cancer

J. Y. Chang, P. Balter, L. Dong, Z. Liao, K. M. Bucci, M. Jeter, M. F. McAleer, Q. Yang, J. D. Cox, R. Komaki

M.D. Anderson Cancer Center, Houston, TX

Purpose/Objective(s): To evaluate the therapeutic efficacy of image-guided SBRT and treatment-related toxicities in patients withperipherally or centrally located, medically inoperable stage I or isolated recurrent NSCLC.

Proceedings of the 49th Annual ASTRO Meeting S89

Materials/Methods: 113 patients with NSCLC who underwent 4-D CT based planning and daily CT-on-rail guided SBRT werestudied. The internal gross target volume (IGTV) was delineated and verified for each respiratory phase of the 4D CT data set. Theclinical target volume consisted of the IGTV plus an 8-mm margin. A 3-mm setup uncertainty margin was added to the planningtarget volume (PTV). Daily alignments, range of shifts from the external setup marks were analyzed. The GTV position in daily CTscan was aligned and compared to the aligned bony reference structure.

Among 73 patients with clinical outcome data, 46 had stage I disease and 27 had isolated recurrent disease. 21 patients had cen-trally located lesions, defined as within 2 cm of the bronchial tree, major vessels, esophagus, heart, or other mediastinal structures,but no direct invasion. The prescribed dose was 50 Gy (40 Gy for in-field recurrent disease) to the PTV delivered in 4 consecutivedays. Dosing to the major mediastinal critical organs was restricted to 40 Gy delivered to less than 10 cc except for the esophagus,for which dosing was restricted to no more than 1 cc at 40 Gy.

Results: Daily shifts (mean 3D vector: 0.9 ± 0.6 cm; range 0–3.3 cm) from the external marks to the final treatment position wererequired. Statistically significant inter-fractional GTV shifts relative to the bone happened in 30% of cases and systematic trend ofmore than 5 mm occurred in 10% of cases. Daily CT on-rail provides the advantage of 3-D bony alignment and soft tissue visibilitythat guided the decision of the final treatment position.

With 3 to 28 months follow-up, the overall progression-free survival rate at the treated site was 95.9%. For stage I disease, thecomplete response (CR), partial response (PR), and stable disease (SD) rates were 43.5%, 33.3%, and 21.0%, respectively. Nosignificant differences in response rate were seen between stage Ia (n = 39) and Ib (n = 7) disease. Two (4.3%) and three patients(6.5%) with stage I disease developed mediastinal lymph node or distant metastasis respectively. For patients with isolated recur-rent disease, the CR, PR, and SD rates were 51.9%, 25.9%, and 15.8%, respectively. Three (11.1%) and five (18.5%) of these pa-tients experienced mediastinal lymph node metastasis or distant metastasis respectively. In stage I disease, 6.5% (three patients) hadgrade 2 but no grade 3 or above radiation pneumonitis. In three patients with recurrent disease, dyspnea worsened after SBRT, andone patient needed nasal oxygenation/hospitalization. No esophagitis was noted in all patients. Grade 2 and 3 dermatitis developedin 22.8%, 4.1% respectively of patients at the treated site, which appeared to be related to the dose (.35 Gy) and volume of skintreated. Three patients developed chronic skin scar, and five had chronic mild neurogenic chest pain due to intercostal nerve injury.No increased toxicity was noted in centrally located lesions than in peripherally located lesions.

Conclusions: Image-guided SBRT using 50 Gy delivered in four fractions resulted in excellent local progression-free survivalrates with minimal toxicity in both peripherally and centrally located stage I or recurrent NSCLC.

Author Disclosure: J.Y. Chang, None; P. Balter, None; L. Dong, None; Z. Liao, None; K.M. Bucci, None; M. Jeter, None;M.F. McAleer, None; Q. Yang, None; J.D. Cox, None; R. Komaki, None.

157 Radiographic and Metabolic Response of Solitary Lung Tumors to Image Guided Stereotactic Radiotherapy

K. K. Chao, I. S. Grills, L. L. Kestin, C. O. Wong, A. Suen, J. Wloch, D. Yan, G. Hugo

William Beaumont Hospital, Royal Oak, MI

Purpose/Objective(s): To evaluate the radiographic (Computed Tomography, CT) and metabolic (Positron Emission Tomogra-phy, PET) response of lung tumors to stereotactic lung image-guided radiotherapy (IGRT).

Materials/Methods: 20 patients with solitary lung tumors #5 cm were treated with stereotactic lung IGRT on a prospective phaseII trial at William Beaumont Hospital between 11/2005–10/2006. Target volumes were delineated using a combination of free-breathing CT, 4D CT and PET. Four (T1, n = 13) or 5 (T2/metastatic, n = 7) 12-Gy fractions were prescribed to the PTV edge.Both a CT and PET were obtained for all patients at 6 weeks, 16 weeks, and 12 months post-IGRT. A CT alone was done 6 monthspost-IGRT and every 6 months after 1 year. To assess response, the tumor volume and maximum dimension in 3 planes were mea-sured on follow-up CT scans fused to the initial planning CT. Response Evaluation Criteria in Solid Tumors (RECIST) criteria wereused to assess radiographic response (CR = no measurable tumor; PR = $30% reduction in the sum of the longest diameters). Themaximum standardized uptake value (SUV) on PET was measured and verified with a single nuclear medicine physician. The re-lationship between CT and PET response and the following variables were evaluated: tumor stage, maximum dimension, volume,and IGRT dose.

Results: Median follow-up time was 9.3 mo [range: 3–16 mo]. One patient with significant consolidation obscuring response atweeks 6 and 16 was excluded from analysis. Response results are shown in Table 1. 26% of cases exhibited a radiographic CR ata median time of 6 months, all of which demonstrated a reduction in max SUV to #2.75 (mean 2.0). By 6 months, 87% exhibitedeither a CR or PR. Tumor response appears to continue even beyond 6 to 12 months. Metabolic activity substantially decreasedwithin 6 and 16 weeks post-IGRT and remained low 6–12 months thereafter. Smaller pre-treatment tumor dimensions (p =0.01) and volume (p\0.01) statistically correlated with CR on CT. A single patient treated for a metastasis has clinical evidenceof radiographic/metabolic local progression 12 months post-IGRT. No cases of regional or distant recurrence or death have beenobserved.

Conclusions: Stereotactic lung IGRT using 48–60 Gy in 4–5 fractions exhibited significant radiographic and metabolic responseduring the first 6–16 weeks post-IGRT and effects appear to remain durable beyond 6–12 months. Smaller tumor dimensions andvolume correlated with a greater likelihood of achieving radiographic CR.

Author Disclosure: K.K. Chao, None; I.S. Grills, None; L.L. Kestin, None; C.O. Wong, None; A. Suen, None; J. Wloch, None;D. Yan, None; G. Hugo, None.

158 Provider Volume and Outcomes Following Prostate Brachytherapy

A. B. Chen1,2, A. V. D’Amico2,3, B. A. Neville2, C. C. Earle2

1Harvard Radiation Oncology Program, Boston, MA, 2Dana Farber Cancer Center, Boston, MA, 3Brigham and Women’sHospital, Boston, MA

Purpose/Objective(s): We assessed the relationship between provider volume and outcomes following brachytherapy in a popu-lation-based cohort of men over age 65.