Proceedings of the 49th Annual ASTRO Meeting S553

2628 Similar Prognosis for Papillary Serous, Clear Cell and Grade 3 Endometrioid Endometrial Carcinomas–A

Cancer Registry Analysis

K. Albuquerque, M. Liotta-Davis, A. Salhadar, L. Millbrandt, C. Walker, R. Durazo, D. Smith, R. Potkul

Loyola University Medical Center, Maywood, IL

Purpose/Objective(s): Evaluate and compare prognosis of high-risk endometrial carcinomas (HREC)-with different morphol-ogies-papillary serous (PS), clear cell (CC) and grade 3 endometrioId adenocarcinomas (G3) adjusted for tumor, patient and treat-ment prognostic factors.

Materials/Methods: Our tumor registry database was queried for surgically staged HREC with complete data available on pathol-ogy and treatment between 1990 to 2005. The electronic medical records, pathology and radiation records of 116 eligible patientswere reviewed in addition for verification. The end point of the study was overall survival (all-cause mortality), which was verifiedby the social security database. The median follow-up time was 28 months. Associations between prognostic variables and patientcharacteristics were analyzed statistically using the chi-squared and t-test and survival was compared using log-rank statistics andCox proportional hazards regression for multivariate analysis. For purposes of analysis, PS & CC morphologies were grouped to-gether as were FIGO stage 1 & 2 (Early stage) and stage 3 & 4 (Advanced stage) Patients receiving either external beam radiation orbrachytherapy were coded as a single group (RT) and those receiving single or multi-agent chemotherapy were recoded as onegroup (CT). Details of chemotherapy were not analyzed.

Results: For the entire group PS & CC does worse [hazard ratio (HR) = 2.39; p = 0.004]. However, adjusting for age, stage, RT and,CT morphology loses its significance with only stage and age being significant (HR for stage = 2.3; p = 0.05/HR for age = 1.04; p =0.02). For 56 women with advanced (III & IV) stage HREC, on univariate analysis RT is the only factor to improve survival (HR =0.44; p = 0.043) with a relative reduction of death by 56% (Figure 1). Median survival time was 33 vs 18 months and crudemortality was 58% vs 40% favouring RT. CT was more commonly prescribed for this group than early stage yet on univariatesurvival analysis, Age, morphology and CT did not significantly affect outcome. In the multivariate model RT did improve survival(HR = 0.48; 95% CI = 0.16; 1.42) but the effect lost its significance.

Conclusions: G3 endometrial tumors did as poorly as PS and CC when corrected for stage and other characteristics in this series.Given the inherent limitations of our analysis (using tumor registry retrospective data); RT was the only factor in our series to im-prove survival for advanced HREC on univariate analysis. These results indicate that high-risk endometrial tumors should betreated aggressively regardless of morphology. Chemotherapy as given in our series did not add a survival benefit.

Author Disclosure: K. Albuquerque, None; M. Liotta-Davis, None; A. Salhadar, None; L. Millbrandt, None; C. Walker, None;R. Durazo, None; D. Smith, None; R. Potkul, None.

2629 The Minimal Dosimetric Benefit of Breast IMRT as Compared to Using a Small Number of Forward

Planned MLC Segments Does Not Justify the Cost

R. M. Cardinale, J. Steele, D. A. Fein, L. Mao, B. H. Chon

Princeton Medical Center, Princeton, NJ

Purpose/Objective(s): Intensity modulated radiation therapy (IMRT) for breast treatment is increasingly being used because ofthe demonstrated dosimetric and clinical benefits as compared to 2D treatment using open tangent fields and wedges. Most insti-tutions that have the capability to perform IMRT can also perform a more simple method which relies on using a few (less than 5)3D forward planned segmented fields (3DFP). This study was designed to compare the cost/benefit ratio of IMRT with 3DFP fora consecutive patient cohort treated at our institution.

Materials/Methods: CT simulation of the breast was performed on twenty consecutive patients. The planning target volume(PTV) and open tangent field borders were made identical between IMRT and 3DFP plans. Tissue density corrections wereused and the prescription isodose was normalized in each case to cover 95% of the PTV for both methods which employeda ‘‘step and shoot’’ technique on the same planning system. Inverse planned IMRT was performed with PTV coverage, dose ho-mogeneity, lung and heart constraints. 3DFP consisted of less than 5 MLC step-and-shoot fields iteratively designed by experi-enced planners using the same objectives as IMRT. Dose volume histogram analysis of the PTV, heart, and lung wasperformed. Technical costs were tabulated using current Medicare codes.

Results: The median maximum dose (as % of prescribed dose), minimum dose, percent PTV receiving .105% of the prescribeddose (V105), and the maximum dose to which at least 5% of the PTV was irradiated (D05) for IMRT and 3DFP plans were 106%,84%, 3%, 103% and 106%, 80%, 6%, 105% respectively. The heart and lung doses were also very similar for all cases. No patient

S554 I. J. Radiation Oncology d Biology d Physics Volume 69, Number 3, Supplement, 2007

had a significant dosimetric benefit to IMRT. The median number of segments was 8 for IMRT and 4 for 3DFP. The total Medicarereimbursement for a 25 fraction treatment course of IMRT was 3.7 times greater than for 3DFP.

Conclusions: Inverse-planned IMRT for breast tangent field irradiation has minimal dosimetric benefits as compared to 3DFP.IMRT planning time, complexity, Q/A procedures and expense seems to be excessive for most cases. Perhaps varying levels ofIMRT coding- with 3DFP being an example of a more simple form- should be developed for breast and other tumor sites to dif-ferentiate between varying complexities and necessities of ‘‘IMRT’’.

Author Disclosure: R.M. Cardinale, None; J. Steele, None; D.A. Fein, None; L. Mao, None; B.H. Chon, None.

2630 Predictors of Non-Compliance With Radiotherapy Among Patients With Squamous Cell Carcinoma of the

Head and Neck Treated at a Veterans Affairs Hospital

A. Knight1, S. P. Lee1, G. Juillard1, J. Sayre1, J. Abelson1, B. McGibbon1, A. Sadeghi2

1UCLA, Los Angeles, CA, 2West Los Angeles Veterans Administration Hospital, Los Angeles, CA

Purpose/Objective(s): The purpose of this study was to identify patient and treatment characteristics predictive of non-compliancewith radiotherapy among West Los Angeles Veterans Affairs Hospital (WLAVA) patients treated for squamous cell carcinoma ofthe head and neck (SCCHN.) The secondary purpose was to examine the effect of missed days of radiotherapy on the survival ofthese patients.

Materials/Methods: Patients treated with radiotherapy with curative intent for SCCHN from 2000 to 2005 were retrospectivelyidentified. Data collected for each patient included gender, ethnicity, KPS, age, stage, smoking status, alcohol use, other substanceabuse, cohabitation status, presence of a psychiatric diagnosis, distance from home to hospital, type of lodging during treatment,use of IMRT, use of chemotherapy, and primary versus adjuvant therapy. Non-compliance was measured in number of days ofradiotherapy missed, excluding holidays and technical malfunction. Multivariate analysis was performed using patient variablesto identify predictors of non-compliance, as well as overall survival.

Results: 109 patients were identified as meeting the inclusion criteria. 106 patients had sufficient documentation for complete datacollection and analysis. The median number of radiotherapy days missed was two. Patient variables of low KPS, advanced stage,and short distance of the patient’s primary address to the hospital were identified by a stepwise multiple logistic regression analysisas predictive of missing greater than two treatment days, with performance measured by area under the ROC curve 0.73 (95% con-fidence interval 0.64–0.83.) Of these 106 patients, 59 were treated at least two years prior to analysis, all of whom had survivalfollow-up data, and these patients were included in survival analysis. Patient variables of smoking cessation, high KPS, and youngage were identified as predictive of survival at 2 years, with performance measured by area under the ROC curve 0.82 (95% con-fidence interval 0.72–0.93.) In a supplementary analysis, non-compliance was associated with decreased survival at 2 years.

Conclusions: Patient variables of low KPS, advanced stage, and short distance from home were associated with an increased likeli-hood of non-compliance in patients with SCCHN treated with radiotherapy at the WLAVA. These findings are especially relevantgiven the large proportion of WLAVA patients referred for radiotherapy from outside facilities, who have a primary address that isa long distance from the hospital.

Author Disclosure: A. Knight, None; S.P. Lee, None; G. Juillard, None; J. Sayre, None; J. Abelson, None; B. McGibbon, None;A. Sadeghi, None.

2631 Patterns of use of Intensity-Modulated and Conventional Radiotherapy Among Radiation Oncologists

Who Treat Older Men With Non-Metastatic Prostate Cancer

J. E. Bekelman1, M. J. Zelefsky1, T. L. Jang1, E. M. Basch1, E. Elkin1, B. D. Smith2, Y. Liu1, D. Schrag1

1Memorial Sloan-Kettering Cancer Center, New York, NY, 2Lackland Air Force Base, San Antonio, TX

Purpose/Objective(s): Technology for the delivery of external beam radiotherapy (EBRT) has evolved from conventional(CONVRT) to 3D conformal (3DCRT) to intensity-modulated (IMRT) radiotherapy. Practice guidelines have recommended3DCRT for the treatment of non-metastatic prostate cancer since 2000. Intensity-modulated radiotherapy (IMRT) has further im-proved clinical outcomes. Yet, patterns of physician use of these technologies have been understudied.

Materials/Methods: Using data from the linked Surveillance, Epidemiology, and End Results (SEER)-Medicare program, weevaluated the use of these 3 external beam EBRT technologies as delivered by 843 radiation oncologists. These physicians treated10,563 patients age 65 or older diagnosed from 2000 to 2002.

Using the physician as the unit of analysis (N = 843), we first examined the association between physician characteristics andtheir propensity to deliver CONVRT. Second, we examined their propensity to deliver IMRT. Physician characteristics were ob-tained by linkage to the AMA Masterfile and included practice location (by state), residency training era (before 1980, 1980–1990,after 1990), gender, board certification, teaching affiliation, and state certificate of need status. We adjusted each analysis by theproportion of each physician’s patients who were 70 years or older, black, Hispanic, stage III/IV(M0), Gleason 8–10, had comor-bidity, and who resided in rural or low income areas.

Results: Overall, 350 (42%) physicians delivered CONVRT to 1,558 patients, 715 (85%) physicians delivered 3DCRT to 7,689patients, and 250 (30%) physicians delivered IMRT to 1,316 patients. More than one technology was used by 398 (47%) physi-cians. Practice patterns were in flux over the study period: Between 2000 and 2002, the proportion of treating physicians usingCONVRT went from 41% to 23%, 3DCRT from 81% to 75%, and IMRT from 4% to 37%.

After adjusting for patient mix, a higher propensity to deliver CONVRT was significantly associated only with earlier trainingeras and practice location. Conversely, a higher propensity to deliver IMRT was significantly associated only with more recenttraining eras, practice location, and male physician gender. The Figure shows substantial variation in physician use of IMRTand CONVRT by practice location.

Conclusions: From 2000 to 2002, the majority of physicians used 3DCRT, many adopted IMRT and a substantial proportion con-tinued to use CONVRT. Uneven adoption of advanced technology and lagging abandonment of inferior technology underscore thechallenges of technology dissemination and potential disparities in care.