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

Proceedings of the 49th Annual ASTRO Meeting

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 morphologies-papillary serous (PS), clear cell (CC) and grade 3 endometrioId adenocarcinomas (G3) adjusted for tumor, patient and treatment prognostic factors. Materials/Methods: Our tumor registry database was queried for surgically staged HREC with complete data available on pathology and treatment between 1990 to 2005. The electronic medical records, pathology and radiation records of 116 eligible patients were reviewed in addition for verification. The end point of the study was overall survival (all-cause mortality), which was verified by the social security database. The median follow-up time was 28 months. Associations between prognostic variables and patient characteristics were analyzed statistically using the chi-squared and t-test and survival was compared using log-rank statistics and Cox proportional hazards regression for multivariate analysis. For purposes of analysis, PS & CC morphologies were grouped together as were FIGO stage 1 & 2 (Early stage) and stage 3 & 4 (Advanced stage) Patients receiving either external beam radiation or brachytherapy were coded as a single group (RT) and those receiving single or multi-agent chemotherapy were recoded as one group (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 crude mortality was 58% vs 40% favouring RT. CT was more commonly prescribed for this group than early stage yet on univariate survival 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 improve survival for advanced HREC on univariate analysis. These results indicate that high-risk endometrial tumors should be treated 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 of the demonstrated dosimetric and clinical benefits as compared to 2D treatment using open tangent fields and wedges. Most institutions 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 for a 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 were used and the prescription isodose was normalized in each case to cover 95% of the PTV for both methods which employed a ‘‘step and shoot’’ technique on the same planning system. Inverse planned IMRT was performed with PTV coverage, dose homogeneity, lung and heart constraints. 3DFP consisted of less than 5 MLC step-and-shoot fields iteratively designed by experienced planners using the same objectives as IMRT. Dose volume histogram analysis of the PTV, heart, and lung was performed. 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 prescribed dose (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

S553