WE-E-BRB-05: A Novel Detector Dose Calculation Model for in Vivo Delivery Verification of IMRT Treatments.

PURPOSE: Exit 2D detectors are widely used in clinics as a tool for pre- treatment field verification. It is desired to have accurate modeling of the detector dose for each IMRT plan with patient geometry for in-vivo delivery verification. We propose a novel hybrid of model and measurement based methods to estimate the detector dose using the information from TPS and plan/verification CT. METHODS: Our approach is based on the generalized equivalent field size (GEFS) method. It requires two commissioning tables for various square fields (l×l, 2×2, …40×40): the percent depth dose (PDD) table and the detector correction factor (DDCF) table. PDDs are retrieved from the treatment planning system (TPS), and DDCFs are reconstructed from measurement with various field sizes and air gaps (from 5 cm to 50 cm). GEFS models the detector point dose as the superposition of annular contribution of the fluence map, which is retrieved from the TPS. Correction on the radiological path length is calculated through ray-tracing the patient CT. Corrections on the air gap between the couch and detector and detector response are applied via table lookup on PDD and DDCF. RESULTS: We validated the proposed method using TPS with extended geometry and direct clinic measurements for both regular and IMRT fields, various phantom and patient geometry. For all calculations, more than 98% of pixels pass the gamma index with criteria of 3%, 3mm. Each calculation took only a few seconds on a single PC. CONCLUSIONS: We proposed a novel detector dose calculation method that can be applied for arbitrary IMRT field and arbitrary patient geometry. The calculation is simple and fast and when compared with detector measurement during IMRT treatment, makes in- vivo delivery verification and dose reconstruction feasible.

Clinical outcome and prognosis of patients with inflammatory breast cancer.

This report analyzes clinical factors affecting outcome in 26 patients with inflammatory breast cancer. Peau d'orange was the most common clinical finding at diagnosis (65%). A palpable breast mass (PBM) was noted in 65% with axillary lymph node involvement in 81% of patients. Eighteen patients were staged as stage IIIB and eight as stage IV. Initial metastases included supraclavicular nodes (five of eight), bones (one of eight), skin (one of eight), and liver (one of eight). All patients were treated with neoadjuvant chemotherapy (cyclophosphamide, doxorubicin, and fluorouracil, 18 patients; other, 8 patients). Partial response was the best clinical response attained in 38% of patients. Only one patient was treated with total mastectomy after neoadjuvant chemotherapy, and 19 patients received radiotherapy followed (2 patients) or not (17 patients) by mastectomy. The progression rate in stage IIIB patients was 78%, with distant sites of progression in 93% of patients and only 7% with local progression. Mean time-to-progression was 13 months (Kaplan-Meier estimates of 45% and 11% at 24 and 48 months, respectively). The median overall survival (OS) value of the entire population was 13.2 months (Kaplan-Meier estimates at 24 and 48 months of 21% and 12.5%). By Kaplan-Meier method and log-rank test, a better OS was correlated with stage IIIB (p = 0.002), a PBM at diagnosis (p = 0.01), and a favorable response to initial chemotherapy (p = 0.03). Our results confirm the better clinical outcome of patients with stage IIIB and PBM at diagnosis. They also support the role for combined treatment as the best modality approach for this disease. However, overall prognosis remained poor, with recurrence and death resulting from the disease.

Oral ftorafur plus intramuscular thiotepa as adjuvant chemotherapy in patients with breast cancer.

In this study, we evaluated the safety and efficacy of a combination of oral ftorafur administered together with intramuscular thiotepa as adjuvant chemotherapy for "early" breast cancer patients. A total of 30 patients with operated breast cancer were treated with 500 mg/m2 oral ftorafur for 10 consecutive days plus 20 mg/m2 intramuscular (im) administered thiotepa on d 1 and 8 every 28 d adjuvant chemotherapy. Eleven patients were premenopausal and 19 were postmenopausal, with a median age of 53 yr. The total number of cycles delivered was 259 (median: 10 cycles per patient). Toxicity was low and usually consisted of leukopenia WHO grade I-II (14%) and neutropenia grade I-II (6%). Gastrointestinal toxicity was minimal. The 5-yr disease-free survival and overall survival were 55% and 84%, respectively. Relapse occurred as bone metastases (50%), local recurrence (25%), and liver (17%) and brain (8%) metastases. Our preliminary data showed that oral ftorafur and im thiotepa is a well-tolerated regimen and could be a useful alternative to the intravenous parenteral route as adjuvant treatment for early breast cancer. Randomized trials are needed to assess the possible advantage of this regimen over intravenous schedules.

Heterogeneous distribution of tumor blood supply affects the response to chemotherapy in patients with head and neck cancer.

OBJECTIVE: To evaluate if the heterogeneous distribution of tumor blood supply affects the response to chemotherapy in patients with head and neck cancer. METHODS: We treated 25 stage III/IV patients with an intraarterial cisplatinum-bleomycin regimen. Prior to treatment, a blue dye was injected directly to tumors through the catheter. Well-stained areas were considered as profusely perfused areas whereas poorly stained areas were considered as poorly perfused areas. Biopsies of both areas of each tumor were taken prior to and after the treatment and the histopathological response was evaluated with the following grading: I, tumor disappearance; II, destruction of some tumor nests; III, no changes. RESULTS: Grade I responses were attained in 13/25 (52%) of profusely perfused areas against 1/25 (4%) of poorly perfused areas (p < 0.001). Moreover, there were significant differences (p < 0.001) in the overall responses: 21/25 (84%) in the profusely perfused areas versus 7/25 (28%) in the poorly perfused areas; and in grade III responses (4/25, 16% vs. 18/25, 72%). To determine a possible correlation between the histopathological responses obtained in profusely perfused and in poorly perfused areas of each tumor, we then calculated the Kendall's tau-b statistics, obtaining a tau value of 0.279 (p = 0.145). This data indicated that histopathological responses to chemotherapy of profusely perfused and poorly perfused areas were independent in each tumor. CONCLUSIONS: Heterogeneity in the distribution of tumor blood supply affects the response to chemotherapy by influencing the intratumoral delivery of therapeutic agents. After the administration of effective doses of anticancer drugs to a tumor, cells in profusely perfused areas receive enough to destroy them while cells in the poorly perfused areas are exposed to lower drug concentrations and, therefore, survive. This phenomenon could explain in part the difficulty in the treatment of human solid tumors.

Rescue FK506 early conversion for refractory rejection after pediatric liver transplantation: experience in 20 children.

Tacrolimus (FK506) is an effective and relatively safe novel immunosuppressant able to revert refractory rejection after pediatric liver transplantation (LTx). Between April 1993 and October 1996, 20 pediatric patients were converted to tacrolimus for biopsy-proven, steroid-resistant liver rejection. The mean follow-up was 18 months. The median time from LTx to switch was 20 days. Tacrolimus was administered per os at a mean dosage of 0.23 mg/kg per day to maintain median blood levels of 10.8 ng/ml at 1 week and 9.2 ng/ml at 1 year from the switch. Of the 20 patients, 15 are alive and they all recovered from rejection without the need of OKT3 after conversion. The major causes of death were: one multiorgan failure, two infections (cytomegalovirus Aspergillus), one bowel perforation, and one posttransplant lymphoproliferative disease. One patient experienced late side effects and was reconverted to cyclosporine when she was already rescued from hepatic allograft rejection. The results confirm that an earlier conversion to tacrolimus should be recommended after pediatric liver transplantation in order to revert hepatic allograft rejection with the best safety profile.