H. Yoo

Stereotactic body radiation therapy boost in locally advanced pancreatic cancer.

PURPOSE To investigate the clinical application of a stereotactic body radiation therapy (SBRT) boost in locally advanced pancreatic cancer patients with a focus on local efficacy and toxicity. METHODS AND MATERIALS We retrospectively reviewed 30 patients with locally advanced and nonmetastatic pancreatic cancer who had been treated between 2004 and 2006. Follow-up duration ranged from 4 to 41 months (median, 14.5 months). A total dose of 40 Gy was delivered in 20 fractions using a conventional three-field technique, and then a single fraction of 14, 15, 16, or 17 Gy SBRT was administered as a boost without a break. Twenty-one patients received chemotherapy. Overall and local progression-free survival were calculated and prognostic factors were evaluated. RESULTS One-year overall survival and local progression-free survival rates were 60.0% and 70.2%, respectively. One patient (3%) developed Grade 4 toxicity. Carbohydrate antigen 19-9 response was found to be an independent prognostic factor for survival. CONCLUSIONS Our findings indicate that a SBRT boost provides a safe means of increasing radiation dose. Based on the results of this study, we recommend that a well controlled Phase II study be conducted on locally advanced pancreatic cancer.

Robotic system-based fractionated stereotactic radiotherapy in locally recurrent nasopharyngeal carcinoma

PURPOSE We reviewed survival, local control, and toxicity in patients with locally recurrent nasopharyngeal carcinoma (NPC) who had been treated with fractionated stereotactic radiotherapy (FSRT). MATERIALS AND METHODS Between June 2002 and March 2008, we retrospectively reviewed 35 patients with locally recurrent NPC treated using FSRT with CyberKnife. Gross tumor volumes ranged from 2.6 to 64.0 ml (median, 7.9 ml). Radiation doses were prescribed at the isodose line (75-84% of the maximum dose; median, 80%). The prescribed dose of FSRT ranged from 24 to 45 Gy (median, 33 Gy) in three or five fractions. RESULTS The overall survival (OS) rate, local failure-free survival (LFFS) rate, and disease progression-free survival (DPFS) rate at 5 years were 60%, 79%, and 74%, respectively. Twenty-three patients achieved complete response after FSRT. Only T stage at recurrence was an independent prognostic factor for OS and DPFS. Five patients exhibited severe late toxicity (Grade 4 or 5). CONCLUSIONS With regard to OS and LFFS, our study provided favorable outcomes. The incidence of severe late toxicities was acceptable in our study. FSRT would be considered as the alternative treatment of choice in re-irradiation for locally recurrent NPC.

Stereotactic body radiotherapy for oligo-recurrence within the nodal area from colorectal cancer

Recurrence of colorectal cancer (CRC) often presents as solitary metastases, oligometastases or oligo-recurrence. Surgical resection became the preferred treatment for patients with CRC lung and hepatic metastases. However, surgical treatment for oligo-recurrence within nodal area is not a widely accepted treatment due to due to their relative rarity and high postoperative morbidity. Stereotactic body radiotherapy (SBRT) is one of the emerging radiation treatment techniques in which a high radiation dose can be delivered to the tumor. High-dose SBRT can ablate the tumor with an efficacy similar to that achieved with surgery, especially for small tumors. However, there have been very few studies on SBRT for oligo-recurrence within nodal area, although several studies have evaluated the role of SBRT in the treatment of liver and lung metastases from CRC. This article reviews the current clinical status of and treatment methods for oligo-recurrence within nodal area from CRC, with particular emphasis on SBRT.

Salvage stereotactic body radiotherapy for locally recurrent uterine cervix cancer at the pelvic sidewall: Feasibility and complication.

To determine the feasibility of stereotactic body radiotherapy (SBRT) in patients with pelvic sidewall recurrence of uterine cervical cancer after radical hysterectomy or definitive radiotherapy.

Stereotactic Body Radiotherapy for Oligometastases Confined to the Para-Aortic Region: Clinical Outcomes and the Significance of Radiotherapy Field and Dose

We retrospectively reviewed 88 patients with oligometases in the para-aortic region from any controlled primary tumor site who were treated with stereotactic body radiotherapy (SBRT). The 5-year local control, disease-free survival, and overall survival rates were 83%, 31%, and 41%, respectively. A 90% tumor-control probability was predicted at a biological effective dose of 90 Gy. Severe gastrointestinal toxicities (grade ≥3) were observed in 2 of 88 patients (1%). The results of this study are limited by the retrospective nature of the study but could serve as the background and rationale for future prospective trials on SBRT-based treatment for oligometastses.

Radiofrequency ablation versus stereotactic body radiotherapy for small hepatocellular carcinoma: a Markov model‐based analysis

The aim of this study is to compare radiofrequency ablation (RFA) with stereotactic body radiotherapy (SBRT) for hepatocellular carcinomas (HCC) smaller than 3 cm. A Markov cohort model was developed to simulate a cohort of patients aged 60–65 years with small HCCs who had undergone either RFA or SBRT and were followed up over their remaining life expectancy. The inclusion criteria were: (1) HCC ≤3 cm in diameter with ≤ 3 nodules; (2) absence of extrahepatic metastasis or portal/hepatic vein invasion; (3) Child‐Pugh Class A or B. Twenty thousand virtual patients were randomly assigned to undergo RFA or SBRT. Predicted life expectancy was 6.452 and 6.371 years in the RFA and SBRT groups, respectively. The probability distributions of the expected overall survival were nearly identical. The 95% confidence intervals were 6.25–6.66 and 6.17–6.58 years for RFA and SBRT, respectively. The difference between RFA and SBRT was insignificant (P = 0.2884). Two‐way sensitivity analysis demonstrated that if the tumor is 2–3 cm, SBRT is the preferred treatment option. Our Markov model has shown that expected overall survival of SBRT is nearly identical to RFA in HCCs smaller than 3 cm, but SBRT may have an advantage for tumors 2 cm and larger. A randomized trial is required to confirm these findings.

EP-1499: GEANT4 Monte-carlo simulations for the luminescence properties of Gd2O3:Eu scintillator

Results: Response reproducibility, short term stability and linearity with dose are those typical of ionization chamber based detectors. Maximum deviation of approximately 1.5% in sensitivity was observed in the range 0.1 – 2.5 mGy/pulse. For all different clinical evaluations, the array was found to be in very good agreement with the reference detectors. Dose distributions with steep gradients are very well defined due to the 4 mm spatial resolution and to the limited effect of volume averaging. Additionally, good agreement was observed between the expected dose from TPS and the measurements. Moreover, the detector insensitivity on dose per pulse in conjunction with the low energy dependence typical of ionization chambers lead to high performance even when therapy beams feature extremely modulated dose rates.