SBRT reirradiation results in limited toxicity. Further research is needed to refine optimal roles for SBRT and intensity-modulated radiotherapy (IMRT) reirradiation.

Introduction: Colorectal cancer (CRC) is the third leading cause of cancer-related death in the U.S. Many patients with CRC develop hepatic metastases as the sole site of metastases. Historical treatment options were limited to resection or conventional radiation therapy. Stereotactic body radiation therapy (SBRT) has emerged as a rational treatment approach. This study reviews our experience with SBRT for patients with liver metastases from CRC. Materials and Methods: Fourteen histologically confirmed hepatic CRC metastases in 11 consecutive patients were identified between November, 2004 and June, 2009 at Georgetown University. All patients underwent CT-based treatment planning; a few also had MRI or PET/CT. All patients had fiducial markers placed under CT guidance and were treated using the CyberKnife system. Treatment response and toxicities were examined; survival and local control were evaluated. Results: Most patients were treated to a single hepatic lesion (n = 8), with a few treated to two lesions (n = 3). Median treatment volume was 99.7 cm3, and lesions were treated to a median BED10 of 49.7 Gy (range: 28–100.8 Gy). Median follow-up was 21 months; median survival was 16.1 months, with 2 year actuarial survival of 25.7%. One year local control was 72%. Among patients with post-treatment imaging, eight had stable disease (80%) and two had progressive disease (20%) at first follow-up. The most common grade 1–2 acute toxicities included nausea and alterations in liver function tests; there was one grade 3 toxicity (elevated bilirubin), and no grade 4–5 toxicities. Discussion: SBRT is safe and feasible for the treatment of limited hepatic metastases from CRC. Our results compare favorably with outcomes from previous studies of SBRT. Further studies are needed to better define patient eligibility, study the role of combined modality treatment, optimize treatment parameters, and characterize quality of life after treatment.

Purpose/objective(s)Stereotactic body radiation therapy (SBRT) is emerging as a minimally invasive alternative to brachytherapy to deliver highly conformal, dose-­escalated radiation therapy (RT) to the prostate. SBRT alone may not adequately cover the tumor extensions outside the prostate commonly seen in unfavorable prostate cancer. External beam radiation therapy (EBRT) with high dose rate brachytherapy boost is a proven effective therapy for unfavorable prostate cancer. This study reports on early prostate-specific antigen and prostate cancer-specific quality of life (QOL) outcomes in a cohort of unfavorable patients treated with intensity-modulated radiation therapy (IMRT) and SBRT boost.Materials/methodsProstate cancer patients treated with SBRT (19.5 Gy in three fractions) followed by fiducial-guided IMRT (45–50.4 Gy) from March 2008 to September 2012 were included in this retrospective review of prospectively collected data. Biochemical failure was assessed using the Phoenix definition. Patients completed the expanded prostate cancer index composite (EPIC)-26 at baseline, 1 month after the completion of RT, every 3 months for the first year, then every 6 months for a minimum of 2 years.ResultsOne hundred eight patients (4 low-, 45 intermediate-, and 59 high-risk) with median age of 74 years completed treatment, with median follow-up of 4.4 years. Sixty-four percent of the patients received androgen deprivation therapy prior to the initiation of RT. The 3-year actuarial biochemical control rates were 100 and 89.8% for intermediate- and high-risk patients, respectively. At the initiation of RT, 9 and 5% of men felt their urinary and bowel function was a moderate to big problem, respectively. Mean EPIC urinary and bowel function and bother scores exhibited transient declines, with subsequent return to near baseline. At 2 years posttreatment, 13.7 and 5% of men felt their urinary and bowel function was a moderate to big problem, respectively.ConclusionAt 3-year follow-up, biochemical control was favorable. Acute urinary and bowel symptoms were comparable to conventionally fractionated IMRT and brachytherapy. Patients recovered to near their baseline urinary and bowel function by 2 years posttreatment. A combination of IMRT with SBRT boost is well tolerated with minimal impact on prostate cancer-specific QOL.

Object. Experience with whole-brain radiation therapy for metastatic tumors in the brain has identified a subset of tumors that exhibit decreased local control with fractionated regimens and are thus termed radioresistant. With the advent of frameless radiosurgery, fractionated radiosurgery (2-5 fractions) is being used increasingly for metastatic tumors deemed too large or too close to crucial structures to be treated in a single session. The authors retrospectively reviewed metastatic brain tumors treated at 2 centers to analyze the dependency of local control rates on tumor radiobiology and dose fractionation.Methods. The medical records of 214 patients from 2 institutions with radiation-naive metastatic tumors in the brain treated with radiosurgery given either as a single dose or in 2-5 fractions were analyzed retrospectively. The authors compared the local control rates of the radiosensitive with the radioresistant tumors after either single-fraction or fractionated radiosurgery.Results. There was no difference in local tumor control rates in patients receiving single-fraction radiosurgery between radioresistant and radiosensitive tumors (p = 0.69). However, after fractionated radiosurgery, treatment for radioresistant tumors failed at a higher rate than for radiosensitive tumors with an OR of 5.37 (95% CI 3.83-6.91, p = 0.032).Conclusions. Single-fraction radiosurgery is equally effective in the treatment of radioresistant and radiosensitive metastatic tumors in the brain. However, fractionated stereotactic radiosurgery is less effective in radioresistant tumor subtypes. The authors recommend that radioresistant tumors be treated in a single fraction when possible and techniques for facilitating single-fraction treatment or dose escalation be considered for larger radioresistant lesions. (http://thejns.org/doi/abs/10.3171/2013.8.JNS122177) KEy wOrdS • brain metastases • local control • radioresistance • stereotactic radiosurgery • oncology 1131Abbreviations used in this paper: IQR = interquartile range; OS = overall survival; WBRT = whole-brain radiation therapy.

ANNs outperform traditional statistical tools and scoring indexes for predicting individual patient prognosis. Their facile implementation, robustness in the presence of missing data, and ability to continuously learn make them excellent choices for use in complicated clinical environments.