K.A. Kumar

Image-guided radiation therapy for prostate cancer: A computed tomography–based assessment of fiducial marker migration between placement and 7 days

PURPOSE This study was conducted to determine whether clinically significant fiducial marker migration occurs immediately after prostatic implantation. METHODS AND MATERIALS One hundred patients with transperineal (n = 39) or transrectal (n = 61) placement of 3 gold fiducial markers underwent computed tomography scans on day 0 (after placement) and day 7 (at radiation planning). Each marker was marked as a point of interest in a treatment planning system. An automated point-based algorithm was then used to coregister the day 0 and day 7 images by matching the markers through rigid translations and rotations. The mean distance between fiducial pairs (d¯) was recorded to assess the degree of seed migration. Prostate contours were delineated, and the day 0 prostate volumes were uniformly expanded by 1, 3, and 5 mm. The percentage of the day 7 prostate volume covered by each day 0 prostate with expansion was calculated to assess whether prostate contours, if performed on day 0, would adequately cover the prostate on day 7. RESULTS The average d¯ for all patients was 0.78 ± 0.45 mm; only 1 patient had d¯ > 2 mm. Placement technique, hormonal therapy, prostate size, and marker distance from the capsule were not associated with d¯ (P > .05). The mean percentages of day 7 prostate volumes covered by the day 0 prostate plus 1, 3, and 5 mm were 98.3%, 99.8%, and 100%, respectively. With an expansion of 3 mm, 98% of men had >95% of day 0 volume covered; with an expansion of 5 mm, 100% of men had 100% of the day 0 volume covered. CONCLUSIONS There is minimal change in the relative positions of fiducial markers (average d¯ < 1.0 mm) 1 week after placement. A 1- to 3-mm expansion would account for the variation in seed position for the vast majority of cases. These results suggest that planning could be performed on the day of implantation without adverse consequence.

Stereotactic Body Radiotherapy in the Treatment of Spinal Metastases

Patients with metastatic disease including polymetastatic, oligometastatic, and oligorecurrent spinal lesions have extended life expectancy secondary to improvements in systemic agents, and thus require durable local control of spine metastases. Stereotactic body radiotherapy (SBRT), which uses highly conformal treatment planning techniques coupled with image-guided technology, has enabled the safe delivery of tumor-ablative doses of radiotherapy. The NOMS decision framework has been developed as a tool to aid in the determination of the optimal treatment of spinal metastases, incorporating radiosurgery, separation surgery, stabilization techniques, and conventional radiation. Tumor radiosensitivity is critical in determining appropriateness of radiosurgery. In general, higher radiation doses provide significant, more durable tumor control, whether single-fraction or hypofractionated regimens are used. Spine SBRT can provide a high likelihood of durable tumor control with very low rates of serious toxicity, and careful attention should be given to dose constraints of organs at risk. Here, we review the indications for spine SBRT via the NOMS decision framework and provide practical information to the radiation oncologist regarding spine radiosurgery.

Cost-effectiveness of radiation and chemotherapy for high-risk low-grade glioma

Background The addition of procarbazine, lomustine, vincristine (PCV) chemotherapy to radiotherapy (RT) for patients with high-risk (≥40 y old or subtotally resected) low-grade glioma (LGG) results in an absolute median survival benefit of over 5 years. We evaluated the cost-effectiveness of this treatment strategy. Methods A decision tree with an integrated 3-state Markov model was created to follow patients with high-risk LGG after surgery treated with RT versus RT+PCV. Patients existed in one of 3 health states: stable, progressive, or dead. Survival and freedom from progression were modeled to reflect the results of RTOG 9802 using time-dependent transition probabilities. Health utility values and costs of care were derived from the literature and national registry databases. Analysis was conducted from the health care perspective. Deterministic and probabilistic sensitivity analysis explored uncertainty in model parameters. Results Modeled outcomes demonstrated agreement with clinical data in expected benefit of addition of PCV to RT. The addition of PCV to RT yielded an incremental benefit of 4.77 quality-adjusted life-years (QALYs) (9.94 for RT+PCV vs 5.17 for RT alone) at an incremental cost of

Prognostic Value of Pretreatment FDG-PET Parameters in High-dose Image-guided Radiotherapy for Oligometastatic Non–Small-cell Lung Cancer

48635 (

A Pilot Study Evaluating the Use of Dynamic Contrast-Enhanced Perfusion MRI to Predict Local Recurrence After Radiosurgery on Spinal Metastases

188234 for RT+PCV vs

Radiation Therapy for Colorectal Liver Metastases

139598 for RT alone), resulting in an incremental cost-effectiveness ratio of

The Role of Stereotactic Radiosurgery in the Reirradiation of Metastatic Spinal Tumors

10186 per QALY gained. Probabilistic sensitivity analysis demonstrates that within modeled distributions of parameters, RT+PCV has 99.96% probability of being cost-effectiveness at a willingness-to-pay threshold of

Tracheal Diverticulum Following Paratracheal Hypofractionated Radiotherapy in the Setting of Prior and Subsequent Bevacizumab.

100000 per QALY. Conclusion The addition of PCV to RT is a cost-effective treatment strategy for patients with high-risk LGG.

Fractionation of palliative radiotherapy in metastatic breast cancer: Selection and survival.

Micro‐Abstract: We conducted a retrospective study of oligometastatic non–small‐cell lung cancer patients who underwent pretreatment fluorodeoxyglucose positron emission tomography imaging and received high‐dose radiotherapy to all sites of disease. A greater metabolic tumor burden was associated with shorter overall survival not explained by the number of lesions or maximum standardized uptake value. Biomarkers might help to better select oligometastatic patients for locally ablative therapy. Background: Emerging data support aggressive local treatment of oligometastatic non–small‐cell lung cancer (NSCLC) patients. We sought to determine whether the metabolic burden of disease found by fluorodeoxyglucose positron emission tomography at the time of high‐dose radiotherapy (RT) for oligometastatic NSCLC can serve as a prognostic biomarker. Materials and Methods: We conducted a retrospective cohort study of 67 RT treatment courses in 55 patients with oligometastatic NSCLC who had undergone high‐dose RT to all sites of active disease at our institution. The metabolic tumor volume, total lesion glycolysis (TLG), and maximum standardized uptake value of all lesions were measured on the pretreatment fluorodeoxyglucose positron emission tomography scans. Cox regression analysis was used to assess the influence of imaging and clinical factors on overall survival (OS). Results: On univariate analysis, a greater metabolic tumor volume and TLG were predictive of shorter OS (hazard ratio of death, 2.42 and 2.14, respectively; P = .009 and P = .004, respectively). The effects remained significant on multivariate analysis. Neither the maximum standardized uptake value nor the number of lesions was significantly associated with OS. Patients within the highest quartile of TLG values (> 86.8 units) had a shorter median OS than those within the lower 3 quartiles (12.4 vs. 30.1 months; log‐rank P = .014). Conclusion: The metabolic tumor burden was prognostic of OS and might help to better select oligometastatic NSCLC patients for locally ablative therapy.

Survival comparison of patients treated with one versus five fraction palliative radiotherapy.

Purpose: Dynamic contrast-enhanced magnetic resonance imaging offers noninvasive characterization of the vascular microenvironment and hemodynamics. Stereotactic radiosurgery, or stereotactic body radiation therapy, engages a vascular component of the tumor response which may be detectable using dynamic contrast-enhanced magnetic resonance imaging. The purpose of this study is to examine whether dynamic contrast-enhanced magnetic resonance imaging can be used to predict local tumor recurrence in patients with spinal bone metastases who undergo high-dose radiotherapy with stereotactic radiosurgery. Materials and Methods: We conducted a study of 30 patients with spinal metastases who underwent dynamic contrast-enhanced magnetic resonance imaging before and after radiotherapy. Twenty patients received single-fraction stereotactic radiosurgery (24 Gy), while 10 received hypofractionated stereotactic radiosurgery (3-5 fractions, 27-30 Gy total). Kaplan-Meier analysis was used to estimate the actuarial local recurrence rates. Two perfusion parameters (Ktrans: permeability and Vp: plasma volume) were measured for each metastasis. Percentage change in parameter values from pre- to posttreatment was calculated and compared. Results: At 20-month median follow-up, 5 of the 30 patients had pathological evidence of local recurrence. One- and 3-year actuarial local recurrence rates were 24% and 44% for the hypofractionated stereotactic radiosurgery cohort versus 5% and 16% for the single-fraction stereotactic radiosurgery cohort (P = .20). The average change in Vp and Ktrans for patients without local recurrence versus those with local recurrence was −76% and −66% versus +28% and −14% (P < .01 for both). With a cutoff point of −20%, Vp had a sensitivity, specificity, positive predictive value, and negative predictive value of 100%, 98%, 91%, and 100%, respectively, for the detection of local recurrence following high-dose radiotherapy. Using this definition, dynamic contrast-enhanced magnetic resonance imaging identified local recurrence up to 18 months (mean [standard deviation], 6.6 [6.8] months) earlier than standard magnetic resonance imaging. Conclusions: We demonstrated that changes in perfusion parameters, particularly Vp, after high-dose radiotherapy to spinal bone metastases were predictive of local tumor recurrence. These changes predicted local recurrence on average >6 months earlier than standard imaging did.