K. Clarke

Stereotactic body radiotherapy (SBRT) for non-small cell lung cancer (NSCLC): Is FDG-PET a predictor of outcome?

BACKGROUND AND PURPOSE Distant metastases are the dominant mode of failure after stereotactic body radiotherapy (SBRT) for early-stage non-small cell lung cancer (NSCLC). The primary study objective was to evaluate if the maximum standardized uptake value (SUV(max)) on pre-treatment FDG-PET/CT predicted clinical outcomes. Secondary objectives were to correlate 3-month post-SBRT SUV(max) and change in SUV(max) with outcomes. MATERIALS AND METHODS Consecutive patients with medically inoperable early-stage NSCLC and an FDG-PET/CT scan before (n=82) and 3 months after (n=62) SBRT. RESULTS Median follow up was 2 years. On univariate analysis baseline SUV(max) predicted for distant failure (p=0.0096), relapse free survival (RFS) (p=0.037) and local failure (p=0.044). On multivariate analysis baseline SUV(max) predicted for RFS (p=0.037). Baseline SUV(max) of above 5 was the most statistically significant cut off point for predicting distant failure (p=0.0002). Baseline SUV(max) ≥4.75 (median) was correlated with a higher risk of distant failure (p=0.012) and poorer RFS (p=0.04). Patients with a post-SBRT SUV(max) ≥2 and a reduction of <2.55 had a significantly higher rate of distant failure. CONCLUSIONS Pre-SBRT SUV(max) on FDG-PET/CT correlated most strongly with distant failure. A cut off of ≥5 was the most significant. Post-SBRT SUV(max) ≥2 and a reduction of <2.55 were associated with a higher risk of distant failure.

Spontaneous regression in advanced non-small cell lung cancer.

Locally advanced lung cancer, if untreated, typically progresses although the rapidity of progression may vary. The authors report the case of an 84-year-old woman who presented with radiologically progressive, biopsy proven stage IIIB (T2N3) squamous cell carcinoma in the left lower lobe of the lung. Her disease was too advanced for curative treatment and in view of the lack of symptoms to palliate, she received no anticancer treatment. In follow-up, her tumour was noted to spontaneously regress in size on serial chest x-rays. Eight months after biopsy, restaging CT showed complete resolution of the enlarged biopsy proven mediastinal and hilar lymph nodes and significant regression of the primary tumour. She remains clinically well.

Predicting Radiation Esophagitis Using 18F-FDG PET During Chemoradiotherapy for Locally Advanced Non-Small Cell Lung Cancer.

Introduction: Treatment of locally advanced non–small cell lung cancer with chemoradiotherapy (CRT) is limited by development of toxicity in normal tissue, including radiation esophagitis (RE). Increasingly, 18F‐fluorodeoxyglucose (FDG) positron emission tomography (PET) is being used for adaptive planning. Our aim was to assess changes in esophageal FDG uptake during CRT and relate the changes to the onset and severity of RE. Methods: This prospective study in patients with stage II–III non–small cell lung cancer involved serial four‐dimensional computed tomography and PET scans during CRT (60–74Gy). RE was recorded weekly using the Common Terminology Criteria for Adverse Events (v4.0), and imaging was performed at weeks 0, 2, 4, and 7. Changes in the esophaguss peak standard uptake value (SUVpeak) were analyzed for each time point and correlated with grade of RE using the Wilcoxon rank‐sum test. The volume of esophagus receiving 50 Gy (V50) and volume of esophagus receiving 60 Gy (V60) were correlated with the development of RE, and the C‐statistic (area under the curve [AUC]) was calculated to measure predictivity of grade 3 RE. Results: RE developed in 20 of 27 patients (74%), with grade 3 reached in 6 (22%). A significant percentage increase in SUVpeak in the patients with RE was noted at week 4 (p = 0.01) and week 7 (p = 0.03). For grade 3 RE, a significant percentage increase in SUVpeak was noted at week 2 (p = 0.01) and week 7 (p = 0.03) compared with that for less than grade 3 RE. Median V50 (46.3%) and V60 (33.4%) were significantly higher in patients with RE (p = 0.04). The AUC measurements suggested that the percentage change in SUVpeak at week 2 (AUC = 0.69) and V50 (AUC = 0.67) and V60 (AUC = 0.66) were similarly predictive of grade 3 RE. Conclusions: Serial FDG‐PET images during CRT show significant increases in SUVpeak for patients in whom RE develops. The changes at week 2 may predict those at risk for the development of grade 3 RE and may be informative for adaptive planning and early intervention.

Serial 4DCT/4DPET imaging to predict and monitor response for locally-advanced non-small cell lung cancer chemo-radiotherapy

BACKGROUND AND PURPOSE A FDG-PET/CT image feature with optimal prognostic potential for locally-advanced non-small cell lung cancer (LA-NSCLC) patients has yet to be identified, and neither has the optimal time for FDG-PET/CT response assessment; furthermore, nodal features have been largely ignored in the literature. We propose to identify image features or imaging time point with maximal prognostic power. MATERIALS AND METHODS Consecutive consenting patients with LA-NSCLC receiving curative intent CRT were enrolled. 4DPET/4DCT scans were acquired 0, 2, 4, and 7 weeks during IMRT treatment. Eleven image features and their rates of change were recorded for each time point and tested for each of the possible outcome 2 years post CRT using the Kaplan-Meier method. RESULTS 32 consecutive patients were recruited, 27 completing all scans. Restricting analysis to 4DPET/4DCT features and rates of change with p < 0.005, several volume-based features and their rates of change reached significance. Image features involving nodal disease were the only ones associated with overall survival. CONCLUSIONS Several 4DPET/CT features and rates of change can reach significant association (p < 0.005) with outcomes, including overall survival, at many time points. The optimal time for adaptive CRT is therefore not constrained uniquely on imaging.