Maximum standardized uptake value at pre-treatment PET in estimating lung cancer progression after stereotactic body radiotherapy

The prognostic value of 18F-FDG PET/CT taken immediately after completion of radiotherapy for lung cancer treated with concurrent chemoradiotherapy: A pilot study

PURPOSE

The prognostic value of F-18 fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) taken immediately after completion of radiotherapy in lung cancer patients is not well known. The purpose of this study is to assess the prognostic value of PET/CT taken immediately after completion of radiotherapy in lung cancer patients.

MATERIALS AND METHODS

Patients with primary lung cancer planned to undergo concurrent chemoradiotherapy were enrolled. Patients underwent PET/CT scans at 3 time points: before radiotherapy, within 24hours of completing radiotherapy (im-PET/CT), and 2-9 months after radiotherapy (post-PET/CT). Maximum standardized uptake value (SUV_max) was obtained. A post-PET/CT-SUV_max cut-off of 2.5 was determined as radiotherapy success.

RESULTS

Nineteen patients were enrolled. im-PET/CT-SUV_max for patients in the high post-PET/CT-SUV_max group was significantly higher than that of the low group (P=0.004). Receiver operator curve analysis indicated that im-PET/CT-SUV_max of 4.35 was an optimal cut-off value to discriminate between the two groups. Multivariable analysis showed that a high im-PET/CT-SUV_max was significantly associated with a high post-PET/CT-SUV_max (P=0.003).

CONCLUSION

PET/CT-SUV_max taken immediately following radiotherapy was associated with that evaluated 2-9 months after radiotherapy.

Necrosis on pre-radiotherapy 18F-FDG PET/CT is a predictor for complete metabolic response in patients with non-small cell lung cancer

To investigate necrosis on pre-radiotherapy (RT) 18F-FDG PET/CT (PETNECROSİS) as a predictor of complete metabolic response (CMR) in patients with non-small cell lung cancer (NSCLC).We evaluated patients with inoperable stage I-III NSCLC who underwent pre- and post-radiotherapy 18F-FDG PET/CT. The relationship between CMR and PETNECROSIS, SUVmax, gross tumor volume calculated with 18F-FDG PET/CT (GTVPET-CT), tumor size, histology, metabolic tumor volume (MTV), and RT dose was assessed using logistic regression analysis. To evaluate necrosis on 18F FDG PET/CT, we drew a region of interest (ROI) in the area showing visually very low/or no fluorodeoxyglucose (FDG) uptake on PET images. If the SUVmax was lower than the blood pool SUVmax and showed significantly lower attenuation (10-30 Hounsfield units [HU]) from the surrounding tissue on non-intravenous contrast-enhanced low-dose correlative CT, we defined it as necrotic (PETNECROSİS).Fifty-three patients were included in this study. The mean age was 68.1 ± 9.8 years. Twenty-one patients had adenocarcinoma, and 32 had squamous cell carcinoma. All parameters were independent of histologic status. Multivariate logistic regression analysis showed that SUVmax ≤11.6 vs >11.6, (P = .003; OR, 7.670, 95CI%: 2.013-29.231) and PETNECROSİS absence/presence were independent predictors for CMR (P = .028, OR: 6.704, 95CI% 1.214-30.394).The necrosis on 18F FDG PET/CT and SUVmax > 11.6 could be an imaging marker for the complete metabolic response after definitive chemoradiotherapy or definitive RT alone in patients with NSCLC.

Prognostic Impact of Total Lesion Glycolysis (TLG) from Preoperative 18F-FDG PET/CT in Stage II/III Colorectal Adenocarcinoma: Extending the Value of PET/CT for Resectable Disease

We investigated the prognostic role of metabolic parameters from preoperative ¹⁸F-FDG PET/CT in stage II/III colorectal adenocarcinoma. A total of 327 stage II/III colorectal adenocarcinoma patients who underwent curative resection were included. The maximal standard uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were analyzed for optimal cut-offs and their effect on DFS. Differences in DFS rates and hazard ratios for DFS between cut-offs were statistically significant in SUVmax, MTV2.5, MTV3, TLG 2.5, TLG3, and TLG30%. Factors significantly related to DFS in univariate Cox regression were age, sex, stage, preoperative CEA, SUVmax, MTV2.5, MTV3, TLG2.5, TLG3, and TLG30%. Age, sex, preoperative CEA, and TLG2.5 (p = 0.009) sustained statistically significant difference in multivariate analysis. The 1-, 3-, and 5-year DFS rates for TLG2.5 ≤ 448.5 were 98.1%, 79.6%, and 74.8%, significantly higher than 78.4%, 68.5%, and 61.1% of TLG2.5 > 448.5, respectively (p = 0.012). TLG, a parameter indicating both the metabolic activity and metabolic volume, was the strongest predictor independently associated with DFS, among several PET parameters with statistical significance. These results suggest the potential prognostic value of preoperative ¹⁸F-FDG PET/CT in stage II/III resectable colorectal cancer.

Progress and future prospective of FDG-PET/CT imaging combined with optimized procedures in lung cancer: toward precision medicine

With a 5-year overall survival of approximately 20%, lung cancer has always been the number one cancer-specific killer all over the world. As a fusion of positron emission computed tomography (PET) and computed tomography (CT), PET/CT has revolutionized cancer imaging over the past 20 years. In this review, we focused on the optimization of the function of 18F-flurodeoxyglucose (FDG)-PET/CT in diagnosis, prognostic prediction and therapy management of lung cancers by computer programs. FDG-PET/CT has demonstrated a surprising role in development of therapeutic biomarkers, prediction of therapeutic responses and long-term survival, which could be conducive to solving existing dilemmas. Meanwhile, novel tracers and optimized procedures are also developed to control the quality and improve the effect of PET/CT. With the continuous development of some new imaging agents and their clinical applications, application value of PET/CT has broad prospects in this area.

Evaluation of tumor response after stereotactic body radiation therapy for lung cancer: Role of 18F-fluorodeoxyglucose positron emission tomography/computed tomography

BACKGROUND

Early identification of patients who fail to lung stereotactic body radiation therapy (SBRT) is vital as they can benefit from salvage therapy. Main guidelines recommend computed tomography (CT) to assess response and use of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/CT only when a local recurrence is suspected in CT. The pattern of radiation-induced lung injury caused by SBRT is different from changes seen after conventional radiation therapy in terms of extent, time of manifestation, and morphologic characteristics, and knowing this is crucial for proper monitoring of the tumor response. In certain cases, it may be difficult to differentiate response from progression or recurrence on CT and, in addition, some changes in CT take a long time to evolve before they are considered suspicious, making early diagnosis difficult. Metabolic changes often precede morphological changes, so 18F-FDG PET/CT quantitative and qualitative metabolic criteria can be useful in assessing early response and detecting relapses. However, the optimal practice for follow-up remains unclear and there is an active search for imaging markers for recurrent disease, including CT texture analysis, biomarker assays, new PET/CT isotopes, and magnetic resonance imaging.

AIM

The aim of the study was to review the radiological changes that are objectified after pulmonary SBRT and the metabolic changes in 1F-FDG PET/CT, to assess the usefulness of following up patients with 18F-FDG PET/CT.

RELEVANCE FOR PATIENTS

At present, the evaluation of response and diagnosis of relapse after SBRT are difficult and the incorporation of routine 18F-FDG PET/CT may have value in early diagnosis of relapse when the patient may still benefit from rescue treatment.

Can high-risk CT features suggest local recurrence after stereotactic body radiation therapy for lung cancer? A systematic review and meta-analysis

PURPOSE

To perform a systematic review and meta-analysis evaluating usefulness of high-risk CT features (HRFs) on follow-up CT in detecting local recurrence after stereotactic body radiation therapy (SBRT) in lung cancer patients.

METHODS

Pubmed and EMBASE were searched up to January 11th, 2019. We included studies that differentiated local recurrence from post-SBRT changes after SBRT on follow-up CT in lung cancer patients. Methodological quality was assessed using QUADAS-2. The association between HRFs and local recurrence were pooled in the form of odds ratio (OR) using the random effects model. Heterogeneity was examined by the Inconsistency index (I²).

RESULTS

Eight studies were included, consisting of 356 lung cancer patients. The overall prevalence of patients with local recurrence was 18.8 % (67/356). Compared with post-SBRT changes, local recurrence after SBRT more frequently demonstrated air-bronchogram disappearance (OR = 7.15), bulging margin (OR = 24.12), craniocaudal growth (OR = 26.07), enlargement after 12 months (OR = 28.11), enlarging opacity (OR = 7.92), linear margin disappearance (OR = 29.24), and sequential enlargement (OR = 83.23) (p ≤ 0.02). Pleural effusion appearance was not related with local recurrence (p = 0.82). Heterogeneity varied among HRFs (I² = 0-91 %). The quality of the studies was considered moderate.

CONCLUSIONS

Several HRFs on follow-up CT after SBRT were useful in suggesting local recurrence. These HRFs may help raise clinical suspicion of local recurrence, initiate prompt additional test for confirmation and perform subsequent proper personalized salvage treatment.

Impact of positron emission tomography with computed tomography for image-guided radiotherapy

Therapeutic effectiveness in radiotherapy is partly related to correct staging of the disease and then precise therapeutic targeting. Positron emission tomography (PET) allows the stage of many cancers to be determined and therefore is essential before deciding on radiation treatment. The definition of the therapeutic target is essential to obtain correct tumour control and limit side effects. The part of adaptive radiotherapy remains to be defined, but PET by its functional nature makes it possible to define the prognosis of many cancers and to consider radiotherapy adapted to the initial response allowing an increase over the entire metabolic volume, or targeted at a subvolume at risk per dose painting, or with a decrease in the dose in case of good response at interim assessment.

[Prognosis factors after lung stereotactic body radiotherapy for non-small cell lung carcinoma]

Lung cancer is the fourth most common cancer in France with a prevalence of 30,000 new cases per year. Lobectomy surgery with dissection is the gold standard treatment for T1-T2 localized non-small cell lung carcinoma. A segmentectomy may be proposed to operable patients but fragile from a respiratory point of view. For inoperable patients or patients with unsatisfactory pulmonary function tests, local treatment with stereotactic radiotherapy may be proposed to achieve local control rates ranging from 85 to 95% at 3-5 years. Several studies have examined prognostic factors after stereotaxic pulmonary radiotherapy. We conducted a general review of the literature to identify factors affecting local control.

SUVmax Predicts Disease Progression after Stereotactic Ablative Radiotherapy in Stage I Non-small Cell Lung Cancer

Purpose

Fluorodeoxyglucose positron emission tomography–computed tomography (PET-CT) is gaining evidence as a predictive factor in non-small cell lung cancer (NSCLC). Stereotactic ablative radiotherapy (SABR) is the standard treatment in early-stage NSCLC when a patient is unsuitable for surgery. We performed a study to assess the prognostic clinical significance of PET-CT after SABR in early-stage NSCLC.

Materials and Methods

Seventy-six patients with stage I NSCLC treated with SABR were investigated. Total radiation dose ranged from 36 to 63 Gy in three to eight fractions depending on tumor location and size. Respiratory motion control was implemented at simulation and during treatment. PET-CT prior to SABR was performed in 66 patients (86.8%).

Results

Median follow-up time was 32 months (range, 5 to 142 months). Local control rate at 1, 2, and 5 years were 95.9%, 92.8%, and 86.7%, respectively. Overall survival (OS) at 1, 2, and 5 years were 91.0%, 71.3%, and 52.1% respectively. Cause-specific survival at 1, 2, and 5 years were 98.6%, 93.1%, and 84.3% respectively. Tumor size and pre-SABR maximal standardized uptake value (SUVmax) demonstrated statistical significance in the Kaplan-Meier survival analyses with log-rank test. In multivariate analyses pre-SABR SUVmax remained statistically significant in correlation to OS (p=0.024; hazard ratio [HR], 3.2; 95% confidence interval [CI], 1.2 to 8.8) and with marginal significance in regards to regional progression-free survival (p=0.059; HR, 32.5; 95% CI, 2.6 to 402.5).

Conclusion

Pre-SABR SUVmax demonstrated a predictive power in statistical analyses. Tumors with SUVmax above 6 at diagnosis were associated with inferior outcomes.