PET standardized uptake values of primary lung cancer for comparison with tumor volume doubling times

Negative-predictive value of SUVmax for Ascertaining the efficacy of osimertinib in EGFR mutation-positive non-small cell lung cancer

BACKGROUND

Fluorine-18 2-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) is routinely used to stage non-small cell lung cancer (NSCLC). However, whether 18F-FDG accumulation in primary tumors affects the efficacy of osimertinib in patients with epidermal growth factor receptor (EGFR) mutation-positive NSCLC remains unclear.

METHODS

We retrospectively investigated 74 patients with advanced or postoperative recurrent EGFR mutation-positive NSCLC who underwent 18F-FDG PET/CT and were treated with osimertinib as first-line therapy between September 2018 and March 2023 at Kumamoto University Hospital. The maximum standardized uptake value (SUVmax) of each primary tumor was measured, and the patients were divided into two groups according to the median SUVmax. The effects of SUVmax on progression-free survival (PFS) and overall survival (OS) were assessed using a multivariate Cox proportional hazards model.

RESULTS

The median SUVmax was 8.2 (interquartile range: 5.5-11.4). The median PFS in the high SUVmax group (≥8.2) was significantly shorter than that in the low SUVmax group (<8.2). The respective median PFSs were 11.2 months (95% confidence interval [CI]: 3.1-19.3 months) vs. 22.9 months (95% CI: 12.4-33.4 months) (P = 0.015), although the OS values did not differ significantly. Multivariate analysis showed that a high SUVmax was an independent negative predictive factor for PFS in patients treated with osimertinib (hazard ratio, 2.25; 95% CI: 1.15-4.39, P = 0.017).

CONCLUSIONS

High primary-lesion SUVmax in patients with EGFR mutation-positive NSCLC correlated with shorter PFS with first-line osimertinib therapy, suggesting that SUVmax is a useful predictive marker for the antitumor efficacy of osimertinib.

Performance of Intraoperative Contrast-Enhanced Ultrasound (Io-CEUS) in the Diagnosis of Primary Lung Cancer

BACKGROUND

Suspicious tumors of the lung require specific staging, intraoperative detection, and histological confirmation. We performed an intrathoracic, intraoperative contrast-enhanced ultrasound (Io-CEUS) for characterization of lung cancer.

METHODS

Retrospective analysis of prospectively collected data on the application of Io-CEUS in thoracic surgery for patients with operable lung cancer. Analysis of the preoperative chest CT scan and FDG-PET/CT findings regarding criteria of malignancy. Immediately before lung resection, the intrathoracic Io-CEUS was performed with a contrast-enabled T-probe (6-9 MHz-L3-9i-D) on a high-performance ultrasound machine (Loqic E9, GE). In addition to intraoperative B-mode, color-coded Doppler sonography (CCDS), or power Doppler (macrovascularization) of the lung tumor, contrast enhancement (Io-CEUS) was used after venous application of 2.4-5 mL sulfur hexafluoride (SonoVue, Bracco, Italy) for dynamic recording of microvascularization. The primary endpoint was the characterization of operable lung cancer with Io-CEUS. Secondly, the results of Io-CEUS were compared with the preoperative staging.

RESULTS

The study included 18 patients with operable lung cancer, who received Io-CEUS during minimally invasive thoracic surgery immediately prior to lung resection. In the chest CT scan, the mean size of the lung tumors was 2.54 cm (extension of 0.7-4.5 cm). The mean SUV in the FDG-PET/CT was 7.6 (1.2-16.9). All lung cancers were detected using B-mode and power Doppler confirmed macrovascularization (100%) of the tumors. In addition, Io-CEUS showed an early wash-in with marginal and mostly simultaneous central contrast enhancement.

CONCLUSIONS

The intrathoracic application of Io-CEUS demonstrated a peripheral and simultaneous central contrast enhancement in the early phase, which seems to be characteristic of lung cancer. In comparison to preoperative imaging, Io-CEUS was on par with the detection of malignancy and offers an additional tool for the intraoperative assessment of lung cancer before resection.

Comparison of lung cancer occurring in fibrotic versus non-fibrotic lung on chest CT

PURPOSE

Evaluate the behavior of lung nodules occurring in areas of pulmonary fibrosis and compare them to pulmonary nodules occurring in the non-fibrotic lung parenchyma.

METHODS

This retrospective review of chest CT scans and electronic medical records received expedited IRB approval and a waiver of informed consent. 4500 consecutive patients with a chest CT scan report containing the word fibrosis or a specific type of fibrosis were identified using the system M*Model Catalyst (Maplewood, Minnesota, U.S.). The largest nodule was measured in the longest dimension and re-evaluated, in the same way, on the follow-up exam if multiple time points were available. The nodule doubling time was calculated. If the patient developed cancer, the histologic diagnosis was documented.

RESULTS

Six hundred and nine patients were found to have at least one pulmonary nodule on either the first or the second CT scan. 274 of the largest pulmonary nodules were in the fibrotic tissue and 335 were in the non-fibrotic lung parenchyma. Pathology proven cancer was more common in nodules occurring in areas of pulmonary fibrosis compared to nodules occurring in areas of non-fibrotic lung (34% vs 15%, p < 0.01). Adenocarcinoma was the most common cell type in both groups but more frequent in cancers occurring in non-fibrotic tissue. In the non-fibrotic lung, 1 of 126 (0.8%) of nodules measuring 1 to 6 mm were cancer. In contrast, 5 of 49 (10.2%) of nodules in fibrosis measuring 1 to 6 mm represented biopsy-proven cancer (p < 0.01). The doubling time for squamous cell cancer was shorter in the fibrotic lung compared to non-fibrotic lung, however, the difference was not statistically significant (p = 0.24). 15 incident lung nodules on second CT obtained ≤ 18 months after first CT scan was found in fibrotic lung and eight (53%) were diagnosed as cancer.

CONCLUSIONS

Nodules occurring in fibrotic lung tissue are more likely to be cancer than nodules in the nonfibrotic lung. Incident pulmonary nodules in pulmonary fibrosis have a high likelihood of being cancer.

Discrepancy Between Radiological and Pathological Tumor Size in Early-Stage Non-Small Cell Lung Cancer: A Multicenter Study

Discrepancies between radiological whole tumor size (RTS) and pathological whole tumor size (PTS) are sometimes observed. Unexpected pathological upsize may lead to insufficient margins during procedures like sub lobar resections. Therefore, this study aimed to investigate the current status of these discrepancies and identify factors resulting in pathological upsize in patients with early-stage non-small cell lung cancer (NSCLC). Data from a multicenter database of 3092 patients with clinical stage 0-IA NSCLC who underwent pulmonary resection were retrospectively analyzed. Differences between the RTS and PTS were evaluated using Pearson's correlation analysis and Bland-Altman plots. Unexpected pathological upsize was defined as an upsize of ≥1 cm when compared to the RTS, and the predictive factors of this upsize were identified based on multivariable analyses. The RTS and PTS showed a positive linear relationship (r = 0.659), and the RTS slightly overestimated the PTS. The Bland-Altman plot showed 131 of 3092 (5.2%) cases were over the upper 95% limits of agreement. In multivariable analyses, a maximum standardized uptake value (SUVmax) of the primary tumor on 18-fluoro-2-deoxyglucose positron emission tomography/computed tomography (odds ratio [OR], 1.070; 95% confidence interval [CI], 1.035-1.107; P < 0.001) and the adenocarcinoma histology (OR, 1.899; 95% CI, 1.071-3.369; P =0.049) were independent predictors of unexpected pathological upsize. More of the adenocarcinomas with pathological upsize were moderately or poorly differentiated, when compared to those without. The RTS tends to overestimate the PTS; however, care needs to be taken regarding unexpected pathological upsize, especially in adenocarcinomas with a high SUVmax.