The role of positron emission tomography in the diagnosis, staging and response assessment of non-small cell lung cancer

Defining Synchronous Oligometastatic Non-Small Cell Lung Cancer: A Systematic Review

INTRODUCTION

Synchronous oligometastatic (sOM) disease is an oncological concept characterized by a limited cancer burden. Patients with oligometastasis could potentially benefit from local radical treatments. Despite the fact that the sOM condition is well recognized, a universal definition, including a specific definition for NSCLC, is not yet available. The aim of this systematic review was to summarize the definitions of and staging requirements for use of the term synchronous oligometastatic in the context of NSCLC.

METHODS

The key issue was formulated in one research question according to the population, intervention, comparator, and outcomes strategy. The question was introduced in MEDLINE (OvidSP). All articles dealing with sOM NSCLC and providing a definition of synchronous oligometastasis in NSCLC were selected and analyzed.

RESULTS

A total of 21 eligible articles focusing on sOM NSCLC were retrieved and analyzed. In 17 studies (81%), patients had to be staged with magnetic resonance imaging or computed tomography of the brain, thoracic and abdominal computed tomography, and positron emission tomography. The total number of metastases allowed in the definitions ranged from one to eight, but in 38.1% of studies the maximum number was 5. Most of the publications did not define the number of involved organs or the maximum number of metastases per organ. For mediastinal lymph node involvement, only five articles (27.8%) counted this as a metastatic site.

CONCLUSIONS

No uniform definition of sOM NSCLC could be retrieved by this systematic review. However, extended staging was mandated in most of the studies. An accepted oncological definition of synchronous oligometastasis is essential for patient selection to define prospective clinical trials.

Correlation study on 18F-FDG PET/CT metabolic characteristics of primary lesion with clinical stage in lung cancer

BACKGROUND

¹⁸F-FDG PET/CT metabolic characteristics provide the crucial biologic and molecular information for tumors. To explore the relationships between ¹⁸F-FDG PET/CT derived parameters such as maximum standardized uptake value (SUV<inf>max</inf>), metabolic tumor volume (MTV), total lesion glycolysis (TLG) of primary tumor and clinical stage in different histopathologic subtypes of lung cancer.

METHODS

A total of 97 newly diagnosed lung cancer patients (69 males, 28 females; average age 65.1 years) with pathologically proven were retrospectively analyzed, who had undergone ¹⁸F-FDG PET/CT scan before treatment from September 2016 to November 2017. SUV<inf>max</inf>, MTV and TLG of primary tumor were measured. Clinical stage was mainly determined by ¹⁸F-FDG PET/CT, in conjunction with conventional imaging and endoscopic biopsy. Mann-Whitney U test, χ² test, Spearman correlation test and ROC curve analysis were used for statistical analysis.

RESULTS

There were 53 adenocarcinomas (AC), 28 squamous carcinomas (SCC), 13 small cell carcinomas (SCLC), one adenosquamous carcinoma, one mucoepidermoid carcinoma, and one sarcomatoid carcinoma in 97 patients. Both AC and SCLC revealed more cases in stage IV than in stage I-III (P<0.01). There was no significant difference in four stages of SCC (P>0.05). Metabolic parameters of SCC were higher than AC including SUV<inf>max</inf>, MTV and TLG (P<0.01). SCLC showed a higher value than AC in TLG (P<0.05). No significant differences were found between AC and SCLC in SUV<inf>max</inf> and MTV, also between SCC and SCLC in SUV<inf>max</inf>, MTV and TLG (P>0.05). MTV and TLG except SUV<inf>max</inf> were positively correlated with stage in AC (P≤0.001). Only MTV showed a positive correlation with stage in SCC (P<0.05). Whereas there were no definitive relationships between metabolic parameters and stage in SCLC (P>0.05). AC with a higher MTV (MTV≥5.965 cm³) indicated a significantly higher rate of distant metastasis than those with a lower MTV (77.5% (31/40) vs. 30.8% (4/13), χ²=9.553, P<0.01), as well as AC with a higher TLG (TLG≥46.922) than those with a lower TLG (88.5% (23/26) vs. 44.4% (12/27), χ²=11.422, P<0.01).

CONCLUSIONS

Histopathologic subtypes have a significant influence on the relationships between MTV/TLG not SUV<inf>max</inf> of primary foci and stage in lung cancer. Primary MTV/TLG is related to clinical stage closely in AC, and a higher MTV/TLG results in a higher risk of distant metastasis.

Usefulness of both PET/CT with F18-FDG and whole-body diffusion-weighted imaging in cancer screening: a preliminary report

OBJECTIVE

Positron emission tomography/computed tomography (PET/CT) with fluorodeoxyglucose (F18-FDG) is useful for the detection of malignant lesions, including metastatic lesions, and this technique is widely used in cancer screening. However, this approach may occasionally yield false-positive and false-negative findings. At our PET center, to increase the accuracy of PET/CT, we use PET/CT and whole-body diffusion-weighted imaging (WB-DWI) together. This study aimed to assess the usefulness of this combination.

METHODS

We examined 29 subjects with confirmed diagnosis. All of them had undergone PET/CT and WB-DWI on the same day. Twenty-seven of them also underwent ultrasonography, blood testing, and upper gastrointestinal series on the same day and two fecal occult blood tests on another day. WB-DWI was performed on a 1.5-T MRI unit with a b value of 0 and 800 or 1000 s/mm². For all 29 cases, PET/CT and WB-DWI were classified to be positive or negative, and the diagnostic ability was calculated for each modality.

RESULTS

Among the 29 subjects, 17 had malignant tumors and 12 had benign tumors or no abnormalities. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PET/CT were 65%, 25%, 55%, 33%, and 48%, respectively; while the corresponding values for WB-DWI were 59%, 100%, 100%, 63%, and 76%, respectively. By considering the result to be negative when PET/CT findings were positive but WB-DWI findings were negative, specificity increased from 25 to 100%, and accuracy increased from 48 to 76%. On the other hand, by considering the result to be positive when the findings of either PET/CT or WB-DWI were positive, sensitivity increased from 65 to 76%, and accuracy increased from 48 to 55%.

CONCLUSIONS

Our results suggest that using both PET/CT and WB-DWI together can increase accuracy in cancer screening. However, this approach was not able to detect malignant lesions in some cases, indicating that there were limitations with imaging certain organs. Therefore, it is important to further understand the features of PET/CT and WB-DWI and use them appropriately for each organ. Additionally, given that the study sample was relatively small, further research is needed to validate these findings.