Using positron emission tomography - computed tomography imaging to distinguish of metastatic disease from second primary lung tumours in patients with non-small cell lung cancer

Background: In NSCLC patients with multiple lesions, the differentiation between metastases and second primary tumours has significant therapeutic and prognostic implications. The aim of this retrospective study was to investigate the potential of 18F-FDG PET to discriminate metastatic disease from second primary lung tumours.Methods: Of 318 NSCLC patients between November 2015 and October 2018 at Bach Mai hospital, patients with a synchronous second primary lung cancer were selected. Patients with metastatic disease involving the lungs served as the control group. Maximum standardized uptake values (SUVs) measured with 18F-FDG PET were determined for two tumours in each patient. The SUVmax was determined and compared between the second primary group and metastatic disease group. Receiver-operating characteristic (ROC) curve analysis was performed to determine the sensitivity and specificity of the SUVmax for an optimal cut-off value.Results: A total of 81 NSCLC patients (44 metastatic disease, 37 second primary cancer) were included for analysis. The SUVmax was significantly higher in patients with second primary cancer than in those with metastatic disease (7.53±4.33 vs 4.35±2.58, respectively, p<0.001). The area under the ROC curve was 0.81 and the odds ratio for the optimal cut-off was 7.52.Conclusions: SUVmax from 18F-FDG PET images can be helpful in differentiating metastatic disease from second primary tumours in patients with synchronous pulmonary lesions. Further studies are warranted to confirm the consistency of these results.

The Role of Surgery for Asymptomatic Primary Tumors in Unresectable Stage IV Colorectal Cancer

There are still debates regarding the appropriate primary treatment policy for asymptomatic primary colorectal lesions in cases of unresectable metastatic colorectal cancer. Even though there are patients with asymptomatic primary tumors when starting chemotherapy, those patients may still undergo surgery due to complications related to primary tumors in the middle of chemotherapy; therefore, controversy exists regarding surgical resection of primary colorectal lesions in cases where symptoms are absent when making a diagnosis. Thus, based on the published literature, we discuss opinions that prefer first-line surgery for primary tumors as well as opinions favoring first-line chemotherapy for treating unresectable synchronous metastatic colorectal cancer. Although the upfront chemotherapy including targeted agents is suggested as an effective treatment in recent years, the first line surgery has been a preferred treatment for decades. The first line surgery is beneficial to prolong the survival duration given the retrospective analysis of randomized trial data. So far, no prospective comparison study has only focused on the first-line treatment modality; thus, future clinical studies focusing on the survival duration and the quality of life should be performed as soon as possible. Furthermore, at this point, multidisciplinary team approaches would be helpful in finding the appropriate therapy. Regardless of symptoms, the performance status and the tumor burden should be taken into consideration as well. In case of surgical resection, minimally invasive surgery, such as laparoscopic surgery, is recommended.