Lung cancer is one of the principle causes of cancer-related deaths worldwide, second only to prostate cancer in men and breast cancer in women. Platinum-based chemotherapy is the standard treatment for advanced non-small lung cancer (NSCLC).
Over the last few decades many approaches to assess treatment response have been proposed passing from morphological to metabolic images. It is possible to follow the metabolic changes by 18F-FDG PET imaging as reported in several studies. The purpose of this study was the evaluation of platinum-based therapy response in NSCLC.
This study considered 17 patients recruited from October 2011 to June 2013. Patients underwent a 18F-FDG PET/CT before treatment and 28±6 days after the initialization of chemo-treatment.
A morphological diagnostic CT scan was performed before and between day 49 and 88 after start treatment. The data were analyzed according to EORTC, PERCIST and RECIST classifications. The new approaches to evaluate the treatment response introduce MTV (Metabolic Tumor Volume), that indicates the volume of metabolically active tumors, and TLG (Total Lesion Glycolysis), calculated as the product of the SUV mean and MTV.
Patients were grouped into responders (complete response –CR- and partial response –PR-) and non-responders (stable disease –SD- and progressive disease –PD-). In literature, there are no cut-off points for therapy evaluation based on TLG or MTV. To obtain suitable cut-off points, the receiver operating characteristic curves (ROC) were used.
According to EORTC 5 patients showed 1 PR, 10 SD, and 2 PD; according to PERCIST 4 PR, 11 SD, 2 PD; according to RECIST 1 CR, 4 PR, 4 SD, and 8 PD. For RECIST responder patients median overall survival (OS) was 595 days whereas for non-responder patients median OS was 238 days. For EORTC and PERCIST, OS curves were not statistically significant.
The ROC analysis indicated a cutoff point of -36% for TLG, and -8% for MTV. TLG showed a median OS of 492 days for the 5 responders and 238 days for the 12 non-responders. MTV showed a median of 423 days for the 9 responders versus 188 days for the 8 non-responders.
In patients with NSCLC, 18F-FDG PET/CT is a good staging tool because of its ability to define the primary tumor as well as local and distant metastases.
In the present study, we investigated the metabolic changes assessed by PET, in NSCLC patients treated with platinum-based therapy, using EORTC, PERCIST, MTV and TLG. Data confirmed that TLG proved a strong early prognostic indicator in patients with NSCLC and could avoid the unnecessary administration of non-curative and toxic drugs.