We retrospectively reviewed 54 patients with histologically or cytologically proven SCLC who had undergone pre-treatment 18F-FDG-PET/CT scanning from September 2007 to November 2011 in the Dicle University, School of Medicine, Department of Medical Oncology. They met the following inclusion criteria; (1) 18 or more years old; (2) a histologic or cytologic diagnosis of SCLC; (3) no previous chemotherapy or radiotherapy; (4) there was sufficient clinical data recorded in medical records; (5) they had to have a measurable disease, as defined by Response Evaluation Criteria in Solid Tumours (RECIST).

Patients were identified as having DM on the basis of elevated fasting glucose level (>126mg/dL), and a history of DM or medication use, such as insulin or oral hypoglycemic agents.

Patients with LD underwent concurrent chemoradiotherapy, which consisted of chemotherapy and thoracic radiotherapy. Both LD and ED patients were receiving first-line EP chemotherapy. The EP regimen consisted of 100mg/m2 etoposide on days 1 and 30mg/m2 cisplatin on days 1–3, every 3 weeks.

All had SCLC. Patients who had received prior treatment were excluded.

FDG-PET was carried out in all cases within 6 weeks before SRBT. All patients fasted for at least 4h before the 18F-FDG-PET/CT examination though oral hydration with glucose-free water was given. When peripheral blood glucose level before administration of 18F-FDG was <150mg/dL, patients received an intravenous injection of 3.70–4.44MBq/kg of FDG. Whole-body FDG-PET was scanned using the same scanner, Biograph 6 PET/CT scanner (CTI/Siemens, Knoxville, TN). The axes of both systems were mechanically aligned so that the patient could be moved from the CT scanner to the PET scanner gantry. The resulting of PET and CT scans co-registered on the same hardware. Then, 1 hour after the injection, CT and PET scans were performed. Images from the level of the middle skull to the proximal thigh were obtained. CT scan was implemented with the following settings: 110kV; 80mA; tube rotation time, 0.8s/rotation per pitch, and section thickness, 3.0mm (whole body CT had 307 or 356 slices). The PET and CT scans were obtained during normal tidal breathing. The PET scans were done immediately after the CT scans. The PET/CT scans were obtained in 3D mode at 3min per bed position.

As a semi-quantitative analysis, the maximum standardized uptake value (SUVmax) was achieved by placing region of interest (ROIs) over the lesions that had been determined as suspicious on visual assessment. SUVmax of the pulmonary tumor was calculated in all cases using a 3D acquisition and the following formula:

The maximum standardized uptake value (SUVmax) was represented by the counts per second of the voxel showing the maximum radioactivity in the volume of interest encompassing the tumor divided by the volume of the voxel (mL).

PET data were iteratively reconstructed using an ordered subset expectation maximization algorithm and segmented attenuation correction (2 iterations, 8 subsets) and the CT data. Co-registered scans were displayed using dedicated software (e-soft-PET; Siemens Medical Solutions).

Two experienced nuclear medicine physicians, who were unaware of the clinical results, viewed and quantitatively analyzed the PET images.

Eleven potential prognostic variables were chosen on the basis of previously published clinical trials. The variables were divided into categories: age (<65 or ≥65), gender (male or female), performance status (PS) (0–1, 2–3), stage (LD or ED), weight loss ≥5% with previous 3 months (present or absent), diabetes mellitus (present or absent), smoking history (present or absent), SUVmax values (<13.0 or ≥13.0), laboratory parameters [(albumin, LDH, blood sugar) (

The values of SUVmax were detected between 5 and 20 in prior studies with log-rank probability values to determine a prognostic cutoff point for SUVmax. Because no statistically significant value was found, SUVmax was dichotomized at its median of 12.9 in present study.

All of the analyses were performed using the SPSS statistical software program package (SPSS version 11.5 for windows). The differences in the clinical characteristics between the two groups were analyzed by chi-square test and student t test. Overall survival (OS) was calculated from the start of the first cycle of chemotherapy to the date of death from any cause or the date of the last follow-up. Overall survival was estimated using the Kaplan–Meier method. The Cox proportional hazards regression model was used to determine statistical significant variables related to survival. Differences were assumed to be significant when p value was less than 0.05.

Between September 2007 and November 2011, 54 patients with SCLC were enrolled in this study. The median age of patients was 57 years (range 28–80) with 50 (92.6%) males and 4 (7.4%) females. The number of patients with a PS score 0–1 was 34 (63.0%). Thirty patients (55.6%) were diagnosed as having extended disease and 24 patients (44.4%) had limited disease. The estimated median OS with LD was 17.3 months (95% CI, 8.9–25.7 months). Median OS of the treated ED patients was 8.4 months (95% CI, 7.1–9.8 months). The patients’ baseline characteristics are listed in Table 1.

The results of univariate analysis are summarized in Table 2. Among the eleven variables of univariate analysis, three variables were identified as having prognostic significance: Performance status (p<0.001), stage (p=0.02) and diabetes mellitus (p=0.05). Multivariate analysis included the three prognostic significance factors in univariate analysis. The results of multivariate analysis are shown in Table 3. Multivariate analysis by Cox proportional hazard model showed that performance status and stage were considered independent prognostic factors for survival (p<0.001 and p=0.002 respectively) (Figs. 1 and 2).

Figure 1.

Survival of patients according to performance status.

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Figure 2.

Survival of patients according to stage.

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The authors declare that no experiments were performed on humans or animals for this study.

The authors declare that they have followed the protocols of their work center on the publication of patient data and that all the patients included in the study received sufficient information and gave their written informed consent to participate in the study.

The authors have obtained the written informed consent of the patients or subjects mentioned in the article. The corresponding author is in possession of this document.

The authors have no conflicts of interest to declare.