Is Primary Tumor Metabolic Activity a Risk Factor for Occult Lymph Node Metastasis in T1-2N0M0 Non-small Cell Lung Cancer Patients?

Objective: In our study we aimed to evaluate the potential risk factors for occult lymph node metastasis with PET-CT in patients with clinically stage I NSCLC. Methods:Hospital records of 26 patients who were clinically diagnosed with stage 1 NSNLC in our unit with PET-CT, operated and underwent systemic lymph node dissection were retrospectively analysed. Demographic features, time to surgery and histologic type, differentiation grade, localisation, diameter at PET-CT and SUVmax values of the tumor were recorded. The patients were divided into three groups according to the diameter and the median SUVmax value of the primary mass at PET/CT: Group 1 (low risk group) T <= 3 cm and SUVmax< 11.6, group 2 (middle risk group) 3cm<T <= 5 cm and SUVmax<11.6, group 3 (high risk group) T <= 7 cm or SUVmax 11.6.Possible risk factors for occult lymph node metastasis were evaluated. Results:22 of the patients (84.6%) were male and 4 (15.4%) were female. The mean age was 64.5 +/- 9.8 (min: 42 max: 83). All of the patients were diagnosed with T1-2N0M0 stage 1 with PET/CT preoperatively. 20 of the patients (76.9) had lobectomy, 4 (15.4%) had pneumonectomy and 2 (7.7%) had segmentectomy. All of the patients underwent systemic lymph node dissection during the surgery. Among twenty-six patients, 4 (15.4%) patients had surgery N1 lymph node positivity. Tumor histological type of 4 patients who had surgically N1 lymph node positivity were adenocarcinoma. Occult lymph node metastasis ratio in groups 1,2 and 3 were 2/9 (22.2%), 1/4 (25.0%) and 1/13 (7.7%) respectively. There were no statistically significant difference between the groups (Table 3). Conclusion: In patients with T1-2N0M0 disease, the size and the SUVmax of the primary tumor in the preoperative PET/CT cann't be used for the prediction of occult node metastasis.