Research on the value of the T cell spot test for tuberculosis for the diagnosis of lung cancer combined with pulmonary tuberculosis

Abstract

Background: This study was conducted to investigate the value of the T cell spot test for tuberculosis (T-SPOT.TB) for the diagnosis of patients with lung cancer combined with pulmonary tuberculosis (LCTB). Methods: Thirty-six patients diagnosed with LCTB who received treatment at Shandong Provincial Chest Hospital from September 2014 to 2017 were randomly chosen and enrolled as an observation group; 63 patients diagnosed with LC alone in the same period were included as the control. The T-SPOT.TB results of the two groups were compared. Results: The positive rate of T-SPOT.TB in 36 patients with LCTB was 88.9% (32/36), and in 63 patients with LC was 23.8% (15/63). The median ESAT-6 result in the LCTB group was 22 SFCs/2.5 × 10 5 peripheral blood monocytes (PBMC) (interquartile range [IQR] 8–53), which was higher than in the LC group with a median of 1 spot-forming cell (SFC)/2.5 × 10 5 PBMC (IQR 0–5). The median CFP10 result in the LCTB group was 18 SFCs/2.5 × 10 5 PBMC (IQR 7–30), which was significantly higher than in the LC group with a median of 0 SFC/2.5 × 10 5 PBMC (IQR 0–4). The receiver operating characteristic curve of the two groups showed sensitivity of 88.9% and specificity of 84.4% when the positive value of T-SPOT.TB was 11 SFCs/2.5 × 10 5 PBMC. Conclusions: T-SPOT.TB has comparatively high value for diagnosing LCTB. The referential cutoff value is 11 SFCs/2.5 × 10 5 PBMC, which warrants clinical application.