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

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.