Enhancing the precision of auxiliary diagnosis for lung cancer through use of SHOX2 and RASSF1A methylation status in lung biopsy and lymph node biopsy specimens.

Background: Exfoliated cells in biopsy fluid are commonly utilized for cytological testing to complement histological examination. Nevertheless, the sensitivity of cytological testing is relatively low. Therefore, there is an urgent need to identify more sensitive biomarkers that can substitute for cytology and improve the overall diagnostic accuracy of lung cancer biopsies. The study aims to find biomarkers with greater sensitivity to replace cytology and enhance the overall diagnostic accuracy of lung cancer biopsies by evaluating the complementary roles of cytology and methylation in relation to histology.

Methods: A cohort of 173 patients, including 127 individuals diagnosed with lung cancer and 46 individuals with benign lesions, was successively recruited from Shanghai Chest Hospital. These patients underwent cell smear, ThinPrep cytologic test (TCT), methylation analysis, and histological examination to assess the complementary roles of cytology and methylation in relation to histology could be evaluated.

Results: The cutoff values of SHOX2 and RASSF1A, as determined by the receiver operating characteristic (ROC) curve and scatter plot, were 9 and 12, respectively. The combination of SHOX2 and RASSF1A (LungMe) yielded areas under the curve (AUCs) of 0.967 and 0.999 in lung biopsy and lymph node biopsy liquids, respectively. The sensitivity and specificity of LungMe were 95.3% (121/127) and 97.8% (45/46), respectively. The combination of cytology and histology in the diagnosis of lung cancer did not lead to an increase in diagnostic sensitivity or negative predictive value (NPV), while the combination of LungMe methylation and histology achieved a diagnostic sensitivity and NPV of 100%. The sensitivity of cytology was influenced by the biopsy method, but methylation effectively supplemented cytology in the diagnosis of lung cancer, with a combined diagnostic efficiency of 87.5% to 100%. Furthermore, positive methylation was identified in 87.5% of patients with negative cytology results from lung biopsy and in 100% of patients with negative cytology results in lymph node biopsy. Among samples tested as histologically negative, five cases were observed in which the methylation tests were positive. Among them, four cases were confirmed to be malignant after a second biopsy, surgery, or clinical follow-up, with one case determination pending further evaluation.

Conclusions: The findings suggest that LungMe methylation could replace cytology as an adjunctive diagnostic tool for histology. Moreover, a positive methylation test result could indicate a potential malignancy, necessitating further confirmation by the hospital and thereby reducing the likelihood of missed diagnoses.