Patients with tumours >4.0 cm showed significantly worse outcomes in RFS compared with those with smaller tumours. This relationship was also noted in patients with Stage I disease.

Human 8-oxoguanine DNA glycosylase 1 (hOGG1) has a major role in the repair of 8-hydroxyguanine, a major promutagenic DNA lesion. The genetic polymorphism rs1052133, which leads to substitution of the amino acid at codon 326 from Ser to Cys, shows functional differences, namely a decrease in enzyme activity in hOGG1-Cys326. Although several studies have investigated the association between rs1052133 and lung cancer susceptibility, the effect of this locus on lung cancer according to histology remains unclear. We therefore conducted a case-control study with 515 incident lung cancer cases and 1030 age-and sex-matched controls without cancer, and further conducted a meta-analysis. In overall analysis, the homozygous Cys/Cys genotype showed a significant association with lung cancer compared to Ser allele carrier status (odds ratio (OR)¼1.31, 95% confidence interval (CI)¼1.02-1.69). By histology-based analysis, the Cys/Cys genotype showed a significantly positive association with small-cell carcinoma (OR¼2.40, 95% CI¼1.32-4.49) and marginally significant association with adenocarcinoma (OR¼1.32, 95% CI¼0.98-1.77). A meta-analysis of previous and our present study revealed that this polymorphism is positively associated with adenocarcinoma, although suggestive associations were also found for squamousand small-cell lung cancers. These results indicate that rs1052133 contributes to the risk of adenocarcinoma of lung.

The newly proposed classification for thymic malignancies does not serve as a prognostic prediction model for overall survival but served as a significant imbalance of stage distribution in our cohort. However, it appears to be beneficial, especially in clinical settings and recurrence-free survival analysis.

Our results show the clinical feasibility of our stepwise approach to the differential diagnosis of primary lung cancer and breast cancer relapse presenting as a solitary nodule in patients after mastectomy.