Apolipoprotein A1 and lipoprotein(a) are protective factors for male papillary thyroid cancer patients. A cross-sectional study of single academic center in China.

Background: Papillary thyroid cancer (PTC) is the most common type of thyroid cancer and the incidence of PTC continued to increase over the past decades. Many studies showed that obesity is an independent risk factor for PTC and obese PTC patients tend to have a relative larger tumor size and higher grade of tumor stage. Obesity is closely related with lipid metabolism, while the correlation between serum lipid and PTC remains unclear. Therefore, this study aimed to investigate the association between serum lipid level and PTC. Methods: We retrospectively analyzed 1018 PTC patients diagnosed and treated in our hospital, all these cases were first diagnosed with PTC and had complete clinical information including ultrasound reports before surgery, serum lipid (CHOL, TG, HDL-c, LDL-c, Apo-A1, Apo-B, Apo-E, Lp (a)) results, surgical records and pathological reports. Results: All these serum lipid biomarkers did not associated with tumor size in the female group. In the male group, on crude analysis, Apo-A1 and Lp (a) showed a marginally significant association with tumor size OR and 95% CI 0.158 (0.021-1.777), p=0.072; 0.997 (0.993-1.000) p=0.082 respectively. After adjusting for age and multifocality, Apo-A1 and Lp (a) showed a significant association with tumor size OR and 95% CI 0.126 (0.016-0.974) p=0.047; 0.996 (0.992-1.000) p=0.046 respectively. This association become more apparent in a young male subgroup, OR and 95% CI 0.051 (0.005-0.497), p=0.009; 0.926 (0.978-1.012), p=0.037 respectively. CHOL, TG, HDL-c, LDL-c, Apo-B, Apo-E did not show significant association with tumor size. As for LNM, neither in the male group nor in the female group were found to be associated with any serum lipid biomarkers. Conclusion: As PTC incidences continues to increase, our study demonstrated that Apo-A1 and Lp (a) are two protective factors for male PTC patients and provided us new clues about PTC and lipid metabolism, which may contribute to further investigation concerning diagnosing and preventing this most common type of thyroid cancer.