Plasma levels of methylated septin 9 are capable of detecting hepatocellular carcinoma and hepatic cirrhosis.

Hepatocellular carcinoma (HCC) was the third most common cause of cancer‑associated mortality in China in 2015. Early detection of HCC and hepatic cirrhosis (HC) can serve a crucial role in the prevention and therapeutic intervention of these diseases. Current early detection methods rely on less sensitive imaging modalities compared with the pathological examination. In the present study, a total of 64 patients with HCC, 44 patients with HC and 298 individuals with no evidence of disease (NED) were recruited, and the ability of methylated septin 9 (mSEPT9) in diagnosing HCC and HC was investigated. The overall detection sensitivity of mSEPT9 for HCC and HC was 76.7 and 34.1%, respectively, with a 95.9% specificity (HCC vs. NED). The sensitivity of mSEPT9 for HCC was significantly higher than that of α‑fetoprotein (AFP; χ2 test; 56.7%; P<0.05). The areas under the curve from the receiver operating characteristic curves of mSEPT9 for detection of HCC vs. NED, HC vs. NED and HCC vs. HC were 0.85, 0.77 and 0.66, respectively, while those of AFP for the same groups were 0.80, 0.55 and 0.77, respectively. Although both markers exhibited stage‑dependent sensitivity in HCC, mSEPT9 was demonstrated to be more sensitive than AFP. The net reclassification index of mSPET9 for HCC detection was 0.212 compared with AFP, suggesting an improved diagnostic performance of mSEPT9 compared with AFP. In addition, Kaplan‑Meier survival analysis revealed that mSEPT9 is able to predict the long‑term survival of patients with HCC. Further analysis suggested that patients >50 years of age exhibited higher sensitivity compared with those <50 years old in mSEPT9, but not in AFP. No significant difference in sensitivity was observed between compensated and decompensated patients with HC, and in patients with HC with a history of hepatitis B or C virus infection. No difference was observed between male and female subjects in the HC and HCC groups for mSEPT9 and AFP. In conclusion, mSEPT9 may detect HCC with an overall improved sensitivity compared with AFP and may help in predicting the long‑term survival of patients with HCC. The present clinical study was retrospectively registered to the Chinese Clinical Trial Registry on April 4, 2020 (http://www.chictr.org.cn/enIndex.aspx; registration no. ChiCTR2000031547).