A study of the entire population of people treated for hepatitis C in British Columbia province between 1990 and 2013, Canada found that the risk of liver cancer was reduced by 80% in people cured of hepatitis C compared to those who were not cured. This study did not look at the relationship between exposure to DAAs and liver cancer risk.

The study identified 8147 people treated with interferon-based regimens, 57% of whom were cured. Treated individuals were followed for a median of 5.6 years.

Liver cancer incidence was highest among those with cirrhosis who did not achieve a sustained virologic response (21 cases per 1000 patient-years of follow up). In comparison liver cancer incidence was 6.4 per 1000 patient-years in those with cirrhosis who achieved SVR, 7.2 in those who without cirrhosis who did not achieve SVR12 and 1.1 per 1000 patient-years in those without cirrhosis who achieved SVR12.

In a multivariable analysis liver cancer was associated with cirrhosis, age over 50 years, genotype 3 infection versus genotype 1, alcohol consumption and being male in those who were not cured. In those who were cured of hepatitis C, only cirrhosis, age over 50 and being male were associated with an increased risk of liver cancer.

The British Columbia researchers concluded that although curing hepatitis C infection greatly reduces the risk of developing liver cancer, it does not eliminate the risk entirely. Older people and those with cirrhosis are at higher risk than others, underlining the importance of early diagnosis and treatment.

The study also found that risk was related to when people where treated. For example, when patients were treated at a more advanced stage when they had cirrhosis, the impact of successful treatment was lower than if they were treated before the developed of cirrhosis, says Zafar Janjua.

This has significant implications because, although effective treatments are available for hepatitis C, most people are currently being treated at more advanced-stage disease. Many insurance plans in both the U.S. and Canada are not covering treatment for hepatitis C until a later stage, says Zafar Janjua.

Janjua NZ et al. The impact of sustained virological response to HCV infection on long term risk of hepatocellular carcinoma: the BC Hepatitis Testers Cohort. Hepatology Special Issue, The 67th Meeting of the American Association for the Study of Liver Diseases: The Liver Meeting, abstract 175.

Sources: http://www.aidsmap.com/Liver-cancer-risk-reduced-after-hepatitis-C-treatment-but-vigilance-needed-for-aggressive-cancers-in-months-after-treatment/page/3099046/ and http://www.onclive.com/conference-coverage/aasld-2016/dr-naveed-zafar-janjua-on-impact-of-hepatitis-c-treatment-timing-on-hcc-risk#sthash.FyvUiMKJ.dpuf