Vienna doctors urge caution when assessing possible associations between liver cancer recurrence and use of DAAs

Doctors in Vienna, Austria, recently reported a group of cases of liver cancer in 19 participants whose hepatitis C virus (HCV) was treated with direct acting antivirals (DAAs). Three of these participants had previously been diagnosed with liver cancer. Nearly all had been infected with HCV for many years and had what the doctors called “advanced liver disease.”

The Austrian doctors cautioned people who read their report to bear in mind the following:

  • As their patients had advanced liver disease, they were already at high risk for liver cancer (and its recurrence in people who previously had this cancer).
  • Since they were already at high risk for liver cancer, the development of such tumours in relation to the timing of DAA therapy could have occurred by “chance.”
  • Although regular ultrasound scans, and in some cases CT or MRI scans, are recommended as part of liver cancer screening, they note: “Even the best imaging methods cannot exclude a small [liver tumour with 100% certainty].”

The doctors concluded that an apparently increased risk for liver cancer in some patients who have been treated with DAAs might be due to the following factor:

  • older age – this represents a surrogate or stand-in indicating prolonged chronic HCV infection. Long-term HCV infection would have allowed more time for scarring of the liver to have occurred and therefore an increased risk for liver cancer.

The Austrian doctors also found it “difficult to develop” a highly robust estimate of the risk for liver cancer in their clinic’s population. However, their interim data suggest that among patients who were cured of HCV with DAAs the subsequent risk for developing liver cancer is about 5%.

They also stated that among 94 other patients in their clinic who were cured of HCV with a combination of interferon and ribavirin, 10 developed liver cancer after nearly eight years of monitoring. Thus, about 11% of these 94 interferon-treated patients developed liver cancer. This is another piece of evidence underscoring that interferon-based therapy does not provide 100% protection from the risk of developing liver cancer.

The Austrian doctors stated that their findings have several implications, including the following:

  • Patients with cirrhosis should undergo regular screening for liver cancer even after they have been cured of HCV.
  • Treating HCV-infected patients who do not have cirrhosis as early as possible may help to reduce their future risk for developing liver cancer.

—Sean R. Hosein

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