As Greek mythology tells us, the titan Prometheus was punished by the gods for giving fire to man. His sentence? Eternal torture. Each day, an eagle would eat his liver, which would grow back overnight, ready to be devoured by the eagle again the next day.
The liver’s ability to regenerate presumably evolved to protect it from damage from food toxins. However, chronic cycles of liver damage and regeneration can lead to aberrant replication and eventually the development of liver cancer.
October is Liver Cancer Awareness Month. Here’s a look at the latest statistics and trends.
How common is liver cancer?
While the incidence rates of most cancers are decreasing, the number of new liver cancer cases is increasing. In fact, incidence rates of liver cancer have almost doubled since 1992. It is estimated that there will be over 42,000 new cases of liver cancer in the United States this year, accounting for roughly 2 percent of all new cancer cases.
At least 80 percent of liver cancer cases are caused by chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infection. These viruses are transmitted though bodily fluids, and chronic infection often leads to liver inflammation, increasing the risk of liver cancer.
Another major risk factor is cirrhosis, a disease in which healthy liver tissue is replaced by scar tissue. Cirrhosis may be caused by heavy alcohol use, HCV infection, non-alcoholic fatty liver disease, and/or autoimmune diseases that affect the liver.
Race may also influence risk. Asian Americans, Pacific Islanders, Hispanics, and American Indians have the greatest incidence rates of liver cancer in the United States.
Additional risk factors include tobacco use, obesity, and Type 2 diabetes.
What is causing the increasing rates of liver cancer?
One explanation for the rising incidence of liver cancer may be the increasing rates of obesity and Type 2 diabetes, both of which contribute to liver cancer risk. Another factor may be the aging baby boomer population, which is made up of individuals born between 1945 and 1965.
About 75 percent of the HCV-infected individuals in the United States are baby boomers. The good news is that those infected with HCV can be treated and cured if the infection is detected. The bad news is that fewer than 13 percent of baby boomers have been screened for the virus, according to a study published last year in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research. This means that many chronically infected individuals are not receiving treatment that would cure their infection and decrease their risk of developing liver cancer.
What is the prognosis for patients with liver cancer?
Patients diagnosed with liver cancer face a grim prognosis. The five-year relative survival rate is approximately 18.4 percent, and it is even lower for those diagnosed with an advanced stage.
Other factors, such as race, may influence outcomes as well. Another study published in Cancer Epidemiology, Biomarkers & Prevention showed that U.S.-born and Puerto Rican-born black baby boomers had an estimated three- to four-fold greater liver cancer mortality rate than non-Hispanic whites.
While the prognosis for liver cancer is unfortunately poor, the good news is that multiple treatments, including regorafinib, nivolumab, and pembrolizumab, have been approved for liver cancer in recent years. The impact of these approvals on survival rates will become more apparent in the years to come.
Can liver cancer be prevented?
Given the grim prognosis for patients with liver cancer, we have to do more to lower the risk of developing this deadly disease in the first place. Many liver cancers could be prevented by lifestyle changes or by addressing existing medical conditions. Reducing alcohol and tobacco use, maintaining a healthy weight, and treating existing HCV/HBV infections are measures that can decrease the risk of developing liver cancer.
While Prometheus couldn’t prevent the daily assault on his liver, we may be able to do something to reduce the rising rates of liver cancer.
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