Hepatitis B and the Liver Cancer Endgame
Kristina Campbell in Nature: Liver cancer is the third leading cause of cancer deaths globally — and although rates of death from most types of cancer are decreasing, liver cancer is a notable exception. Rates of fatal hepatocellular carcinoma have risen sharply since the 1980s in the United States and elsewhere, and are projected to increase even further over the next two decades. Excessive alcohol consumption and metabolic disorders both lead to hepatocellular carcinoma, but at the root of most cases are viral infections of the liver. Hepatitis B, in particular, has no cure and is responsible for at least half of all hepatocellular carcinoma worldwide. So preventing cancer in people with hepatitis B could drastically decrease liver cancer cases worldwide — potentially saving around 800,000 lives per year. When someone’s liver is infected with hepatitis B, damage increases over time, as long as the virus is active. The liver tissue thickens and forms scars (fibrosis), advancing to severe scarring called cirrhosis. In approximately one-third of people with hepatitis B infection, this then progresses to hepatocellular carcinoma, as the viral DNA inserts itself into liver cells, changing their function and allowing tumors to grow.
Researchers and medical professionals cannot yet predict with certainty which people with hepatitis B infection will develop liver cancer. They know it happens more frequently in men, in people infected with certain genetic variants of the virus, in heavy consumers of alcohol, and in those who have been exposed to chemicals called aflatoxins, which can contaminate foods, including peanuts. People with various metabolic disorders are also at higher risk, and studies have identified human genes associated with this viral-led progression to cancer1. However, these risk factors fail to identify everyone who will get hepatocellular carcinoma. People with hepatitis B infection and liver damage should ideally be monitored regularly for evidence of tumors, because survival rates increase if the cancer is caught early. More here.
Lower chronic hepatitis B in South Asia despite all odds:
The South Asian countries, a contiguous block of countries which have been classified together as Global Burden of Disease Regions include Afghanistan, Bangladesh, Bhutan, India, Nepal and Pakistan. People in South Asia are at a higher risk of developing infectious diseases due to poverty and its associated problems of unhygienic living conditions, malnutrition, illiteracy, and poor access to clean water, toilet facilities, and quality health care. Spread of HBV infection in many South Asian countries is attributed to unsafe blood supply, reuse of contaminated syringes, lack of maternal screening to prevent perinatal transmission and delay in the introduction of hepatitis B vaccine. However, it is intriguing that bucking the trend of other infectious diseases, the prevalence of HBV in South Asian countries is lower than some of the more affluent neighbors in the South East Asian countries. Re-emphasizing the lower prevalence of HBV in South Asia is an article by Shrestha et al in this issue of Tropical Gastroenterology, which shows that the prevalence of HBV in Nepal is even lower than that in other countries of South Asia. More here.