Cholangiocarcinoma: What is it and why is it so prevalent In Thailand?
By Imperial medical students Thomas Hughes and Thomas O’Connor
Today, 17th February 2016, marks the first ever World Cholangiocarcinoma Day.
Cholangiocarcinoma (CCA) is a primary liver cancer, usually formed from glandular structures in the epithelial tissue (adenocarcinomatous). It occurs in the bile ducts and is classed as being either intra-hepatic (IHCC) or extra-hepatic (EHCC) depending on whether the tumour forms inside or outside of the liver.
CCA is the second most common form of primary hepatic malignancies in the world, with survival beyond a year of diagnosis being <5%.[1] It represents 30% of primary hepatic malignancies with a mean survival rate of 3-6 months after diagnosis, due mostly to the late presentation of symptoms which massively reduces treatment success rates.[2],[3] In the western world the causes of CCA are not well known with 80% of cases being random with no specific risk factor. Despite this, several associations have led to risk factors being identified. The majority of risk factors are associated with chronic biliary inflammation, the most common of which is primary sclerosing cholangitis. The human pathogen Cryptosporidiosis has been associated with CCA and typhoid carriers have been found to have a six-fold increase in CCA. Aside from this, hepatitis B and C have both been found in higher proportions in the CCA population.
CCA is much more prevalent in south-east Asia, particularly north-east Thailand, than elsewhere in the world, with 80-90 cases per 100,000 people.1 The reason for the high incidence is due to biliary infestation with liver flukes, most notably Opisthorchis Viverrini (OV). OV has been recognised as a type 1 carcinogen since 1994 due to its role in causing inflammation of the bile ducts which leads to fibrogenesis and increasing tumorigenesis.3Oxidative stress has been proven to play a key role in transforming a chronic OV infection into CCA via advanced periductal fibrosis.4 OV makes it’s way into the human body via the consumption of raw or undercooked fish, a delicacy in Thailand, particularly in the Isaan region. (more…)