Do Liver Flukes Cause Cancer?
Do liver flukes cause cancer?
If yes, what kind of cancers do they induce and what type of liver flukes are carcinogens?
You will find the answers in this article.
What is a liver fluke?
The liver fluke is a type of flatworm (trematode) that lives in the bile ducts, gallbladder, and liver of humans and some other mammals.
It causes lesions in these organs, resulting in parasitic disease.
Furthermore, the liver fluke has a complex life cycle that involves at least two hosts: an intermediate host (a snail) and a final host (a vertebrate).
What are the different types of human liver flukes?
There are two families of liver flukes: the Opisthorchiidae and the Fasciolidae, characterized by different life cycles and pathogeneses1.
Do liver flukes cause bile duct cancer?
When liver flukes infect humans, they migrate from the duodenum to the liver before settling in the biliary ducts1,2,3.
Long-lived flukes cause obstruction and chronic inflammation of the bile duct system, known as cholangitis3.
In heavy infections, this inflammation develops into a cancer of the biliary tract, known as cholangiocarcinoma2,3,4.
Which liver flukes cause bile duct cancer?
The following liver flukes can induce cholangiocarcinoma:
Clonorchis sinensis and Opisthorchis viverrini are classified as Group 1 carcinogens by WHO8,9.
By contrast, Fasciola hepatica and Fasciola gigantica have not been reported to cause cholangiocarcinoma.
Do liver flukes cause liver cancer?
Researchers have presented the case of a woman who suffered from multiple liver tumors caused by Fasciola hepatica13.
They did, however, not mention if the tumors were malignant or not.
Also, a study revealed that, in addition to inducing bile duct cancer, Opisthorchis viverrini may also cause liver cancer, including10
- Hepatocellular carcinoma
- Squamous cell carcinoma
Furthermore, Clonorchis sinensis has been shown to cause hepatocellular carcinoma11,12.
Do liver flukes cause pancreatic cancer?
Clonorchis sinensis has been shown to induce adenoma-carcinoma of the pancreas4.
Related: An Easy Way To Know If You Have Liver Flukes
What is ectopic fascioliasis?
Fasciola‘s migration out of the intestine and up into the liver is not always successful2.
Sometimes, the parasite gets lost and ends up in other organs, such as the2,17,18,19,20:
- Intestine
- Lungs
- Heart
- Brain
- Muscles
- Eyes
- Ovaries
- Lymph nodes
- Colon
A Fasciola infection that occurs outside the hepatobiliary system is known as ectopic fascioliasis2,14.
Does ectopic fascioliasis cause breast and colon cancer?
Researchers have reported the cases of patients suffering from breast14,15 and colon16 cancer who also had liver lesions caused by Fasciola hepatica.
They did, unfortunately, not try to identify a causal link between both diseases and a potential case of ectopic fascioliasis.
Can liver flukes cause cancer outside the hepatobiliary system?
Fasciola parasites have been described as the less harmful types of liver flukes.
However, if they could cause cancer, it would explain why some patients had breast, or colon, cancer in addition to Fasciola hepatica liver lesions.
Moreover, if Fasciola parasites can migrate to other organs than Opisthorchis or Clonorchisn that are carcinogens could possibly also do so.
Yet, at the current state of research, it has not been shown that liver flukes cause other cancers than hepatobiliary or pancreatic cancer.
Anti-liver flukes drugs have anti-cancer properties
Albendazole and mebendazole are two drugs used to treat parasites, including liver flukes21,22,23.
These drugs are active against several types of cancers, such as24
- Liver cancer
- Lung cancer
- Ovary cancer
- Colorectal cancer
- Breast cancer
- Head and neck cancer
- Melanoma
It suggests a potential role of liver flukes in these cancers.
Related: How To Get Rid Of Liver Flukes Naturally
Summary
Amongst the different types of liver flukes, Clonorchis sinensis, Opisthorchis viverrini, and Opisthorchis felineus, are the most aggressive ones, as they can cause bile duct, hepatocellular, and pancreatic carcinoma.
On the other hand, Fasciola hepatica and Fasciola gigantica can induce lesions and tumors in the liver but have not been reported to cause carcinoma.
At the current state of research, a direct causal link between liver flukes and cancers outside of the hepatobiliary and hepatopancreatic systems has not been demonstrated.
However, the fact that:
- Liver flukes can migrate to other organs
- Several patients with breast or colon cancer also had fascioliasis
- Drugs for liver flukes have anti-cancer effects
suggests that liver flukes may cause cancers other than hepatobiliary or hepatopancreatic cancers.
Nevertheless, further research is needed to confirm or rule out this hypothesis.
