Another asbestos-related condition identified by Bologna researchers
Asbestos has long been accepted by the medical profession and toxicologists as one of the most dangerous carcinogens in common use
and is the cause of diseases such as mesothelioma and asbestosis and is strongly implicated as a cause of certain lung and other cancers.
Researchers from the University of Bologna's Department of Experimental, Diagnostic and Specialty Medicine have noted a high incidence of asbestos exposure among patients suffering from cholangiocarcinoma
, or bile duct cancer.
Between 2002 and 2008 cholangiocarcinoma, which globally affects 2 in every 100,000 people
, was identified in 258 of the department's patients. Of these, 24 – almost 10% – had at some time been exposed to asbestos either at home or at work
In 10 of the patients, there were no indications their cancers might have been caused through other conditions
, such as ulcerative colitis, Hepatitis C or alcohol-induced cirrhosis.
"We decided to conduct a case-control study to test the hypothesis that asbestos could be a risk factor for cholangiocarcinoma
," said the study's lead researcher, Dr Giovanni Brandi.
Since Dr Brandi's findings were published in 2009, his team has established a firmer connection between asbestos and cholangiocarcinoma by way of 155 study patients
with the cancer. Occupational histories of the subjects were collected in order to find out whether they had any history of exposure to asbestos.
Of those who did, a substantial proportion said they had worked in building and construction: an environment notorious for the persistent and long-term presence
On comparing the patients who had been exposed to a group which had not, the researchers concluded that people with a history of asbestos exposure were at greater risk of contracting
The risk was particularly marked with the 'intrahepatic' subtype of the disease, where cancers form in the ducts within the liver. With another 'extrahepatic' subtype, the external liver ducts are affected.
"These findings seem biologically plausible, since fibres are more likely to remain trapped
near the small intrahepatic bile ducts," Dr Brandi said.
Because they are usually inhaled, asbestos fibres tend to become trapped in the lungs and larynx. However, Dr Brandi thinks it is possible they can travel further
through the body to the liver. The fibres can cause constant inflammation once they lodge in the tissue.
"Asbestos fibres, after inhalation, can translocate to any abdominal organ," he said. "In particular, asbestos can deposit into liver tissue due to the high permeability of the small vessels."
Dr Brandi added that the carcinogenic process of the bile duct condition has been connected to the presence of a "chronic inflammatory stimulus" – such as asbestos.
Scientists are yet to identify conclusively all such inflammatory stimuli. However, they are aware that asbestos lodged in the body causes severe inflammation
, which could be among the 1st development stages for many diseases related to the material.
Additional stages can take up to 40 years with mesothelioma
. With Cholangiocarcinoma, the latency period could be just as lengthy, with the majority of diagnoses made in patients over 65
. If asbestos did cause bile duct cancer, this would suggest the last point of exposure had been several decades before.
Dr Brandi’s team has established a new research programme to look into the occupational and environmental causes
of cholangiocarcinoma, thereby confirming a possible link with asbestos. Its next stage will concentrate on the dose-response relationship between asbestos exposure and cancer risk.
Dr Brandi stressed that individuals who have been exposed to asbestos in the past should take further health precautions pending the results of his team's latest research.
"We believe that more studies need to be conducted
to properly address the issue of early diagnosis," he said. "Theoretically, sonography [ultrasound testing] could be studied as a first-line diagnostic approach in high-risk subjects."
Emma Costin, Head of Industrial Disease at Simpson Millar comments:
"When mesothelioma or asbestosis is suspected the treating clinicians will usually take a detailed occupational history
from the patient and these days will often advise them to seek independent legal advice. This is because the causative link between asbestos and these particular diseases is well known and the evidence is extremely strong in terms of the likely role of asbestos in causing the illnesses concerned."
"In this instance the new evidence suggests that the causative part played by asbestos and cholangiocarcinoma is stronger than had previously been recognised
, and thus patients newly diagnosed and with a clear history of working with asbestos would also be well advised to seek a legal opinion."
"Asbestos is not a naturally occurring mineral in the UK and since its danger even in small doses has been known for in excess of 60 years
, if a patient has come into contact with it asbestos at work there is a strong chance that this was in breach of employers duty. It is likely that each case would turn on its own facts, and medical evidence to establish the likely cause of an individual's illness would be needed in each case, however this should in no way deter patients from seeking advice. The new evidence is likely to be extremely helpful."