So we've now discussed lung cancer which is the
commonest fatal cancer that affects any humans.
There is another cancer of the thoracic
cavity which is also very important but only
in a selected group of patients and that’s the mesothelioma.
This is a primary malignant tumour of the
mesothelium. It occurs due to asbestos exposure.
So people who have worked with asbestos or
breathing the asbestos fibers. Asbestos is
a mineral that was used a lot because it has
heat proof and fire proof properties.
However the fiber that it's made of are very
easily inhaled and once they reach the lungs
they can work their way through the alveoli and
eventually they work their way through to reach
pleura and over time they cause inflammation
of the pleura and eventually in some people that
will develop into a cancer called a mesothelioma.
So the striking thing about mesothelioma is
that it has a lag phase from exposure of asbestos
of about 20 to 40 years. So the patient’s
exposure occurred sometime before they present
with the disease. This means the mesothelioma
is disease that affects people who have worked
with asbestos and that tends to be middle
aged men who worked in building industries,
dockers, engineers, ship builders, boiler
makers. These are all industries that used
to in the old days use asbestos a lot.
The dose of asbestos exposure is related to
the risk of mesothelioma. So the higher the dose
the more chance you have developing mesothelioma.
But it is never a certainty. Most people who
worked at asbestos don’t develop mesothelioma.
Almost everyone who presents with mesothelioma
has worked with asbestos thing and therefore
identified while if you talked to the patient
about their occupational history.
How does it present? Early mesothelioma presents
as an exudative pleural effusion, so breathlessness.
But actually its frequently associated with
chest wall pain. It's quite hard to describe
chest wall pain which is diffused over one
side of the chest and the patient may have
the systemic symptoms that you often get with
cancer a weight loss and general malaise.
As the cancer develops the radiology becomes
more and more distinctive and this is associated
with extensive pleural thickening and that
constricts the lungs. So you get a lot of
lung volume loss as well. So you can see here on
the chest X-ray that there is a right-sided
pleural changes with thickening going up the
side of the chest and in fact if you look at the volume
of that right lung in chest X-ray, you see that
it looks a lot less than the volume of the
left lung. You can see that even better on
the CT scan image where the circumferential
thickening around the right lung and the inside
of it, the lung tissue, is only about
half the volume of the right side. That is
due to the mesothelium cancer cells spreading
along the pleura growing throughout, is a sheath
like cancer enclosing that lung and preventing
it from normally to expand.
So you need to think
about mesothelioma in
patients who have worked with asbestos and
who present with pleural effusions especially
if it is a painful pleural effusion. But to
diagnose it you need biopsies and that requires
a CT-guided or ultrasound-guided biopsies of
the pleura. Unfortunately the biopsies in the cells
are quite difficult to interpret and quite
often have to be repeated to get a confirmed
diagnosis. The disease itself is almost impossible
to cure and treatment is aimed at palliation.
So if somebody presents with a large effusion
and breathlessness as a consequence of that,
you can drain the fluid off and then you can prevent
the effusion from reforming by doing a pleurodesis,
a fusing of the visceral and parietal pleura,
probably best done by a surgical operation.
Patients with pain will get palliative radio therapy
and if you got a mass, because sometimes it
happens in the mesothelium erodes for
the chest wall that also will require palliative
radio therapy. There are chemotherapy agents
that are used for mesothelioma which seem
to have some effect where none of them have
had a dramatic effect.
Pain control is vital, so opiate painkillers
will be necessary and unfortunately the pain
is quite difficult to control even with opioid
pain killers. The median survival for mesothelioma
is about a year. It’s not long.