Mesothelioma
Treatment by stage
Treatment depends on where the cancer is, how far
it has spread, and the patient's age and general health.
Standard treatment may be considered because of
its effectiveness in patients in past studies, or participation in a
clinical trial may be considered. Not all patients are cured with
standard therapy and some standard treatments may have more side
effects than are desired. For these reasons, clinical trials are
designed to find better ways to treat cancer patients and are based
on the most up-to-date information. Clinical trials are ongoing in
many parts of the country for many patients with malignant
mesothelioma.
Advanced Malignant
Mesothelioma (Stages II, III, and IV)
Treatment may be one of the following:
-
Draining of fluid in the chest or abdomen
(thoracentesis or paracentesis) to reduce discomfort. Drugs also
may be put into the chest or abdomen to prevent further collection
of fluid.
-
Surgery to relieve symptoms.
-
Radiation therapy to relieve symptoms.
-
Chemotherapy.
-
A clinical trial of surgery, radiation therapy,
and chemotherapy.
-
Chemotherapy given in the chest or abdomen.
Localized Malignant
Mesothelioma (Stage I)
The cancer is found in the lining of
the chest cavity near the lung and heart or in the diaphragm or the
lung. If the cancer is only in one place in the chest or abdomen,
treatment will probably be surgery to remove part of the pleura and
some of the tissue around it. If the cancer is found in a larger
part of the pleura, treatment may be one of the following:
-
Surgery to remove the pleura and the tissue
near it to relieve symptoms, with or without radiation therapy
after surgery.
-
Surgery to remove sections of the pleura, the
lung, part of the diaphragm, and part of the lining around the
heart.
-
External beam radiation therapy to relieve
symptoms.
-
A clinical trial of surgery followed by
chemotherapy given inside the chest.
-
A clinical trial of surgery, radiation therapy,
and/or chemotherapy.
Pleural mesothelioma
Pleural mesothelioma is of two kinds: (1) diffuse
and malignant (cancerous), and (2) localized and benign
(non-cancerous.)
Benign mesothelioma can often be removed
surgically, are generally not life-threatening, and are not usually
related to asbestos exposure. Malignant mesothelioma, however, are
very serious. Fortunately, they are rare - about two thousand people
are diagnosed with mesothelioma in the U.S. each year.
The remainder of this section is about diffuse
malignant pleural mesothelioma.
Pleural mesothelioma is a cancer of the cells
that make up the pleura or lining around the outside of the lungs
and inside of the ribs. Its only known cause in the U.S. is previous
exposure to asbestos fibers, including chrysotile, amosite or
crocidolite. This exposure is likely to have happened twenty or more
years before the disease becomes evident, since it takes many years
for the disease to "incubate." It is the most common type of
mesothelioma, accounting for about 75% of all cases.
Mesothelioma is sometimes diagnosed by
coincidence, before there are any symptoms. For instance, tumors
have been discovered through routine chest x-rays. However, when
symptoms occur, they may include shortness of breath, weakness,
weight loss, loss of appetite, chest pains, lower back pains,
persistent coughing, difficulty in swallowing, alone or in
combination. An initial medical examination often shows a pleural
effusion, which means an accumulation of fluid in the pleural space
- the area between the lungs and the chest wall.
The first step in detecting pleural mesothelioma
is, typically, a chest x-ray or CT scan. This is often followed by a
bronchoscopy, using a viewing scope to look inside the lungs.
The actual diagnosis usually requires obtaining a
piece of tissue through a biopsy. This could be a needle biopsy, an
open biopsy, or through a tube with a camera (thoracoscopy or chest
scope.) If an abnormality is seen through the camera then a tissue
sample can be taken at the same time, using the same tube. This is a
hospital procedure that requires anesthesia, but is not usually
painful. The tissue sample is tested by a pathologist.
Fluid build-up from the pleural effusion can
generally be seen on a chest x-ray and heard during a physical
examination, but a firm diagnosis of mesothelioma can only be made
through a biopsy and pathological testing. This is important because
there are also benign pleural effusions and other tumors that have a
similar appearance to mesothelioma. Diagnosing mesothelioma can be
quite difficult; it requires special lab stains, and much experience
in understanding them.
The spread of the tumor over the pleura causes
pleural thickening. This can reduce the flexibility of the pleura
and encase the lungs in an increasingly restrictive girdle. With the
lungs restricted, they get smaller and less functional, and
breathing becomes more difficult. At first a person with
mesothelioma may be breathless only when he or she exercises, but as
lung function drops, he or she can become short of breath even while
resting.
The tumor spreads by direct invasion of
surrounding tissue. As it spreads inward it can compress the lungs.
As the tumor spreads outward it can invade the chest wall and ribs,
and this can be extremely painful.
Current medical science does not know exactly how
and why, at a cellular level, asbestos fibers cause mesothelial
cells to become abnormal (malignant or cancerous.) Thus it is not
known whether only one fiber causes the tumor or whether it takes
many fibers. It seems that asbestos fibers in the pleura can start a
tumor as well as promote its growth; the tumor does not depend on
any other processes for its development.
There is as yet no known cure for malignant
mesothelioma. The prognosis depends on various factors, including
the size and stage of the tumor, the extent of the tumor, the cell
type, and whether or not the tumor responds to treatment. KMESA has
represented many clients who lived for five to ten years after
diagnosis, most of them in good health for a majority of those
years. Some mesothelioma victims succumb within a few months; the
average survival time is about a year.
The treatment options for people with
mesothelioma have improved significantly, especially for those whose
cancer is diagnosed early and treated vigorously. Many people are
treated with a combination of therapies, sometimes known as
multimodal therapy.
Specific types of treatment include:
There are also experimental treatments like gene
therapy and immunotherapy, angiogenesis inhibitors, and clinical
trials for various new treatments and combinations of treatments.
Treatments that reduce pain and improve lung
function, are becoming more successful (although they cannot cure
mesothelioma.) Pain control medications have become easier to
administer. Debulking is a surgical process of removing a
substantial part of the tumor and reducing the pleural thickening;
this can provide significant relief. X-ray therapy has also been
successfully used to control the tumor and the pain associated with
it for a while.
Peritoneal mesothelioma
Many of the organs in the abdomen are enveloped
by a thin membrane of mesothelial cells, known as the peritoneum.
Peritoneal mesothelioma is a tumor of this
membrane. Its only known cause in the U.S. is previous exposure to
asbestos, but it can be many years after exposure before the disease
appears. Peritoneal mesotheliomas account for about one-fifth of all
mesotheliomas.
Like pleural mesothelioma, peritoneal
mesothelioma can be either benign or malignant. This discussion is
only about malignant peritoneal mesothelioma.
Mesothelioma is sometimes diagnosed by
coincidence, before any symptoms have appeared. For example, the
tumor is sometimes seen on a routine abdominal x-ray for a check-up
or before surgery.
When the symptoms of peritoneal mesothelioma
appear, they typically include abdominal pains, weakness, weight
loss, loss of appetite, nausea, and abdominal swelling. Fluid often
accumulates in the peritoneal space, a condition known as ascites.
Over time the wasting symptoms can become more and more severe.
The growing tumor can exert increasing pressure
on the organs in the abdomen, leading to bowel obstruction and
distention. If the tumor presses upward, it can impair breathing
capacity. If the tumor pushes against areas with many nerve fibers,
and the bowel distends, the amount of pain can increase.
X-rays and CT scans are, typically, the first
step towards detecting peritoneal mesothelioma. The actual diagnosis
is typically achieved by obtaining a piece of tissue. The medical
procedure of looking at the peritoneum is known as a peritoneoscopy.
It is a hospital procedure and requires anesthesia. If an
abnormality is seen, the doctor will attempt to obtain a tissue
sample - this is known as a biopsy. The tissue sample will be
examined by a pathologist who makes a diagnosis using microscopic
analysis of specialized stains.
There are at least two explanations for how
asbestos fibers can get into the peritoneum. The first is that
fibers caught by the mucus of the trachea and bronchi end up being
swallowed. Some of them lodge in the intestinal tract and from there
they can move through the intestinal wall into the peritoneum. The
second explanation is that fibers that lodge in the lungs can move
into the lymphatic system and be transported to the peritoneum.
Medical science does not know exactly how or why,
at a cellular level, a carcinogen like asbestos causes a cell to
become malignant (cancerous.) Thus it is not known whether only one
fiber can cause a tumor to develop or whether it takes many fibers,
or what the exact conditions and predispositions are for this change
to happen.
At this time there are treatments, but no known
cure, for peritoneal mesothelioma. The prognosis depends on various
factors, including the size and stage of the tumor, its extent, the
cell type, and whether or not the tumor responds to treatment.
Benign Mesothelioma:
A rare form of mesothelioma is the cycstic
mesothelioma of the peritoneum. Its prognosis is benign. Its
occurrence has been described primarily in young women. However the
diagnosis presents difficulties, requiring extensive electron
miscroscopy and immunohistochemical studies.
Rare Sites:
Mesothelioma of the pericardium, is a very seldom
seen cardiac cancer. The mass is usually detected at a late stage by
echocardiography, the prognosis is very poor , with or without
therapy. Mesothelioma of the ovaries and the scrotum have also been
reported in the literature. The management differs based on the
stage of the disease, the prognosis is also very poor. The etiology
of the few cases of mesothelioma described in children remains
unclear and is not believed to be asbestos-related, the therapy and
prognosis differ on an individual basis.