What is Mesothelioma?
Mesothelioma from the (Greek meso+ thelioma, tumor of
middle lining tissue) is an uncommon cancer, originating from the cells which
form the membrane lining the abdominal cavity (peritoneal membrane or
peritoneum) which houses the intestines, or the chest (pleural membrane or
pleura) cavity housing the heart and lungs, in which the cells making up those
tissues begin to grow out of control.
Mesotheliomas most often are seen in older patients, more often men that have a history of occupational exposure to asbestos, although other causes such as
radiation and certain viruses have occasionally been implicated. In a proportion
of cases, no asbestos exposure can be identified.
Mesotheliomas involving the lung and pleura characteristically present as
progressive shortness of breath due to the thickening of the lining membrane of
the lung with gradual contraction of the breathing space; often, fluid
accumulates in the lung spaces as well, further interfering with breathing,
Mesotheliomas involving the abdominal cavity present with digestive symptoms,
and abdominal swelling due to thickening of the lining membranes of the gut, and accumulation of large amounts of fluid in the abdomen.
How serious is it ?
Mesotheliomas are serious and potentially life-threatening. Survival of patients with mesothelioma is usually short if effective treatment is not found, especially those with tumors that can be shown to be growing aggressively. Because mesotheliomas have usually spread throughout the pleural or peritoneal cavity before the diagnosis is made, complete surgical removal is only rarely possible. Moreover, mesotheliomas are not as sensitive to radiation therapy or chemotherapy as are many other tumors.
How are mesotheliomas diagnosed?
In all cases, the diagnosis of mesothelioma must first be unquestionably established by biopsy of affected or suspicious tissues, and by definitive microscopic examination by a trained pathologist. Biopsy almost always requires an invasive procedure such as thoracoscopy and pleural biopsy, or laparotomy or laparoscopy, The removed tissues may be treated with special biological or chemical stains which are used to help the pathologist establish a firm diagnosis. The pathologist usually also comments upon the rate of growth and biological virulence of the tumor
Second, the tumor must be staged if possible by X-ray, CAT scan, MRI or other
types of scans to clarify its location within the body, and to estimate the
likelihood of effective curative or palliative therapy. Staging of mesothelioma
by x-ray measurements, however, is difficult and often unreliable.
How are mesotheliomas treated?
A treatment plan is devised depending upon the mesothelioma type, aggressiveness, primary location, and degree of local (rarely, distant) spread. The treatment of pleural mesothelioma is difficult. Treatment with surgery, radiation therapy or chemotherapy used alone or in combination may be proposed, depending upon the potential benefits and risks of each modality. Surgery is rarely used alone, but sometimes suffices when only a small pleural patch of mesothelioma is detected, thus allowing visually complete removal of the tumor. More often, mesotheliomas of the left or right pleural cavity cannot be completely removed without taking the entire lung (pneumonectomy) on the same side as well. In such cases, radiation therapy and/or chemotherapy is given postoperatively to help eradicate any residual mesothelioma that may have escaped the surgeon.
The treatment of peritoneal mesotheliomas is even more problematic; until
recently no consistent treatment was available. At our institution, peritoneal
mesotheliomas have been managed in the experimental setting with combined
modality treatment consisting of extensive (usually not complete) debulking
surgery, followed by intraperitoneal and systemic chemotherapy followed in turn
by whole abdominal radiation therapy.
Because mesotheliomas now represent less than one percent of cancers and and are infrequently seen in the practice of most community oncologists, finding the
correct treatment can be very difficult. Proper management of mesotheliomas
often requires evaluation at larger tertiary hospitals or Comprehensive Cancer
Centers by specialists in medical, surgical and radiation oncology with
experience in all aspects of the clinical care of mesothelioma patients,
including the newest experimental treatments.
