Mesothelioma – A Poorly Understood Cancer

Today is national mesothelioma awareness day which is fitting because so few know what mesothelioma is or its impact on its victims. Mesotheliomas are rare tumors caused predominantly by exposure to asbestos. This cancer is hard to diagnose early and harder still to treat effectively but there are advances coming and multi-disciplinary care along with good palliative care can markedly improve overall treatment.

They mostly occur on the lung lining (pleura) but can occasionally develop on the heart lining (pericardium) or elsewhere. Although the latency period from exposure to diagnosis is usually very long, often 50 years or more, once symptoms occur, the disease is often aggressive and rapidly fatal. Many people were exposed to asbestos either at work or from home exposure to a worker, but only a small minority develops the disease. The type and quantity of exposure along with some genetic predisposing factors and possibly a co-carcinogen in the form of the simian virus 40 (SV 40 was found in polio vaccines in the 1950s and 1960s because the vaccines were manufactured in monkey cells that harbored the virus) are important. Once inhaled, asbestos fibers are not removed by the lung clearance mechanisms and some may make their way to the pleura where they can slowly lead to cancer development. (It should be noted that asbestos also predisposes to lung cancer and in combination with smoking the incidence of lung cancer rises substantially.)

Mesothelioma lies dormant for years and symptoms begin only when the disease has progressed substantially. Most early symptoms are very nonspecific such as chest pain or shortness of breath. The symptoms are often related to the development of a pleural effusion (fluid between the chest wall and the pleural lining of the lung), itself a sign that the disease has progressed. There are no good early diagnostic tests. Chest X-rays and CT scans are used but by the time the cancer is visible, it is often far progressed.

Unfortunately, treatment of mesothelioma is at best disappointing. Most individuals die within a short time after diagnosis. Surgery alone has a limited role because the disease has too often progressed for surgery to be useful but as noted below it is important to “debulk” the tumor before beginning drug therapy. Radiation therapy alone as well has limited value because of the spread of disease but has a role in local control. A more systemic approach is generally needed with chemotherapy but no drug or drug combination has been found to have truly major effects. That said, the combination of cisplatin and pemetrexed has been found to give an objective response in nearly 50% of patients, a doubling of the best response rates seen previously with a single drug. Responding patients live longer and have an improved quality of life despite the temporary side effects of the drugs. Other combinations are being tested continuously and there is reason to hope for further improvements. The use of genomic analyses and from that a more targeted drug approach may well be developed in the coming years. Since it has been shown that reducing the bulk of the tumor improves survival, most treatment today combines surgery to remove as much tumor as possible followed by radiation to further eradicate the tumor locally and chemotherapy for the disease beyond their reach.

An important element in care is to be treated by a multi-disciplinary team. Look for it and accept no substitutes. For example, at the University of Maryland Greenebaum Cancer Center, a patient with suspected or known mesothelioma is seen concurrently by a thoracic surgeon, a radiation oncologist, a medical oncologist and a nurse practioneer. After examining the patient and reviewing all of the laboratory and radiographic tests, the team presents their combined recommended plan of care, taking into account the patient’s preferences and family situation. It is definitely better care and I recommend that anyone with a chronic illness, not just cancer, seek out care in a team based environment, in concert with your primary care physician as the quarterback.

All patients can benefit from a good program of supportive or palliative care, begun at the time of diagnosis. Support groups, attention to pain management, assistance in finding financial and insurance assistance and psychosocial assistance to both patient and family can markedly improve the quality of life. Complementary medicine approaches can be very helpful as well such as acupuncture or relaxation exercises to help reduce the sense of breathlessness that can accompany mesothelioma progression.

In sum, mesothelioma is a disease that is difficult to diagnose early and once symptoms occur is difficult to treat effectively. Nevertheless, there is a lot of research underway looking at prevention, early diagnosis and improved methods of treatment along with maximizing supportive care. So there is real reason to be upbeat about the future. In the meantime, there are groups that offer education and support including Mesothelioma Resource Online (sponsored by a law firm) and sites such as that of the Mayo Clinic that have good overviews. And treatment centers that use the multi-disciplinary team approach can offer superior care.