SAN FRANCISCO--Although malignant mesothelioma, a tumor usually found in the pleurae, is still uncommon, its incidence has been rising over the past two decades, probably due to long-term exposures to asbestos, Henri G. Colt, MD, said at a panel session at the American Lung Association/American Thoracic Society 1997 International Conference.
Data from a registry of all patients diagnosed between 1974 and 1993 (3,324 cases) show that the disease is four times more common in men than in women and is most often diagnosed among whites. The tumors occurs in the pleurae in 86% of patients, in the peritoneum in 13%, and in other sites in 1%.
Pleural involvement tended to cluster in large seaport cities such as Seattle, Honolulu, and San Francisco, suggestive of asbestos exposures, possibly among Navy and shipyard workers, said Dr. Colt, associate professor of medicine, University of California, San Diego.
Several speakers on the panel noted that every proven diagnosis of malignant mesothelioma raises the specter of having to appear in court--because of litigation arising from asbestos exposure.
From 1974 to 1988, the disease incidence peaked at age 75 to 79 years, but from 1989 to 1993, the peak age jumped to the 80- to 84-year range. "Annual deaths from malignant mesothelioma will certainly rise during the next five years as our population ages, and physicians and surgeons will continue to see more patients with this disease in their practices," Dr. Colt said. Since there is no effective treatment, "this will present new, worrisome, challenges to physicians."
A Personal Crusade
Dr. Colt has embarked upon a personal crusade to call attention to the disease. "Physicians are frustrated because very little can be done for these patients," he said, "and patients feel stranded because they have no place to turn."
With an initial contribution from Oscar Gordon, "a valiant patient," Dr. Colt said, he has helped to establish the Oscar Gordon Memorial Fund, a charitable foundation set up to fund research and popularize information about meso-thelioma. Dr. Colt has also made videotapes, primarily for patients, telling them what to expect and where they can get help, "and hopefully to make them feel that they are not isolated in an indifferent world," he said.
One problem hampering progress with the disease is the lack of a good animal model. "You can't apply for NIH funding until you get a model," Dr. Colt said. Models are currently being developed by orthotopic transplantation--ie, the tumor is taken out of a patient and implanted into an immunocompromised laboratory animal.
"Once we get tumor models, we can proceed with development of gene therapies," he said. He noted that thoracos-copy, currently used to assist in diagnosis and in delivering palliative care, could potentially be used for intrapleural chemotherapy and the introduction of cyto-kines and tumor-fighting agents directly to the surface of the pleurae.