Mesothelioma — No Stranger Among Older Adults
By David Yeager
Mesothelioma’s incubation period can range from 20 to 40 years, so it’s not unusual for patients between the ages of 60 and 80 to present with symptoms.
Mesothelioma is a rare but deadly disease. Although it shares some similarities, it is not a lung cancer. Typically, it’s a cancer of the pleural lining that surrounds the lungs, although it can occur in the peritoneal lining of the abdomen and rarely, in the pericardial lining of the heart. Because its incubation period is usually extremely long, adults over the age of 60 are disproportionately affected by it.
By far, the single biggest cause of mesothelioma is asbestos exposure, accounting for more than 90% of all cases although exposure to taconite or erionite fibers has also been identified as a potential cause. Additionally, some patients who receive intraoperative radiation therapy for Hodgkin’s lymphoma later develop mesothelioma, although research is ongoing. In the case of asbestos exposure, asbestos fibers migrate to the pleura for reasons not yet understood and initiate the process by transforming normal mesothelium cells into mesothelioma.
There are about 3,000 cases reported in the United States each year compared with around 200,000 cases of lung cancer. From asbestos exposure to disease onset, the incubation period is typically between 20 and 40 years, which is why most mesothelioma patients range in age from their 60s to their 80s. Occasionally patients in their 40s develop the disease, suggesting some type of childhood exposure.
Mesothelioma afflicts only between one and five people in 1 million, but survival rates are low. This is mainly because the condition often goes undiagnosed until its later stages, which limits treatment options. Diagnosis is difficult because the main symptom is shortness of breath, sometimes accompanied by a nagging cough and fatigue. Some people also report a sloshing sound in the chest when they jog or lie down. Often if the symptoms can’t be attributed to a cause, a chest X-ray is ordered to determine whether there is fluid on the lung. If fluid is present, a doctor should inquire whether the patient has worked with asbestos.
“If the patient is presenting with fluid on one side or fluid in the belly, then obviously an occupational exposure is very important because that will increase the chances that they have mesothelioma,” says Harvey Pass, MD, a thoracic surgeon and the director of the division of thoracic surgery at New York University Medical Center.
Although researchers are working to develop blood tests that can definitively identify mesothelioma, there are none that produce a reliable result. Doctors sometimes tap the lung fluid and check it for tumor cells, but the results are often falsely negative. The only reliable test is a thoracoscopy, or a direct pleural biopsy of the mesothelial tissue.
“The first thing is to find an expert who can guide the patient and the family through this process,” Pass says. “Get a second opinion at a major center that deals with a lot of mesothelioma cases because the protocols that are available as well as the expertise in dealing with a tumor that only involves about 3,000 patients in the United States calls for specialty management.”
Once a patient has been diagnosed, treatment depends on several factors. The stage of the cancer is one concern. Because it has few symptoms, mesothelioma often goes undiagnosed until it reaches stage 3 or 4. Although most patients are over the age of 60, age is not necessarily a barrier to aggressive treatment. Of more concern are physical condition and comorbidities. Often, problems such as heart disease or diabetes may make surgery, the preferred option, too risky.
“We’ve removed tumors off the lung in patients who are in their 80s, who have done well,” says David Sugarbaker, MD, chief of thoracic surgery at Brigham and Women’s Hospital in Boston. “It really has to do with what the physical condition of the patient is.”
Surgery with chemotherapy followed by radiation therapy is the most aggressive treatment, and it’s associated with the highest survival rates. There are two main types of surgery, depending on the size of the tumor. Either the tumor is peeled away from the lung or, if the tumor is large, part of the lung is removed. During surgery, chemotherapy—usually a drug called pemetrexed—is applied to the regions where tumors are most likely to recur.
But not all patients are candidates for surgery. Depending on the cancer’s stage and the patient’s condition, chemotherapy or radiation therapy alone may be used. Pass says there are also many experimental treatments being studied that target the proteins associated with mesothelioma, but they’re still in the early stages.
Pass says that surgery offers the best chance for extending a patient’s survival. The five-year survival rate for patients who don’t undergo surgery is around 5%, and only 15% to 20% of patients are candidates for surgery. But because of the difficulty diagnosing mesothelioma, only 10% to 15% of patients who receive surgery are in stage 1 or 2. It’s clear, though, that treating it as aggressively as possible benefits patients the most. The median survival time for untreated patients is seven to eight months. For chemotherapy alone, it’s 12 to 13 months, and surgery stretches it to 18 to 24 months. Pass adds that there are patients on both sides of the curve in those estimations, though.
Receiving a mesothelioma diagnosis is difficult, but patients need not give up hope. The treatments are evolving, the surgery is safer, and the chemotherapy is less toxic than it used to be. Sugarbaker expects treatment improvements to continue, and he says the outlook for survival is better than it’s ever been.
“We’ve made a lot of progress. I’ve been dealing with this problem for about 20 years now, and we’ve come a long way. Patients should realize that there is hope for recovery and quality-of-life extension,” Sugarbaker says. “When hope is part of the equation, anything is possible so people should be encouraged to seek treatment.”
— David Yeager is a freelance writer and editor based in Royersford, Pennsylvania.