Mesothelioma is a rare cancer that develops in the lining of the lungs, abdomen, or cardiovascular cavity. A 2017 study reported that the number of people affected by this rare cancer is between 2,400 - 2,800 individuals per year in the United States alone.
Cancer can impact anyone, whether it’s through a personal encounter or the story of a loved one. Each day there are more than 100 different types of known cancers that riddle the lives of people around the globe. Among the variety of cancers, some are well known while others can be considered less common. One rare cancer in particular that happens to be making great strides in the development of new treatment options and increased survival rates is mesothelioma.
What is Mesothelioma?
Mesothelioma is a rare cancer that develops in the lining of the lungs, abdomen, or cardiovascular cavity. A 2017 study reported that the number of people affected by this rare cancer is between 2,400 - 2,800 individuals per year in the United States alone. Known for the long latency period of 20-50 years, the average age of a mesothelioma patient is between 55-70 years old. With currently no known cure, prognosis remains poor, with most patients living less than a year from diagnosis. There are three known types of mesothelioma: pleural, peritoneal, and pericardial. Each type results from different sources of exposure and impacts different regions of the body.
Pleural mesothelioma is the most common type of mesothelioma, developing in the lining of the lungs and chest walls and brought on from inhalation of asbestos fibers. Peritoneal mesothelioma is caused from ingested asbestos fibers that become trapped in the lining of the abdomen. Pericardial mesothelioma occurs when asbestos fibers get lodged in the pericardium or the lining of the heart cavity. Malignant mesothelioma is extremely aggressive and has a long latency period, which means it usually remains undetected until the cancer has reached an advanced stage.
Early detection is key to a longer lifespan as treatment options have improved vastly. Although the cancer itself is rare, the number of options for treatment continues to grow. Researchers are hard at work combining treatment methods with a multitude of customized plans.
Treatment Options: Current & up-and-Coming
Chemotherapy is one of the most common forms of treatment for patients diagnosed with mesothelioma. The two methods of chemotherapy that are used to treat this cancer are referred to as systemic chemotherapy and intraoperative chemotherapy.
Systemic chemotherapy is administered orally using pills, or intravenously. The drug treats the entire body by directly entering the bloodstream and traveling to attack cancer cells. For intraoperative chemotherapy, the drugs are typically warmed up and directly target the organs where the tumors develop. A single dose of this treatment is often administered in the operating room after surgery is performed to remove a mesothelioma tumor. More often than not, this method is used to help treat pleural and peritoneal mesothelioma. Intraoperative chemotherapy has been noted to have fewer side effects on a patient than systemic chemo. Intraoperative treatment has also seen wonderful results, gaining popularity in recent years, while systemic chemotherapy has been proven to kill healthy cells alongside the cancerous ones. Either or both of these methods may be used in conjunction with surgery and/or radiation, depending on the individualized treatment plan.
Alimta® (pemetrexed), marketed and manufactured by Eli Lilly and Company, is the first mesothelioma chemotherapy drug that has been approved by the Food and Drug Administration (FDA). Alimta® was developed in 2000, and is administered over a 21-day period. Alimta® has been approved to be used as a single agent, or combined with another drug called Cisplatin®, known as the penicillin of cancer. Alimta® is administered intravenously with Cisplatin® infused in only the first day of treatment, and then not again until the 22nd day. The combination of these two drugs has been known to prolong a patient’s life up to several months, while also controlling common symptoms like pain and discomfort and managing breathing difficulties.
Avastin® (bevacizumab), a Genentech drug, works by preventing new blood vessels from forming, effectively starving the tumors. This is typically seen as a second-line treatment in conjunction with a standard chemotherapy. July of 2016 was the first instance that the National Comprehensive Cancer Network (NCCN) updated its regulations for Avastin® combined with chemotherapy for patients dealing with non-operable pleural mesothelioma.
Radiation therapy works by damaging the DNA to limit the growth of mesothelioma cancer cells, but this form of treatment can only be used in secondary nature to act and assist other forms of treatment like chemotherapy and palliative surgery. Radiation can be destructive to healthy tissues, which is why it is only targeted to the specific parts of the body where the cancer exists.
Two types of radiation are used for mesothelioma patients; one is external beam radiation, which targets a specific locale to stop or slow the growth of malignant cells. Secondly, brachytherapy is a temporary type of treatment that delivers high doses of radiation directly to the tumor inside the body, and the applicator may be left in place until the seeds are removed. Radiation is used for three main reasons: to help create a more effective treatment process, to work as a preventive agent for further development (in tumor size or quantity), or to assist in the reduction of pain throughout the treatments entirety.
Gene therapy is designed to fix the genetic function of a cell. Cancer in any part of the body is brought on by an abnormal cell mutation, and therapy of this nature works to remove the incorrect genes and replace them with functioning ones. Clinical trials are still in process, and gene therapy is being studied and evaluated for effectiveness at treating mesothelioma in particular. However, agents like Onconase® (ranpirnase) were granted orphan drug status in 2007, which means it’s been specifically designed (and proven effective) to treat rare diseases and cancers. Other drugs that have been documented to have similar success during gene therapy include thalidomide®, an Immunomodulator, and a statin, lovastatin®. All three have been introduced both alone and combined with chemotherapy.
Immunotherapy enhances the body’s immune system and is increasingly showing promising results for mesothelioma patients. Treatments that make use of Keytruda® (pembrolizumab), a drug developed by Merck & Co. that works to target the PD-1/PD-L1 pathway of cancer cells, which in turn activates programmed cell death in those cells. In early clinical trials undergone by mesothelioma patients, Keytruda® saw success in roughly 76 percent of the treated patients among 25 total participants. 48 percent experienced no increase in the current extent of their tumors, and 28 percent saw some form of shrinkage in tumor size.
Another immunotherapy drug known as Opdivo® (nivolumab) has been developed by Bristol-Myers Squibb. It works similarly to Keytruda®, as a checkpoint inhibitor, and is in Phase III trials. Opdivo is approved by the FDA for some conditions, and is currently being studied in a clinical trial for mesothelioma. This drug is making great headway for malignant pleural mesothelioma cases.
Photodynamic therapy uses light, and drugs known as photosensitizing agents, to kill cancer cells and stop cancer from spreading. Patients who undergo this form of therapy might receive the drug Photofrin® developed by Pinnacle Biologics in a two-step process. First, they will enter into an outpatient treatment area to have the drug injected directly into the bloodstream. After the first administration, a patient will then return to their doctor, who will treat the exposed tumor(s) by use of a laser light. This process takes anywhere from 5 to 45 minutes depending on the size and/or number of tumors. Up to 5 days later, the patient will receive an endoscopy to remove any of the dead tissue that results from the procedure. Side effects include discomfort, swelling, bruising, and light sensitivity up to 30 days after treatment.
Steps Towards a Cure
Although upwards of 15,000 Americans lose their battle each year to mesothelioma, our generation of medical professionals and cancer researchers are determined to find a cure for this rare disease. With higher rates of exposure and diagnoses comes an increased level of concern and medical development determined to halt the statistics at large. Early detection will continue to yield the most diverse and effective treatment options available. To learn more about mesothelioma and the positive treatment developments, follow the Mesothelioma Cancer Association and explore insightful survivor stories.
This content was contributed by Emily Walsh, Community Outreach Director, Mesothelioma Cancer Alliance.
