Two new protocols, involving two separate types of mesothelioma, offer better hope for survival for patients of this dread form of cancer.
Mesothelioma, a cancer of mesothelial tissues, occurs most commonly as (malignant) pleural mesothelioma, in the lungs – in about 75 percent of cases – followed by peritoneal mesothelioma, in the abdomen. Pericardial mesothelioma, which occurs in the protective membrane around the heart, is the least common, at less than one percent of cases.
The first discovery focuses on diffuse malignant peritoneal mesothelioma, or DMPM, which occurs in about 10 to 20 percent of cases of mesothelioma. The revolutionary new treatment, discovered by researchers at Royal Prince Alfred Hospital in Sydney, Australia, and published in the Journal of Clinical Oncology, describes a process using combination therapies involving surgery and chemotherapy.
Discovered by T. D. Yan and colleagues, this use of reductive surgery, closely followed by a chemotherapy treatment in which the chemical is heated before being injected into the peritoneal cavity, has been shown to be more effective than traditional IV chemotherapy.
Researchers believe this is because the heated chemical reaches more areas inside the abdomen, killing more of the cancer cells that escape surgery – cells which can form new tumors if left unattended.
The study which led to the process involved more than 400 patients with peritoneal mesothelioma. Of that 400, the overall median survival rate was 53 months, or 4 years and five months, with three- and five-year survival rates of 60 percent and 47 percent respectively.
This compares quite favorably with historical survival rates, which predict 90 percent of mesothelioma victims surviving up to 18 months with one or more treatment modalities, and 10 percent surviving about 5 years. Untreated, 66 percent of peritoneal mesothelioma victims die within the first year.
Mesothelioma in general responds better to multi-modal therapies; that is, surgery followed by radiation and/or chemotherapy. Multiple chemotherapy agents have been proven slightly more effective than single agents, and today the typical chemotherapy regimen is pemetrexed combined with cisplatin.
Because of mesothelioma’s long dormancy period, which can extend up to 50 years, many mesothelioma patients are elderly. Others have been progressively weakened by the disease’s spread. In general, these patients are not strong enough to undergo multi-modal therapies and many choose alternative therapies like diet modification, massage, acupuncture or even herbal therapy to relieve side effects and symptoms.
The second discovery, in the UK, involves a vaccine which has shown promise in initial clinical trials.
This vaccine, based on the principle of dendritic cell immunotherapy – using the body’s own defenses to fight disease – involves taking mesothelioma patients’ immune cells, mixing them with protein markers taken from the tumor, and injecting the result back into the patient.
The result is that T-cells – the major component that the immune system uses to fight disease – then attack and eat away at the tumor.
The discovery, and the vaccine, follows on research at the Erasmus Medical Center in the Netherlands, where DC (dendritic-cell) vaccines were shown to incite an anti-tumor response in mice.
The UK protocol will be the first test on humans, and it is hoped that the treatment – involving three progressive injections over a two-week period, on 10 mesothelioma victims, with what researchers are calling KLH (for “keyhole limpet hemocyanin”) protein markers – will show similar beneficial action to that displayed among the mice.
Results, published in The American Journal of Respiratory and Critical Care Medicine, showed that all ten study participants produced antibodies to the KLH markers, demonstrating that the protocol did indeed generate an immune response. Additional observation also showed that three of the tumors were reduced, though researchers were hesitant to ascribe this result to the vaccine therapy.
Equally as important, none of the 10 developed serious side effects to the vaccine, and the initial, flu-like symptoms disappeared on their own within a day.
Although the cohort was small (10 as compared to 400), both Dr. Joachim Aerts of Erasmus and Dr. Jodie Moffat of Cancer Research UK felt the results warranted further investigation.