Treatments for malignant mesothelioma have not produced particularly satisfactory results over the past 25 years. The small number of past cases resulted in research dollars being placed elsewhere to study treatments for more common diseases. However, the number of cases is expected to increase over the next 10 to 20 years and researchers are trying to make headway in improving survival rates now to benefit those who will be diagnosed over the next couple of decades. What is known already is that multimodality treatments have led to the most success to date in terms of increasing survival rates and improving the quality of life.1
As medical researchers pursue a number of treatment avenues there are more questions than answers. The development of state-of-the-art treatments due to advances in gene therapy and molecular science have opened up new possibilities in terms of developing successful multimodality treatments. For example, what role can gene therapy play in targeting treatments? How can targeted chemotherapy treatments improve survival rates?
More Than One Treatment
There are currently several standard treatment options for mesothelioma including radiation, chemotherapy and surgery. Immunotherapy and gene therapy are also being used more frequently. Each of these treatments has its own benefits and can be effective curatively or for alleviating mesothelioma symptoms. In most cases however, these treatments are not used alone but rather a multimodality approach is taken.
Multimodality therapy simply means that more than one treatment is used. The general idea of a multimodality approach is that, while each type of mesothelioma treatment has its benefits, they each have their weaknesses too. If various treatments are used together, then the benefits of one treatment may overcome or compensate for the weaknesses of the other treatment/s.
Most conventional mesothelioma treatments come with unpleasant or dangerous side effects. Since multimodality therapy is utilizing at least two treatments, the side effects and risks a patient experiences will be greater. In some cases, the side effects of one treatment may amplify the side effects of another treatment. For example, chemotherapy can weaken a patient’s immune system. If chemotherapy is given as a multimodality therapy with surgery, then the patient may take longer to recover or have a higher risk of infection.
Multimodality therapy requires an individual approach for each patient. A doctor will analyze the patient’s condition and determine which treatments will be most effective when used together. For example, chemotherapy is often used before mesothelioma surgery to shrink a tumor, thus making it easier to remove. Chemotherapy may also be given after surgery (adjuvant chemotherapy) to destroy mesothelioma cells which may not have been removed during the surgery.
The use of adjuvant chemotherapy as a multimodality therapy is particularly beneficial for patients. Because the chemotherapy will destroy cancerous cells which have been left after surgery, surgeons are not as pressed to remove all potentially-infected tissues. Thus, they can remove smaller areas and leave more healthy tissues intact. For example, only part of a lung rather than an entire lung may be removed. This can significantly reduce complications for patients.
A group of Australian doctors reviewed 540 cases of patients who had malignant pleural mesothelioma looking for data that supported certain forms of treatments as being most effective. The patients experiencing the higher survival rates were those who were treated with an extrapleural pneumonectomy first which was followed up with radiotherapy after surgery. They were also given pemetrexed chemotherapy. The improved survival rates were deemed to be the result of four factors. They were, 1) the type of epithelial tumors, 2) the multimodality treatments, 3) the experience level of the surgeon, and 4) the pemetrexed chemotherapy.2 Determining the precise reason for increases in mesothelioma patients is not always easy due to lack of clinical data.
There is ongoing research on multimodality treatments for mesothelioma. For example, a recent study measured the effectiveness of combining radiation and the chemotherapy drug pemetrexed on malignant mesothelioma. The conclusion was that patients who were given both radiation and pemetrexed experienced better results than those receiving only one or the other. The irradiation enhanced the pemetrexed.3
The risks of undergoing multimodality mesothelioma treatments may outweigh the benefits in some cases. There is a higher morbidity rate with multimodality therapy than when single treatments are used. Further, multimodality therapy for mesothelioma can be financially, physically, and time demanding. However, as research advances the sophistication and effectives of treatments, multimodality approaches will become more common.
1 Martino, D. and Pass, H. Integration of Multimodality Approaches in the Management of Malignant Pleural Mesothelioma. (March 2004) Clinical Lung Cancer, v5:5, 290-298.
2 Yan TD, Cao CQ, Boyer M, Tin MM, Kennedy C, McLean J, Bannon PG, McCaughan BC. Improving survival results after surgical management of malignant pleural mesothelioma: an Australian institution experience. (June 2011) Ann Thorac Cardiovasc Surg, v17:3, 243-249.
3 Yoshida D, Ebara T, Sato Y, Kaminuma T, Takahashi T, Asao T, Nakano T. (Sept 2011) Interaction of radiation and pemetrexed on a human malignant mesothelioma cell line in vitro. Anticancer Research, v31:9, 2857-51.