Treating Mesothelioma

Standard treatment options for mesothelioma are similar to the options for most other cancers. These are:

Because none of these treatments is very effective alone, multimodal treatment is often undertaken. Multimodal treatment employs surgery plus radiation and/or chemotherapy together when the disease is not too far advanced and the patient is healthy enough to tolerate it.

Other treatments intended to alleviate symptoms and pain include paracentesis and pleurodesis. These are discussed in the article on Pain Management in Mesothelioma.

Multimodal Treatment

Pleural mesothelioma is often diagnosed in its later stages when it has spread beyond the original tumor site. For patients receiving trimodal treatment with Stage 2 disease (lymph nodes involved), survival rates vary depending on the type of cancer cells. In one study, patients with the epithelial type had a 65% survival rate at 2 years versus 27% for those with sarcomatous or biphasic type. The 5-year survival rates were 27% compared to 0%.

Even when diagnosed in its earliest stages with the pleural tumor still localized (Stage 1), recurrence of the cancer following surgery is almost inevitable. Still, surgery combined with radiation and chemotherapy was successful in extending survival rates in early-stage patients. The median survival for patients with no lymph node involvement was 74% at 2 years and 39% at 5 years.

Another study of patients with localized peritoneal mesothelioma yielded a 79-month median survival rate following surgery and intraperitoneal chemotherapy. For patients with advanced disease, abdominal surgery is typically not considered adequate in removing the cancer cells. If performed, surgery is typically to help reduce symptoms and make the patient more comfortable, but does not significantly slow the progress of the disease.

Because pericardial mesothelioma is in the lining surrounding the heart, surgery is almost never a successful choice. If chemotherapy and/or radiation are chosen, it is often for palliative reasons (to reduce symptoms and make the patient more comfortable).

Types of Surgery

The objective of surgery is to remove the cancerous tumor and as much of the adjacent tissue as possible to which cancer cells are likely to have spread. In advanced stages of cancer, surgery is not an effective option because the cancer cells have become involved in too much tissue to be effectively removed or have spread to other parts of the body making local surgery pointless.

The two types of surgery for pleural mesothelioma are extrapleural pneumonectomy and pleurectomy

Extrapleural pneumonectomy is a radical procedure to remove part of the lung and its lining (pleura), the heart lining (pericaridium), and the diaphragm. This surgery is only effective when the disease is confined to the chest cavity. When combined with chemotherapy and radiation, it is not a cure but it has the potential to increase survival by two to three years. Because it is such an aggressive surgery, patients with weak heart or lung function are not candidates.

In very early stage disease when the tumor is still largely confined to the pleura, the surgeon may opt to perform a pleurectomy. Because this procedure involves removing a limited amount of tissue from the lung surface, recurrence of the cancer is high. However, this may be the only option for patients too weak to undergo more extensive surgery. When combined with chemotherapy and radiation, this treatment can reduce the patient’s pain and provide modest improvement in survival.

Because a pertinoneal mesothelioma tumor can be in any part of the abdominal lining, the procedure for removing the cancerous tissue is simply called debulking (or cytoreductive) surgery. The outcome of this procedure is better when the surgeon is able to remove the majority of the tumor. For larger tumors, surgery may be ineffective and not recommended.

Chemotherapy

Typical cancer chemotherapy involves taking powerful oral or intravenous medications that travel through the bloodstream to attack cancer cells. These systemic drugs often have nasty side effects such as nausea, fatigue, diarrhea and hair loss.

The standard chemotherapy drugs for mesothelioma and a few in late-stage clinical trials include:

Pemetrexed (ALIMTA®)
Ralitrexed (Tomudex®)
Ranpirnase (Onconase®)
Bevacizumab (Avastin®)
Vinorelbine, gemcitabine
Doxorubicin
Cisplatin, carboplatin and oxaliplatin (platinum compounds)

These drugs have different side effects and their effectiveness can vary under different circumstances. They are often used in various combinations and treatment schedules can differ significantly based on the treatment plan. Your doctor has to take these factors and your individual circumstances into consideration when determining the chemotherapy regimen that’s best for you.

A new type of chemotherapy used in mesothelioma treatment involves applying heated cancer-fighting drugs directly to internal tissues during surgery – referred to as hyperthermic intraoperative chemotherapy. This type of treatment only occurs when tumor removal surgery is performed. Its purpose is to apply high-dose chemotherapy directly to the tissues that may harbor microscopic remnants of cancer cells following surgery. The technique is effective and results in fewer drug-related side-effects to the patient. Nonetheless, standard chemotherapy treatment often follows.

Radiation

After surgery to remove a mesothelioma tumor, subsequent radiation therapy can significantly reduce the rate of local recurrence. Radiation inhibits a cell’s ability to divide and grow. Healthy cells are able to rebound from the effects of a limited amount of radiation that is sufficient to kill cancer cells. Radiation therapy is intended to extend survival by slowing the recurrence of cancer, but it has also been found to have some short-term benefit in reducing pain.

Ordinary radiation therapy uses an external machine to direct a beam of radiation at the location were malignant cancer cells are likely to remain. Treatment may be prescribed five days a week for five to six weeks. The short break in treatment each week gives the healthy tissue a chance to recover. Side effects can include sunburn-like reddening of the skin, inflammation of internal organs, and fatigue.

To reduce side effects, some treatment centers use 3-dimensional conformational radiation therapy (3D-CRT). This technique requires taking a full-set of CT scans of the area of the cancer. The resulting image data is fed into specialized computers that control the radiation delivery equipment.

Doctors and radiologists identify the precise areas in the scans to be targeted, and the 3D-CRT machine is able to deliver a very narrow beam to the designated areas with great accuracy. During a treatment session, the beam is aimed at the body first from one direction, then another. Periodically changing the path by which the beam enters the body minimizes the radiation’s effect on healthy tissue while consistently penetrating the target area each time. This reduces collateral tissue damage and side effects, and improves the treatment effectiveness.

An even newer therapeutic technique is called intensity modulated radiation therapy (IMRT). This technique also uses CT scans fed into computer systems to control multiple simultaneous radiation beams aimed at the cancer area from different angles. Alone, each low-intensity beam doesn’t cause significant damage to the tissue it passes through. At the location where the beams converge, however, the combined effect is much stronger.

References

Tan, Winston W., MD (2008), “Mesothelioma – Treatment and Medication.” Retrieved Dec 27, 2008 from the Medscape.com web site: http://emedicine.medscape.com/article/280367-treatment.

University of Florida Shands Cancer Center (2008). “Radiation Therapy for Malignant Pleural Mesothelioma.” Retrieved Dec 27, 2008 from the University of Florida Shands Cancer Center web site: http://www.ufscc.ufl.edu/Patient/content.aspx?section=ufscc&id=30346.

Multimodal Treatment

Types of Surgery

Chemotherapy

Radiation

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