..:: Pacific Heart Lung & Blood Institute ::..

Radiation Treatment

Radiation treatment is usually the last step in a tri-modal treatment approach for mesothelioma patients, and often follows surgery and chemotherapy. Full chest radiation destroys residual cancer cells that surgery and chemotherapy may be unable to eliminate.

Following the surgical removal of a lung in an extrapleural pneumonectomy (EPP) procedure, radiation has proven to be quite successful. Radiologists can readily administer the radiation without concern for damaging nearby organs because the lung has been removed.

Patients who have undergone the lung-sparing pleurectomy with decortication (P/D) procedure should take precaution in finding a radiologist. Because the lung is left intact, too much radiation can damage and complicate recovery. Work with your doctor to find an experienced radiologist who has treated other mesothelioma patients.

Intensity Modulated Radiation Therapy (IMRT)

Intensity modulated radiation therapy (IMRT) aims very small beams, or beamlets, at a tumor from many angles. IMRT delivers a high dose of radiation to the cancer while minimizing dosage to nearby sensitive organs. Each beam has a number of sub-beams or segments, and the intensity of each segment is varied according to the treatment plan.

During treatment, the radiation intensity of each beamlet is controlled, and the beam shape changes hundreds of times during each treatment. As a result, the radiation dose bends around important healthy tissues in a way that is impossible with other techniques. Because of the complexity of these motions, physicians use special high-speed computers, treatment-planning software, diagnostic imaging and patient-positioning devices to plan treatments and control the radiation dose during therapy.

For IMRT to be effective, the anatomical position of the tumor and surrounding healthy tissues must be accurately defined. Computed tomography (CT), positron emission tomography (PET) and magnetic resonance (MR) imaging provide the necessary three-dimensional anatomical information.

It's also important to accurately position and immobilize the patient during treatment. This may be done with special head frames (if the head or brain is being treated), or with advanced imaging devices such as electronic portal imaging and scanning ultrasound, which provide daily information about the location of internal organs. Some organs, such as the prostate, move due to normal daily volume changes in the bladder and rectum. Gold seeds may be placed into the prostate to track prostate movement daily and ensure more precise targeting.

A device called a multileaf collimator adjusts the size and shape of the computer-determined radiation beams. The collimator, a computer-controlled mechanical device, consists of up to 120 individually adjusted metal leaves. These leaves move across the irradiated tissue while the beam is on, blocking out some areas and filtering others to vary the beam intensity and precisely distribute the radiation dosage.

Radiation oncologists usually administer a regimen of IMRT treatments over four to eight weeks. The total dose of radiation and the number of treatments given depend on the size, location, and type of cancer; the patient's general health; and other medical therapy the patient is receiving.

Radiofrequency Catheter Ablation (RFA)

Ablation is a medical term that refers to any procedure performed to destroy diseased or damaged tissue in the body. Radiofrequency Catheter Ablation (RFA) is a technique in which a thin tube, or catheter, is inserted through the skin or threaded through the blood vessels to the site of disease. Extreme heat or cold, alcohol, chemotherapy drugs or other therapies are delivered through the catheter to the diseased tissue.

Specifically, RFA treats disease with heat, a technique preferred by many cancer experts because it can reliably destroy a small, targeted area of tissue without affecting healthy affecting structures beyond the treatment site. With RFA, the doctor can pinpoint target areas with accuracy while monitoring and controlling the temperature of heat therapy.

Interventional Radiology (IR)

Catheter ablation also can be performed by surgeons as a surgical procedure called intra-operative catheter ablation. There are a number of differences between surgical and interventional radiology (IR). IR treatment tools are usually inserted through a small nick in the skin. There are no surgical incisions, no stitches and no scars. General anesthesia is not needed for many IR procedures, and in most cases they are less painful and have fewer risks and complications than surgery.

Most conditions treated with IR can be done in an outpatient setting, or require hospitalization for only a brief time. Patients treated with IR can expect shorter hospital stays – and faster recoveries – than surgical patients. Many people resume normal activities within a few days after RFA or other IR procedures.

10-30-2006 - Radiation to Healthy Lung Associated with Pulmonary-Related Death in Post EPP Meso Patients (MD ANDERSON)

A new study reveals that fatal pulmonary-related events following radiation therapy are associated with the amount of radiation received by the contra lateral or healthy lung.

Researchers from Anderson Cancer Center in Texas investigated the incidence of fatal pulmonary events in 63 patients with mesothelioma who underwent intensity modulated radiation therapy (IMRT) and extrapleural pneumonectomy. Endpoints were pulmonary-related death, classified as death from pneumonia within six months of intensity modulated radiation therapy, or non-cancer death, including all deaths except those related to pulmonary-related death or cancer.

Researchers concluded that of the 10 percent of patients who died from pulmonary-related death, all had received significantly more radiation to their contra lateral lung, compared with non-cancer death patients.

1-25-2005 - Radiofrequency Ablation of Thoracic Lesions: Part 2, Initial Clinical Experience Technical and Multidisciplinary Considerations in 30 Patients

Objective

The purpose of our study was to report our initial experience with patients who underwent percutaneous imaging-guided radiofrequency ablation of thoracic lesions, and to emphasize technical and multidisciplinary issues and adjunctive procedures specific to thoracic tumor ablation.

Materials and Methods

Our cohort consisted of 30 patients with a spectrum of primary (n = 18) and secondary (n = 11) lung tumors, mesothelioma (n = 1), and five secondarily eroded, painful ribs who underwent ablation of 36 total lesions (one patient had two ablations). Patients either were nonsurgical candidates because of medical comorbidities or extent of disease, or had exhausted chemotherapy and radiation therapy options, or had refused surgery or undergone unsuccessful surgery. Patients were treated with radiofrequency ablation after agreement among oncologists, thoracic surgeons, and interventional radiologists. An array-style electrode under impedance control was used to treat 29 thoracic tumors and the adjacent rib metastases (n = 5). A cool-tip radiofrequency probe was used for two patients. CT guidance and general anesthetic were used for all but one patient. Sonographic guidance and IV conscious sedation were used in one patient. Pain (n = 11) and tumor cure or control (n = 19) were the primary indications for the procedures. Adjunctive procedures to the radiofrequency ablations included the creation of saline or water windows (n = 3); establishment of transosseous and transchondral routes (n = 4); use of intercostal and paravertebral nerve blocks (n = 15); and use of an intraprocedural catheter (n = 1), needle (n = 1), or sheath (n = 3) for treatment of pneumothoraces. Follow-up was from 2 to 26 months.

Results

All ablations were technically successful. No periprocedural mortality occurred. Necrosis of tumor was greater than 90% in 26 of 30 lesions based on short-term follow-up imaging (CT, PET, MRI). In the 11 patients who underwent ablation for pain, relief was complete in four and partial in the other seven. One patient developed a local skin burn, four patients had self-limited hemoptysis up to 4 days after ablation, one had transient atrial fibrillation, one developed hoarseness, and two patients were transiently reintubated after extubation. Eight pneumothoraces developed; one patient underwent placement of a chest tube. Four patients died within 1 year of ablation from extrathoracic spread of tumor.

Conclusion

Radiofrequency ablation for a variety of thoracic tumors can be performed safely and with a high degree of efficacy for pain control and tumor killing. The effect of ablation can be assessed with CT, MRI, or PET. Various technical issues differentiate thoracic tumor ablation from standard abdominal ablations. Numerous other thoracic interventional radiology procedures are beneficial to assist the radiofrequency ablation. A multidisciplinary approach offers valuable expertise for patient care.