Condition:
Lung Cancer
Contents:
What is lung cancer?
What are the symptoms associated with lung cancer?
How is lung cancer diagnosed?
What treatment options are available?
What is Cyberknife stereotactic radiosurgery and how might it be used to treat patients with lung cancer?
What is the patient process for lung radiosurgery using the Cyberknife?
What are the side effects of Cyberknife lung radiosurgery?
What is lung cancer?
Lung cancer is the most common cancer in the world and the leading cause of cancer death in the United States in both men and women. There were over 200,000 cases diagnosed in 2007 and the number of cases diagnosed each year continues to increase. Less than 15% of patients diagnosed live 5 years.
Increases in lung cancer risk are associated with exposure to cancer causing agents. The primary risk factor is smoking, but exposure to asbestos, radon, certain chemicals, chromium, nickel, and arsenic also increase risk.
What are the symptoms associated with lung cancer
Involvement of large airways can result in cough, wheezing, shortness of breath, coughing up blood, pneumonia or other infection. Tumors growing into bones or chest wall, or spread to other areas can cause pain. Unexplained weight loss may also be a symptom.
How is lung cancer diagnosed?
A detailed history taking and physical examination by a physician are two very important steps in evaluation. The chest x-ray is often the first study ordered and is often very valuable in the diagnosis. Computed tomography (CT or CAT scan) adds additional information about the tumor and if there is any possible spread to lymph nodes in the chest.
Needle aspiration/biopsy of lung tumors can obtain cells for positive identification of cancer. Using flexible fiber optic scopes, the trachea and airways can be examined and biopsies obtained for diagnosis. A small surgical incision and placement of a scope into the chest (mediastinoscopy) can evaluate lymph node spread and biopsies can be obtained.
Further scans and laboratory blood tests are generally ordered to evaluate for any spread of tumor outside of the chest area.
What treatment options are available?
Patients with stage I & II lung cancers, and are in good medical condition, usually are treated with surgery with very good results. In patients who are in poor medical condition for surgery, radiation therapy offers a curative alternative (including use of Cyberknife, discussed below). More advanced (stage III) disease must be evaluated on a case-by-case basis for the possibility of surgery. Generally, treatment is offered with chemotherapy and radiation combined (generally not with Cyberknife).
Some patients who have small tumors that could be resected but have medical problems or they refuse surgery. For these patients, primary radiation, often with the Cyberknife offers a curative approach. The earliest published data on radiation alone for lung cancer was published in 1960 by a group in London who showed nearly 50% 2-year survival. Drawing from this and later studies, Cyberknife users have applied stereotactic radiosurgery techniques to the treatment of lung tumors. Higher radiation doses can be delivered in single or several fractions and short-term outcomes are promising.
What is Cyberknife stereotactic radiosurgery and how might it be used to treat patients with lung cancer?
The Cyberknife is a radiation delivery system that consists of a linear accelerator radiation source mounted on a robotic arm. The robot arm allows the linear accelerator to deliver multiple (generally more than 100) highly focused beams of radiation that converge at the tumor site. The system integrates conformal therapy with accommodation for respiratory motion and real-time imaging.
This aggressive treatment with focused radiation has been very effective in treating many tumors in the past. Several recent studies have shown good response of lung tumors treated with the Cyberknife with low risk of treatment-related side effects. It is still early to determine tong-term effectiveness, but these early results have been promising, feasible, and safe. Further studies are in progress to determine the full potential of stereotactic radiosurgery in lung cancer therapy.
What is the patient process for lung radiosurgery using the Cyberknife?
Prior to radiosurgery, approximately 3-6 small gold seeds are implanted in or near the tumor to serve as markers. These markers can be seen on x-ray and the Cyberknife uses them to locate the precise location of the tumor three-dimensionally throughout the treatment.
The pulmonary medicine physician places the seeds through a needle under CT guidance about 10 days prior to treatment. This outpatient procedure takes about one hour. Approximately 1 week after the seeds are placed, a custom molded “cradle” is made for the patient to lie on during therapy. This ensures reproducibility of position. A CT scan is then done with the patient in the cradle and images are sent to the Cyberknife planning computer. A custom plan is devised according to patient and tumor anatomy.
The team involved in the procedure includes a radiation oncologist, radiologist, pulmonologist, nurses, physicist, dosimetrist, and radiation therapist. On the days of treatment, the therapy is delivered over 1 to 2 hours.
What are the side effects of Cyberknife lung radiosurgery?
In the majority of patients treated so far, most have experienced minimal side effects with the most common being fatigue. A dry cough can result from irritation of the airway and is usually not long lasting. Radiation pneumonitis is an inflammation type response and can occur, more commonly with larger tumors. It usually resolves without need for medical intervention, but may require medication. Special care must be taken with tumors near the center of the chest to limit dose to large blood vessels and airways.