LUNG CANCER

Description

Lung cancer is the number one cause of cancer deaths among men and women in the United States. There are two major types of lung cancer: small cell and non-small cell. Non-small cell makes up about 80 to 90 percent of the cases; small cell, approximately 10 to 12 percent. Both arise from lung epithelial cells.
Symptoms of lung cancer can include a cough that won’t go away, chest pain, hoarseness, shortness of breath, bloody or rust-colored sputum and recurring infections such as bronchitis and pneumonia.

Statistics

In 2005, an estimated 172,570 new cases of lung cancer will be diagnosed, making it the second most commonly diagnosed cancer in the United States and accounting for 13 percent of all cancer diagnoses. In men, the incidence rate has declined significantly, going from 102.1 cases per 100,000 in 1984 to 77.7 in 2001. The incidence rate in women has also declined for the first time after a long period of increase, from 52.8 cases per 100,000 in 1998 to 49.1 in 2001.
An estimated 163,510 individuals will die from the disease – about 29 percent of all cancer deaths. Among all patients with lung cancer, 42 percent are alive after one year – an increase from 37 percent in 1975. Still, the relative five-year survival rate for all lung cancers combined is only 15 percent. While 49 percent of individuals live at least five years when their cancer is diagnosed early and remains only in the lungs, very few cancers – about 16 percent – are detected at this stage.
In 1987, lung cancer surpassed breast cancer as the leading cause of cancer death each year in women. Lung cancer death rates in women have recently leveled off after decades of continual increase. In contrast, death rates in men have dropped by about 1.9 percent a year since 1991.

Early Detection and Diagnosis

It is extremely difficult to detect lung cancer early. If lung cancer is suspected, a chest X-ray or a spiral CT (computed tomography) scan will be taken to look for a spot or mass on the lungs, or for lung tumors or metastatic disease. Improvements in computer imaging and particularly spiral CT allow physicians to see a more detailed cross-sectional view of the lungs, and have improved detection of early stage lung cancer. If something suspicious is found, then a bronchoscopy, which involves a lighted scope being placed into the lungs, may be performed to confirm the diagnosis. Innovative technologies involving fiber optics are being developed that uses laser light with bronchoscopy to identify early lung cancer and as well as precancerous changes in cells; the technology can be used as a research tool for diagnosis and prevention. A lung tissue biopsy may be performed to look for cancer cells in the phlegm and lung tissue as well.
In 2004, the U.S. Preventive Services Task Force, on the basis of results of several studies, upgraded its recommendations regarding the use of spiral CT in routine screening. The group said that there was not enough evidence to date to recommend for or against routine screening in individuals who do not have symptoms.
A large, randomized clinical trial called the National Lung Screening Trial is trying to determine whether taking spiral CT scans of people at high risk will save lives. The trial, which started in 2002, involves some 50,000 people. The International Early Lung Cancer Action Project involves 27,000 individuals enrolled in a clinical trial at 30 sites on three continents. Preliminary results from the first 20,000 enrollees found a stage I lung cancer detection rate of 82 percent. Some 96 percent of the patients were cancer-free up to 100 months after surgery.

Minimizing Risk/Prevention

Approximately 85 to 87 percent of all cases are caused by tobacco use, making lung cancer one of the most preventable cancers. Another several percent stems from radon exposure. Individuals who have been smokers and asbestos workers have a much higher risk of dying of lung cancer.
In the last decade, researchers have identified many of the genes involved in the development of lung cancer. They have found that turning off the activity of certain cancer-blocking genes called tumor suppressor genes such as p53 and Rb, and turning on various cancer-promoting genes such as c-myc, ras and bcl-2 may play roles in triggering lung cancer. More recently, scientists have identified a gene associated with a cluster of inherited lung cancer. The challenge remains for researchers to turn this knowledge into advances in diagnosis, therapy or prevention.

Latest Research

Scientists are beginning to further develop and refine tools such as spiral CT that allow physicians to more routinely detect lung cancer. Innovations in radiation therapy for small volume lung cancers is one area that will continue to be explored, while the development of molecularly targeted, low toxicity adjuvant therapy for early cancers will be extremely important to manage such lung cancers.
Targeted therapies such as Iressa (gefitinib) and Tarceva (erlotinib) have shown some promise in clinical testing. These drugs are called EGFR (epidermal growth factor receptor) inhibitors, and they work by blocking a signaling pathway that cancer cells need to grow.
Iressa was approved by the FDA in May 2003 for patients with advanced non-small cell lung cancer whose tumors continue to grow despite chemotherapy. A randomized study last year by the National Cancer Institute of Canada Clinical Trials Group showed that patients given Tarceva (approved by the FDA in November 2004) after chemotherapy for advanced NSCLC lived longer than those who didn’t receive the drug. Patients with advanced disease generally only live a few months.
Scientists have known it is effective in only 10 to 15 percent of individuals who take it. A series of studies last year showed that certain mutations in EGFR tumors were associated with higher response rates to drugs such as Iressa and Tarceva.

Current Treatment

Lung cancer is notoriously difficult to treat effectively. There are three standard ways to treat lung cancer: surgery, radiation therapy and chemotherapy. Tumor type, size and location determine the necessary treatment. While the most common type, NSCLC, is treated with surgery whenever possible, lung cancer is usually diagnosed after it has spread to other areas in the body, making a cure nearly impossible. Despite surgery that apparently removes all of the cancer, it nearly always comes back in the lung or elsewhere, such as the bone or liver.
Early-stage (stages I and II) NSCLCs are usually treated with surgery and often followed by chemotherapy. In some cases, radiation is used. In stage III, where some cancer cells have traveled to the lymph nodes, chemotherapy is typically required. But such patients are at risk for having the cancer return, and doctors may delay surgery until they can see if the chemotherapy has been effective in shrinking the tumor.
Individuals with lung cancer deemed inoperable (stage IIIB) may receive both chemotherapy and radiation if the cancer has not spread to other areas. Most patients with stage IV lung cancer or stage IIIB in which cancer cells are in the fluid around the lung – are very likely to have disease that has spread to other areas in the body and are treated with chemotherapy.

They are rarely “cured.”

Some recent important advances have been made in treating early-stage NSCLC. In 2004, a pair of clinical trials by the National Cancer Institute of Canada and the Cancer and Leukemia Group B, respectively, showed that adding chemotherapy after surgery in early-stage NSCLC helped individuals live significantly longer. Similarly, two recent randomized trials of adjuvant chemotherapy after surgery for early-stage lung cancer also showed the importance of adding chemotherapy for the first time in lung cancer, and have changed the standard of care for such disease.
One innovation in the clinical trial setting is the so-called window of opportunity trial. In such studies, investigators give experimental therapeutics to lung cancer patients who have a two-to-four week period of time prior to surgery. Such drugs have already shown some favorable results and low toxicity. Researchers then can evaluate the drug’s effects on tumor size and biology.

Resources

National Cancer Institute1-800-4-CANCERhttp://www.cancer.gov/
American Cancer Society1-800-ACS-2345http://www.cancer.org/
American Lung Association1-800-LUNGUSAhttp://www.lungusa.org/
Alliance for Lung Cancer Advocacy, Support, and Education1-800-298-2436http://www.alcase.org/
Lung Cancer Onlinehttp://www.lungcanceronline.org/