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Friday, August 29, 2014
Lung cancer is an epithelial (surface lining) neoplasm (tumor) of the lung. There are 2 major types of lung cancer: Small cell cancer (accounting for 15% of primary lung cancers) and Non-small cell lung cancer (in the remaining 85%).
Small cell cancer is a neuroendocrine tumor (this refers to the type of cell that a tumor grows from not the location) characterized by rapid growth, early metastasis (spread via lymphatic or blood vessels) and overall poorer chance for cure when compared to non-small cell lung cancer. Early stage small cell cancer can be treated by surgery in less than 10% of patients with this disease.
The category of non-small cell lung cancer is often divided into four separate cell types: Squamous cell, Adenocarcinoma, Large cell and Bronchioloalveolar cell.
Squamous cell cancer is most often found in the center of the lung or bronchial tree. This type of cancer is fairly slow growing and often follows a stepwise order, first to lymph nodes around the lung and then to other, more distant, organs in the body. It occurs more commonly in men and heavy smokers and is the cell type most likely to present with hemoptysis (coughing up blood).
Adenocarcinoma is more commonly found on the outer part of the lung or bronchial tree, occurs more frequently in women and non-smokers, and has a less predictable pattern of growth. Bronchioloalveolar cell cancer and large cell cancer are considered types of adenocarcinoma of the lung.
True bronchioloalveolar cell cancer grows along the existing lung makeup without invasion. It may present as a single nodule, multiple nodules, or as a diffuse infiltrate (haziness) resembling pneumonia on chest x-ray.
Large cell carcinoma often grows and spreads quickly, frequently with bizarre giant cells. Many large cell cancers will have neuroendocrine (interactions between the endocrine system and the nervous system) features.
Among the various cell types of non-small cell cancer, patient survival is based on the stage of the disease at presentation rather than on the cell type or degree to which the cells of the tumor are abnormal.
An estimated 172,570 new lung cancer cases will occur in 2005. Lung cancer ranks second to prostate and breast cancer in terms of new cancer cases in men and women respectively. With an estimated 163,510 lung cancer deaths in 2005, lung cancer is the number one cancer killer in men and women.
The annual rate of lung cancer in women increased from 6 cancers/100,000 women in 1960 to 30/100,000 in 1990. Since the 1950s there has been a 500% increase in the female lung cancer death rate. Lung cancer rates among women are expected to exceed those among men within the next 2 to 3 decades.
Smoking is the number one risk factor for lung cancer accounting for 80-90% of lung cancers. Studies show a genetic tendency demonstrated by a 30% increased risk of developing lung cancer among brothers, sisters, and children of lung cancer patients and an even higher risk if the relative who developed lung cancer was a woman. Patients with prior lung disease or smoking-related cancers are at increased risk for the development of primary lung cancer.
Second hand or environmental tobacco smoke has been linked with an increased risk for lung cancer. The strongest evidence comes from the much increased rate of lung cancer among lifetime non-smokers who are spouses of smokers. The risk is greatest among spouses of heavy smokers.
The most common signs and symptoms of lung cancer are cough, weight loss, shortness of breath, chest pain, increased sputum (phlegm) production and hemoptysis (coughing up blood). These symptoms develop slowly and are often thought of by the patient as a typical smoker's cough or a common cold. This, along with the tendency of doctors to think at first that the symptoms are due to bronchitis, pneumonia or flu, often leads to a delay between the start of symptoms and establishing the diagnosis of lung cancer.
Unfortunately, most lung cancers will be in advanced stages before causing any symptoms. Historically, more than 60% of patients diagnosed with lung cancer are incurable when a patient consults a doctor about symptoms.
Because of the high number of patients presenting with advanced disease, the 5-year survival rate in patients diagnosed with lung cancer is 15%. The overall 5-year survival rate of patients with localized lung cancer treated by surgical removal of the cancer with goal to cure is 60%.
This late presentation and poor overall survival has caused doctors to take steps to identify ways of reducing the number of lung cancer cases and identify lung cancer at an earlier more curable stage when it does occur.
The best way to prevent lung cancer is to not start smoking and avoid second-hand tobacco smoke. Cigarette smoking is the major cause of lung cancer. Historically, 80-90 % of lung cancers have occurred in current or former smokers.
Statewide tobacco control programs, which involve a mix of public education, print media campaigns, preventing children from getting tobacco, limiting advertising, creation of smoke-free environments, anti-smoking programs at work, health professional training on cessation techniques to offer patients, and school-based smoking prevention lessons have had the most success.
An additional step to avoid development of lung cancer is smoking cessation. The relative risk of developing lung cancer declines in former smokers to about twice that of those who never smoked after 20 years of not smoking. However, it remains high forever.
Currently in the United States about half of all those who have ever smoked are now former smokers. As more current smokers stop smoking, the lung cancer rates will go down and an increased number of lung cancer cases will occur in former smokers. Today, 50% of lung cancers develop in former smokers.
Unfortunately, most clinical trials for smoking cessation report only a 30-35% long-term success rate with motivated patients, drug intervention, and physician support. This has lead to the study of using drugs or supplements to reduce the risk of lung cancer in current or former smokers.
There are no agents that have proven to be effective for preventing lung cancer. There are good quality clinical studies demonstrating that giving beta carotene alone or in combination with retinol to smokers increase the number of cases of, and deaths from, lung cancer. Another study has shown that giving vitamin E to smokers has no effect on lung cancer rates. A national trial giving selenium to patients surgically treated for stage IA (earliest stage) lung cancer to prevent second lung cancers is ongoing.
In an attempt to reduce the death rate from lung cancer the National Cancer Institute sponsored three separate lung cancer screening trials in the 1970s. The Mayo Clinic, Johns Hopkins Medical Center, and Memorial Sloan Kettering Cancer Center each screened over 10,000 patients considered to be at risk for lung cancer. They used a combination of x-rays of the chest looking for lung nodules and sputum tests looking for cancer cells.
These studies demonstrated an advantage for screening in detecting earlier stage lung cancer and more lung cancers that could be treated with surgery. However, screening with chest x-ray and sputum tests did not decrease the death rate from lung cancer in the screened group when compared with the control group.
Currently, routine screening for lung cancer is not of proven benefit and is not recommended by the American Cancer Society. However, individuals who may be at increased risk for lung cancer should discuss with their family doctor whether screening tests are appropriate for them.
In the mid-1990's several centers in Japan and the United States looked at the use of spiral computed tomography (CT) of the chest as a screening tool for lung cancer. This new technology allows for a non-contrasted (no intravenous dye) single breath-hold (10 second) scan with radiation doses and costs similar to a standard chest x-ray.
The Early Lung Cancer Action Project performed a screening spiral CT scan of the chest on 1000 symptom-free volunteers considered at high risk for lung cancer. A total of 27 lung cancers were found in the screened group for a prevalence rate of 2.7%. 85% of the cancers were stage I (localized to the lung). 56% of the tumors were 1cm or less in size. This study along with the data from Japan has confirmed that spiral CT can detect early stage lung cancer.
The Society of Thoracic Radiology published a consensus statement on screening for lung cancer with helical computed tomography. The consensus statement does not recommend mass screening for lung cancer at this time, but strongly encourages appropriate subjects to participate in trials so that the true effectiveness of lung cancer screening with low-dose helical CT can be determined in the earliest possible time.
Members of the University of Cincinnati Thoracic Oncology Team are currently conducting a lung cancer screening trial using low-dose CT scans. We agree with the consensus statement published by the Society of Thoracic Radiology.
The best survival rates in non-small cell lung cancer are in patients treated with surgical resection for cure. The trend in other solid organ cancers, such as breast cancer, has been to perform smaller resections with radiation therapy and/or chemotherapy to reduce the complications & suffering seen with larger surgical resections. This has been done without affecting the cure rate in properly selected patients.
The Lung Cancer Study Group performed a randomized prospective (high quality) study comparing lobectomy to segmentectomy (partial lobe) as a treatment for early stage lung cancers. Patients treated with less than a lobectomy had an increased rate of recurring cancer and decreased long-term survival. The present recommendation is for all eligible patients to undergo at least a lobectomy for surgical treatment of non-small cell lung cancer. Segmentectomy may be offered to patients with severely reduced lung function that would not tolerate a lobectomy. These patients and the surgeon should understand that this is a compromise operation with increased recurrence and reduced survival.
Since smaller resections offer lower cure rates, thoracic surgeons have taken steps to reduce the complications and suffering from a lobectomy with an eye toward offering curative surgical resection to more patients with poor lung function and speeding the recovery of all patients. Several steps taken include pulmonary rehabilitation before surgery for patients with poor lung function, thoracic epidural analgesia for better pain control, and smaller incisions with less rib spreading. Along those lines a minimally invasive approach to early stage non-small cell lung cancers called Thoracoscopic Lobectomy is being offered at the University Hospital and selected centers around the country.
Thoracoscopic lobectomy involves removal of a lobe of the lung and the lymph nodes associated with that lobe using a videoscope, two small ports and a small (5-7cm) access thoracotomy thru which the lobe is removed without spreading the ribs. This approach allows for quicker recovery and causes less pain while still maintaining the same lung and lymph node removal with the intent for cure. It is currently limited to patients with small cancers localized to the lung.
Lung cancer remains a major public health problem as the number one cancer killer in both men and women. Doctors and the public need to push for tobacco control. Better methods for smoking cessation and ongoing research in chemoprevention should help in reducing lung cancer rates and deaths from lung cancer.
Current and future lung cancer screening trials will help identify patients with early stage disease and hopefully reduce the overall death rate from lung cancer in the screened groups.
The best cure rates are obtained in patients treated with complete surgical resection. The gold standard resection for cure remains a lobectomy. Unfortunately, at the present time only 1/3rd of patients present with disease treatable with surgical resection. Surgeons continue to refine operative techniques to offer this treatment to more lung cancer patients while reducing patient suffering.
In conclusion, the past has been bleak for lung cancer patients; the present is better but still disappointing, but the future is looking brighter every day.
You may want more information for yourself, your family, and your doctor. The following services are available to help you.
Provides accurate, up-to-date information on cancer to patients and their families, health professionals, and the general public. Information specialists translate the latest scientific information into understandable language and respond in English, Spanish, or on TTY equipment.
Toll-free: 1-800-4-CANCER (1-800-422-6237)
TTY (for deaf and hard of hearing callers): 1-800-332-8615
Lung cancer is the leading cancer killer in the United States, and the surest way to defeat it is to prevent it from ever happening. Contact your local American Lung Association® at 1-800-LUNGUSA to learn how you can help avoid lung cancer hazards. 1-800-LUNGUSA (1-800-586-4872). The American Lung Association's popular smoking cessation program is now available free online at http://www.ffsonline.org/.
NCI's Web site contains comprehensive information about cancer causes and prevention, screening and diagnosis, treatment and survivorship; clinical trials; statistics; funding, training, and employment opportunities; and the Institute and its programs.
This source of information is provided by the Centers for Disease Control and Prevention.
Chemotherapy - Chemotherapy refers to drugs that are used to kill microorganisms (bacteria, viruses, fungi) and cancer cells. Most commonly the term is used to refer to "cancer-fighting" drugs. Chemotherapy, as it refers to cancer treatment, is a generic term and includes many different drugs with a wide variety and severity of side effects. Generalizations regarding specific side effects and toxicities are difficult to make. Cancer chemotherapy kills or arrests the growth of cancer cells by targeting specific parts of the cell growth cycle. However, normal healthy cells share some of these pathways and thus are also injured or killed by chemotherapy. This is what causes most side effects from chemotherapy. Chemotherapy usually targets rapidly dividing cells. Some normal cells -- including blood cells, hair, and cells lining the gastrointestinal tract -- are also rapidly dividing and thus these are the normal cells most likely to be damaged. Newer cancer therapies, some of which have already been approved by the FDA, are more specifically targeted at growth pathways that are only found in cancer cells. Thus, these drugs may be more effective while also being less toxic.
Neoadjuvant Chemotherapy - Chemotherapy given alone or with radiation therapy before surgical resection of a cancer.
Adjuvant Chemotherapy - Chemotherapy given alone or with radiation after surgical resection.
Lobectomy - The right lung has three lobes, and the left lung has two lobes. A lobectomy removes an entire lobe of lung containing the cancer (tumor).
Bilobectomy - A lobectomy removing two of the five lobes
Local Control - Eradication of cancer from a specific area (by surgical resection or radiation).
Local Therapy - Treatment done to treat only specific areas of the body. These treatments include surgical resection (removal) of a cancer and radiation therapy.
Mediastinoscopy - A procedure that can help show whether the cancer has spread to the lymph nodes in the chest. Using a lighted viewing instrument, called a scope, the doctor examines the center of the chest (mediastinum) and nearby lymph nodes. In mediastinoscopy, the scope is inserted through a small incision in the neck; in mediastinotomy, the incision is made in the chest. In either procedure, the scope is also used to remove a tissue sample.
Pneumonectomy - Removal of the entire right or left lung. This is typically done for larger cancers located in the center (hilum) of the lung.
Radiation Therapy - Radiotherapy - A treatment method that uses high-energy, ionizing radiation (e.g., gamma rays) to kill cancer cells. Ionizing radiation is produced by a number of radioactive substances, such as cobalt (60Co), radium (228Ra), iodine (131I), radon (221Rn), cesium (137Cs), phosphorus (32P), gold (198Au), iridium (192Ir), and yttrium (90Y). Radiotherapy may be applied to shrink a tumor that is later removed by surgery, to relieve symptoms, or to destroy malignant cells in a tumor that cannot be removed surgically.
Staging of Non-Small Cell and Small Cell Lung Cancer - The stage of a cancer is based on the size of the cancer and how far it has spread. In early stages, lung cancer may be confined to one small area of the lung. In later stages, it may spread within the lungs or through the lymph nodes to other parts of the body.
Non-small cell lung cancer - is divided into four stages, I-IV. Most patients with stage I and II non-small cell tumors and some patients with stage III tumors can undergo surgery with the goal of cure. Stage IV denotes cancer that has spread to other sites in the body (most often bone, brain, or liver) and is, in most cases, not curable.
Small cell lung cancer - is divided into "limited stage" (generally cancer confined to the chest) and "extensive stage" (cancer that has spread outside the chest).
Systemic Therapy - Treatment that treats the whole body system. These treatments include chemotherapy and cancer vaccines.
Thoracoscopy - Video-assisted thoracic surgery (VATS), also called thoracoscopy, may be done as an independent procedure, or before a thoracotomy. This procedure involves inserting a long, thin, fiber-optic scope with a camera attached and instruments into the chest through small incisions made between the ribs. A VATS procedure may be used to confirm the diagnosis of lung cancer or other chest diseases. It also can be used to biopsy lymph nodes in the center part of the chest (mediastinum). Recent advances have allowed surgeons to apply the VATS approach to lobectomy for local control in small stage I lung cancers. Many smaller chest procedures may be performed using VATS, rather than a standard thoracotomy.
Thoracotomy - A standard chest incision, typically to enter the chest along the side under the arm going between the ribs. Surgery using this approach avoids areas in the chest containing the heart and the spinal cord.
The information in this article is based on "LUNG CANCER: Battling the Number 1 Cancer Killer," presented on October 7, 2003 at the University of Cincinnati Mini Medical College, and was adapted for use on NetWellness with permission, 2004.
Last Reviewed: Dec 06, 2006
John Howington, MD
College of Medicine
University of Cincinnati