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Lung cancer is the leading cancer-related cause of death worldwide. About 85% of all lung cancer cases are related to cigarette smoking. Common symptoms include: cough, chest discomfort or pain, weight loss and hemoptysis, the coughing up of blood from the respiratory tract. However, many patients present with advanced, metastatic disease without any clinical symptoms. Treatment options for lung cancer include surgery, chemotherapy, radiation therapy or a combination of these treatments. The prognosis for lung cancer patients is relatively poor, with only 15% of patients surviving for more than 5 years. Moreover, less than 1% of patients presenting with stage 4 lung cancer survive for more than 5 years. Therefore it is very important to improve the treatment options available for stage 4 adenocarcinoma lung cancer.
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Lung adenocarcinoma is a form of non-small cell lung cancer. It is the most common form of lung cancer, with approximately half of all lung cancers being diagnosed as an adenocarcinoma. Women are more commonly diagnosed with this form of cancer than men. While smoking elevates the risk of developing lung cancer, adenocarcinomas are often found in the non-smoking population. Adenocarcinomas generally begin in the outer parts of the lung. They are usually present within the lung for long periods of time before it is diagnosed. Stage 4 adenocarcinoma lung cancer is characterized by the spreading of the cancer to a distant tissue and a poor prognosis. It is denoted by the presence of metastatic disease with the most common sites metastasis being the liver, bones, adrenal, brain and contralateral lung.
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Cancer types are usual classified via histological techniques. However, Lung adenocarcinomas tend to be histologically heterogeneous or have characteristics similar to that of a variety of cancer subtypes. Due to this high percentage of heterogeneity, the International Association for the Study of Lung Cancer (IASLC) now classifies adenocarcinomas under a group of diagnostic subtypes. Some stage 4 adenocarcinoma lung cancers include:
- Well-differentiated fetal adenocarcinoma (rare subtype that exhibits cell characteristics that resemble fetal lung tissue)
- Mucinous (colloid) adenocarcinoma (mucus-producing intrapulmonary neoplasm)
- Mucinous cystadenocarcinoma (very rare mucus-producing neoplasm arising from the uncontrolled growth of transformed lung epithelial cells)
- Signet ring adenocarcinoma (lung epithelial malignancy characterized by the histological appearance of signet ring cells)
- Clear cell adenocarcinoma (a large cell tumor forming nests, clusters or sheets of cells)
This heterogeneity of lung adenocarcinomas makes advancements in histological subtype and characterization essential to ensure that all lung cancer patients are effectively treated.
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The first step in diagnosing a stage 4 adenocarcinoma lung cancer is a clear and well-directed interview by a healthcare professional. The interview should focus on the patient’s symptoms, medical and surgical history, family history and smoking status (non-smoker, former smoker or smoker). It could also be important to get information about the patient’s: work history, lifestyle, overall health and current and past medication use.
In general stage 4 adenocarcinoma lung cancer patients present with severe respiratory problems such as hemoptysis. A chest X-ray is the first diagnostic technique used to help identify the source of the respiratory problem. X-rays can identify many along abnormalities such as small nodules or large masses. However, not all of these abnormalities are cancerous. To help identify certain lung cancers, more advanced imaging techniques such as CT scans and MRIs can be used. These techniques provide the physician with a greater detailed three dimensional image of the lung. Moreover, CT scans or MRIs are generally chosen over X-rays in patients presenting with more severe symptoms.
If the above imaging diagnostic techniques identify a possible cancerous lesion, the next step is a tumor biopsy, the collection of a small amount of tissue to send to a pathologist for characterization. There are many biopsy techniques that can be used. These include:
- Sputum testing – the analysis of the thick mucus produced during a cough
- Bronchoscopy – insertion of a small camera and incision knife via the airway
- Needle biopsy – insertion of a needle through the chest wall and into the tumor
- Thoracentesis – Removal and sampling of the fluid with the pleural cavity surrounding the lung
- Thoracotomy – Surgically opening the chest cavity to obtain a tumor biopsy
- Mediastinoscopy – similar to a bronchoscopy but it is performed to examine the extent of cancer spreading to other areas of the chest cavity
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Treatment and Cancer Stage
There are specific combinations of treatments that are recommended for adenocarcinoma lung cancer. These options depend on the stage of the cancer and the patient's overall health.
- Stages I and II. Most patients in these stages typically undergo tumor removal surgery as their primary treatment. If surgery is not an option, radiation therapy with or without chemotherapy is often recommended.
- Stages IIIA and IIIB. The primary treatment option for patients in these stages is chest radiation treatment combined with chemotherapy. While tumor removal surgery may be recommended to patients with very limited stage IIIA disease, surgery usually is not recommended for stage IIIB tumors.
- Stage IV. Surgery is never an option for cancers of this stage. Chemotherapy is the main treatment of stage IV disease. Meanwhile, radiation therapy may be recommended as well, but is usually targeted to areas that cause the patient pain or other problems.
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Treatment Options for Stage 4 Adenocarcinoma Lung Cancer
A large variety of international guidelines recommend chemotherapy for the primary treatment of stage 4 adenocarcinoma lung cancer. It is recommended that platinum-based chemotherapies be used in patients that are considered to be healthy and in overall good shape. The reason for this is that these therapies are most effective, yet tend to be the most toxic also. If the patient presents in a weak and in a relatively poor health, other chemotherapies or even radiotherapy should be considered. Since this stage of lung cancer is metastatic, it is important to note that lung surgery is generally not considered a viable treatment option and is definitely not a cure as the cancer is now present in distant sites.
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Merck Manual - http://www.merck.com/mmpe/sec05/ch062/ch062b.html
eMedicine Health - http://www.emedicinehealth.com/lung_cancer/page5_em.htm#Exams%20and%20Tests
National Cancer Institute - http://www.cancer.gov/cancertopics/pdq/treatment/non-small-cell-lung/HealthProfessional/page5
Mayo Clinic - http://www.mayoclinic.org/lung-cancer/treatment.html
Chemotherapeutic Management of Stage IV Non-small Cell Lung Cancer. Socinski et al. 2003.