The abnormal growth of cells that begins in one or both lungs, generally in the cells lining the air passages is known as lung cancer. These abnormal cells do not grow into a healthy lung tissue and as a result of this, they divide for forming tumors. These innumerable and large tumors weaken the lungs and due to this they cannot provide the bloodstream with oxygen.
Types of Lung Cancer
Lung cancers are broadly classified into two types: small cell lung cancers (SCLC) and non-small cell lung cancers (NSCLC). SCLC comprises about 20% of lung cancers and are the most aggressive and rapidly growing of all lung cancers. NSCLC are the most common lung cancers, accounting for about 80% of all lung cancers. NSCLC can be divided into three main types that are named based upon the type of cells found in the tumor: Adenocarcinomas, Squamous cell carcinomas, large cell carcinomas and mixtures of different types of NSCLC are also seen.
- Difficulty in swallowing
- Raspy, chronic or hacking coughing sometimes with blood-streaked mucus
- Weakness and pain in the hand, shoulder or arm
- Frequent respiratory infections such as pneumonia or bronchitis
- Weakness, severe headaches, body pain, fatigue, intermittent fever, loss of appetite and weight
- Continuous increase in shortness of breath, wheezing and also constant chest pain
- Face and neck swelling
Oncologists use a wide range of diagnostic procedures which include:
- History and physical examination, and imaging with chest X-ray and CT scan or MRI.
- Positron emission tomography (PET) scanning is a specialized imaging technique that uses short-lived radioactive drugs to produce three-dimensional colored images of those substances in the tissues within the body, in a growing tumor.
- Bone scans are used to create images of bones on a computer screen or on film.
- Sputum cytology: The diagnosis of lung cancer requires confirmation of malignant cells by a pathologist. The simplest method to establish the diagnosis is the examination of sputum under a microscope.
- Bronchoscopy: Examination of the airways through a probe inserted through the nose or mouth may reveal areas of tumor that can be sampled (biopsied) for diagnosis by a pathologist.
- Needle biopsy: Fine needle aspiration (FNA) through the skin, most commonly performed with radiological imaging for guidance, may be useful in retrieving cells for diagnosis from tumor nodules in the lungs.
- Thoracentesis: Sometimes lung cancers lead to an accumulation of fluid in the space between the lungs and chest wall (called a pleural effusion). Aspiration of a sample of this fluid with a thin needle (thoracentesis) may reveal the cancer cells and establish diagnosis.
Treatment for lung cancer can involve surgical removal of the cancer, chemotherapy, or radiation therapy, as well as combinations of these treatments. The decision about which treatments will be appropriate for a given individual must take into account the location and extent of the tumor as well as the overall health status of the patient.
As with other cancers, therapy may be prescribed that is intended to be curative (removal or eradication of a cancer) or palliative (measures that are unable to cure a cancer but can reduce pain and suffering). More than one type of therapy may be prescribed.
Surgical removal of the tumor is generally performed for limited-stage (stage I or sometimes stage II) NSCLC and is the treatment of choice for cancer that has not spread beyond the lung. About 10%-35% of lung cancers can be removed surgically, but removal does not always result in a cure, since the tumors may already have spread and can recur at a later time.
The surgical procedure chosen depends upon the size and location of the tumor. Surgeons must open the chest wall and may perform a wedge resection of the lung (removal of a portion of one lobe), a lobectomy (removal of one lobe), or a pneumonectomy (removal of an entire lung). Sometimes lymph nodes in the region of the lungs also are removed (lymphadenectomy). Surgery for lung cancer is a major surgical procedure that requires general anesthesia, hospitalization, and follow-up care for weeks to months.
Radiation therapy may be employed as a treatment for both NSCLC and SCLC. Radiation therapy uses high-energy X-rays or other types of radiation to kill dividing cancer cells. Radiation therapy may be given as curative therapy, palliative therapy (using lower doses of radiation than with curative therapy), or as adjuvant therapy in combination with surgery or chemotherapy.
Radiation therapy generally only shrinks a tumor or limits its growth when given as a sole therapy, yet in 10%-15% of people it leads to long-term remission and palliation of the cancer. Combining radiation therapy with chemotherapy can further prolong survival when chemotherapy is administered. External radiation therapy can generally be carried out on an outpatient basis, while internal radiation therapy requires a brief hospitalization.
Both NSCLC and SCLC may be treated with chemotherapy. Chemotherapy refers to the administration of drugs that stop the growth of cancer cells by killing them or preventing them from dividing. Chemotherapy may be given alone, as an adjuvant to surgical therapy, or in combination with radiotherapy. While a number of chemotherapeutic drugs have been developed, the class of drugs known as the platinum-based drugs have been the most effective in treatment of lung cancers.
Chemotherapy is the treatment of choice for most SCLC, since these tumors are generally widespread in the body when they are diagnosed. Chemotherapy alone is not particularly effective in treating NSCLC, but when NSCLC has metastasized; it can prolong survival in many cases.
Targeted therapy drugs more specifically target cancer cells, resulting in less damage to normal cells than general chemotherapeutic agents. Erlotinib and gefitinib target a protein called the epidermal growth factor receptor (EGFR) that is important in promoting the division of cells. This protein is found at abnormally high levels on the surface of some types of cancer cells, including many cases of non-small cell lung cancer.
Other attempts at targeted therapy include drugs known as antiangiogenesis drugs, which block the development of new blood vessels within a cancer. Without adequate blood vessels to supply oxygen-carrying blood, the cancer cells will die. The antiangiogenic drug bevacizumab (Avastin) has also been found to prolong survival in advanced lung cancer when it is added to the standard chemotherapy regimen.