Lung cancer, as any other cancer, is the result of cells which grow uncontrollably. A lump or tumor, known as the primary tumor, can grow locally or spread to other places in the body. This spread is known as metastasis. Lung cancer is the most common form of cancer found in the United States and the UK. The primary cause of lung cancer is tobacco smoke and although non-smokers can get lung cancer, the risk is 10 times greater for smokers.
Because symptoms of lung cancer do not often show up until the disease is in an advanced state, finding this particular type of cancer early is difficult. Symptoms of lung cancer include a chronic cough, worsening breathlessness, weight loss, fatigue and persistent pain in the chest or elsewhere if the cancer has spread. These symptoms can be due to an original tumor or secondary tumors in the body. One of the hallmark signs of lung cancer is when individuals cough up blood. Unfortunately, although it may be an early sign of cancer, this symptom is also a sign of later stages of cancer.
At this time the five-year survival rate for people with lung cancer is approximately 60% when there is no evidence in the lymph nodes at the time of surgery. In contrast, when the cancer has spread to the lymph nodes, the five-year survival rate is only 14%. This emphasizes the need for early diagnosis of lung cancer to improve the survival rate of the sufferer.
Interestingly, many early diagnoses of lung cancer are found incidentally. This means they are found as a result of testing being done for an unrelated medical condition. If the patient has pneumonia or another lung condition which requires a chest x-ray, bronchoscopy or sputum collection these test results can reveal early stages of lung cancer.
Doctors will use a wide range of procedures and tests to diagnose lung cancer. Patients who are at higher risk for the disease should approach their physician and seek medical advice if they believe they have any of the symptoms of lung cancer. Early treatment will increase the likelihood of extending life for several years. Physicians will start with a thorough history and physical examination looking for signs of difficulty with breathing, infection in the lungs or a bluish color to the skin and mucous membranes which indicates that there is not enough oxygen in the blood.
An initial chest x-ray will be done to look for any suspicious areas in the lungs but these are unable to detect or determine if these areas are in fact, cancer. Particularly calcified nodules in the lungs or other benign tumors may be identified on chest x-ray. Further testing is necessary to more fully identify what is found on the initial x-rays.
Included in diagnostic studies will be sputum cytology in which the sputum, or production of mucus from the lungs, of an individual is examined under a microscope. This can allow visualization of tumor cells for diagnosis and is the most risk free and inexpensive tissue procedure done. Another test that can be done is the bronchoscopy which examines the airways of the lungs. This test will enable the physician to visualize the lungs and if the tumor is seen can be adequately sampled or biopsied.
If something suspicious shows up on a chest x-ray the physician will order further testing. These tests can include a CT scan performed on the chest, abdomen and brain to evaluate the primary tumor and look for any signs of metastasis. An MRI scan may be appropriate when more detail about a tumor location is necessary and a PET scan may be ordered when the physician wants to measure metabolic activity and function of the tumor. This information will give the physician an idea of the activity level of the cells since tumors that are rapidly growing also have a faster metabolism and give off more heat.
If the physician believes there may be metastasis, then a bone scan will be ordered to determine to which bones the tumor has spread. In other cases a fine needle aspiration or needle biopsy may be done through the skin and using x-ray imaging for guidance. Physicians may order this for retrieval of tumor cells from the lungs in order to more accurately diagnose the cell type if the tumor is not accessible through bronchoscopy.
The position will also order routine blood tests which, although will not diagnose lung cancer, will be able to reveal biochemical or metabolic abnormalities that accompany the growth of cancer in the body.
In a study published in the New England Journal of Medicine in October 2006, researchers found that the use of low-dose CT scan performed every seven to 18 months on high risk patients were able to find more stage one lung cancers and increased five-year survival rates to up to 92%. Researchers in this study believe that further investigation was necessary but also that in high-risk populations low dose spiral CT scan done on an annual basis would improve survival rates for individuals found with lung cancer. (1)
Because the early diagnosis of lung cancer is difficult, it is important for individuals who recognize they have high-risk behaviors, such as smoking, to be evaluated and screened by their physician on an annual basis. Treatment of lung cancer is complex and not often successful greater than five years. By finding lung cancer in clinical stage one individuals have a greater chance of surviving for five years and longer.