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For Patient - Lung Cancer Symptoms |
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Cancer |
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CANCER : Lung
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Lung cancer is the leading cause of cancer deaths in both women and men throughout the world. Lung cancer has surpassed breast cancer as the leading cause of cancer deaths in women.
Most lung tumors are malignant. This means that they invade and destroy the healthy tissues around them and can spread throughout the body. The tumors can also spread to nearby lymph nodes or through the bloodstream to other organs. This process is called metastasis. When lung cancer metastasizes, the tumor in the lung is called the primary tumor, and the tumors in other parts of the body are called secondary tumors or metastatic tumors.
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Some lung tumors are metastatic from cancers elsewhere in the body. The lungs are a common site for metastasis. If this is the case, the cancer is not considered to be lung cancer. For example, if kidney cancer spreads to the lungs, it is metastatic kidney cancer (a secondary cancer) in the lung and is not called lung cancer. |
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Types |
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Lung cancers are usually divided into two main groups that account for about 95% of all cases. The two main types of lung cancer are characterized by the cell size of the tumor when viewed under the microscope. They are called small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). NSCLC includes several subtypes of tumors.
SCLCs are less common, but they grow more quickly and are more likely to metastasize than NSCLCs. Often, SCLCs have already spread to other parts of the body when the cancer is diagnosed.
About 5% of lung cancers are of rare cell types, including carcinoid tumor, lymphoma and others.
- Adenocarcinoma (an NSCLC) is the most common type of lung cancer, making up 30%-40% of all cases. A subtype of adenocarcinoma is called bronchoalveolar cell carcinoma, which creates a pneumonia-like appearance on chest x-rays.
- Squamous cell carcinoma (an NSCLC) is the second most common type of lung cancer, making up about 30% of all lung cancers.
- Large cell cancer (another NSCLC) makes up 10% of all cases.
- SCLC makes up 20% of all cases.
- Carcinoid tumors account for 1% of all cases.
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Causes |
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Cigarette smoking is the most important cause of lung cancer. Research as far back as the 1950s clearly established this relationship.
- Cigarette smoke contains more than 4,000 chemicals, many of which have been identified as causing cancer.
- A person who smokes more than one pack of cigarettes per day has a risk of developing lung cancer 20-25 times greater than someone who has never smoked.
- Once a person quits smoking, his or her risk for lung cancer gradually decreases. About 15 years after quitting, the risk for lung cancer decreases to the level of someone who never smoked.
- Cigar and pipe smoking increases the risk of lung cancer but not as much as smoking cigarettes.
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About 90% of lung cancers arise due to tobacco use. The risk of developing lung cancer is related to the following factors:
- the number of cigarettes smoked,
- the age at which a person started smoking, and
- how long a person has smoked (or had smoked before quitting).
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Other causes of lung cancer include the following:
- Passive smoking, or secondhand smoke, presents another risk for lung cancer.
Air pollution from motor vehicles, factories, and other sources probably increase the risk for lung cancer, and many experts believe that prolonged exposure to polluted air is similar to prolonged exposure to passive smoking in terms of risk for developing lung cancer.
- Asbestos exposure increases the risk of lung cancer by nine times. A combination of asbestos exposure and cigarette smoking raises the risk to as much as 50 times. Another cancer known as Mesothelioma (a type of cancer of the pleura or of the lining of the abdominal cavity called the peritoneum) is also strongly associated with exposure to asbestos.
- Lung diseases, such as tuberculosis (TB) and chronic obstructive airway disease (COPD), also create a risk for lung cancer. A person with COPD has a four to six times greater risk of lung cancer even when the effect of cigarette smoking is excluded.
- Radon exposure poses another risk.
- Radon is a by-product of naturally occurring radium, which is a product of uranium.
- Radon is present in indoor and outdoor air.
- The risk for lung cancer increases with significant long-term exposure to radon, although no one knows the exact risk. As with asbestos exposure, smoking greatly increases the risk of lung cancer with radon exposure.
- Certain occupations where exposure to arsenic, chromium, nickel, aromatic hydrocarbons, and ethers occurs may increase the risk of lung cancer.
A person who has had lung cancer is more likely to develop a second lung cancer than the average person is to develop a first lung cancer.
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Diagnosis |
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Up to one-fourth of all people with lung cancer may have no symptoms when the cancer is diagnosed. These cancers usually are identified incidentally when a chest x-ray is performed for another reason.
The majority of people, however, develop symptoms.
The symptoms are due to direct effects of the primary tumor, to effects of metastatic tumors in other parts of the body, or to disturbances of hormones, blood, or other systems caused by the cancer. Besides clinical examination, many diagnostic procedure are available:
- Chest x-ray may or may not show abnormality.
- CT / MRI are better than x-ray.
Sputum testing: The sputum may reveal malignant cells (cytological review). However, this is not very reliable, if negative.
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| Bronchoscopy: |
This is an endoscopic test, meaning that a thin, flexible, lighted tube with a tiny camera on the end is used to view organs inside the body. The physician operating the bronchoscope can look for tumors and collect samples of any suspected tumors. Bronchoscopy can usually be used to determine the extent of the tumor. |
| Needle biopsy: |
If a tumor is on the periphery of the lung, it usually cannot be seen with bronchoscopy. Instead, a biopsy is taken through a needle inserted through the chest wall and into the tumor. |
| Thoracentesis: |
Lung cancers, both primary and metastatic, can cause fluid to collect surrounding the lung. This fluid is called a pleural effusion. Sampling this fluid can confirm the presence of cancer in the lungs. The fluid sample is removed by a needle in a procedure similar to needle biopsy.
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| Thoracotomy: |
Sometimes a lung cancer tumor cannot be reached by bronchoscopy or needle procedures. In these cases, the only way to obtain a biopsy is by performing an operation. The chest is opened (thoracotomy), and as much of the tumor as possible is removed surgically. The removed tumor is then examined microscopically. |
| Mediastinoscopy: |
This is another endoscopic procedure. It is performed to determine the extent that the cancer has spread into the area of the chest between the lungs (the mediastinum). A small incision is made into the lower part of the neck, above the sternum or sometimes the incision is made in the chest. A mediastinoscope is inserted and samples of the lymph nodes are taken to evaluate for cancer cells. |
| PET/CT Scan: |
Nowadays F-18 FDG PET CT scan is routinely performed for diagnosis, staging and monitoring therapy of the lung cancer. This is a non-invasive test. |
| Bone scan: |
A bone scan is performed to rule out spread of cancer to the bones for staging as well as for follow-up. |
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Treatment |
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Treatment decisions in lung cancer depend on the type ( SCLC or NSCLC ) and tumor staging. A person's general physical condition (the ability to withstand treatment procedures) is also taken into account.
The most widely used therapies for lung cancer are surgery, chemotherapy, and radiation therapy. Your treating physician would be the best person to discuss various options with you. |
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Follow-up |
Many lung cancers come back after treatment. Regular testing should be performed so that any recurrence can be identified as early as possible. |
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Solitary Pulmonary Nodule |
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The solitary pulmonary nodule (SPN) is a commonly encountered clinical entity in both plain film radiography as well as computed tomography (CT). An understated aspect of the evaluation of a solitary pulmonary nodule is establishing that the opacity seen on the CXR is indeed a true intra-pulmonary nodule. Once this has been established, the demographic features, including the patient’s clinical history, gender, age, smoking history, industrial or environmental exposure and prior malignancy all play an important part in the work-up of the SPN. These are independent of the imaging characteristics of the pulmonary nodule.
The goal of evaluating the solitary pulmonary nodule is to establish benignity or malignancy.
Beside thin section computed tomography, PET-CT and even biopsy may be required. |
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Definition |
A solitary pulmonary nodule is defined as a single, round, fairly well marginated intra-parenchymal opacity less than 3 cm in diameter. The arbitrary size limitation is based on the fact that larger lesions (termed masses) are more often malignant than those smaller than 3cm.
Differential Diagnosis
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| Mimics and pseudo lesions seen on the frontal CXR include bony islands, healing rib fractures, overlapping vascular shadows and thoracic spinal osteophytes. Many so called SPNs turn out to be multiple lesions on CT. Most benign SPNs are granulomas, hamartomas or intrapulmonary lymph nodes. Most malignant SPNs are bronchogenic carcinomas. |
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Chracteristics Of The SPN |
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| Size |
Larger lesions tend to be malignant. Although 80 % of benign lesions are less than 2cm, small size is not a reliable indicator of benignity because 15% of malignant lesions are less than 1cm at diagnosis and 42% are less than 2cm. With the advent of low dose CT for routine screening, more small lesions would be picked up. |
| Density and internal characteristics |
Calcification
- Benign patterns of calcifications include central, solid, laminated, diffuse or popcorn.
- Not all calcified lesions are benign as these may be engulfed by a scar carcinoma
- Many “non-calcified” SPNs on plain radiographs have calcifications on thin section CT.
- The absence of calcium is of little diagnostic value because 40-60% of benign nodules and two-thirds of carcinoid tumours do not contain appreciable calcium. Also, 5% of malignant tumours may have calcifications.
Cavitation
- Both malignant and benign lesions may cavitate.
- Malignant lesions tend to have thick irregular walls measuring 15mm and more.
- Benign lesions tend to have thinner walls, often measuring less than 5mm. These include infectious granulomas, Wegener granulomatosis, abscesses and pulmonary infarcts.
Air-brochograms
- The presence of air-bronchograms is not a characteristic of malignancy except for bronchioalveolar carcinoma and lymphoma.
- Air-bronchograms can also be seen in benign lesions such as organizing pneumonia , pulmonary infarcts and sarcoidosis.
Tubular or branching lesion
- Would suggest benignity such as a mucocoele which would be readily apparent on thin section CT.
Fat
- The identification of fat is an indication of benignity and is frequently (up to 50%) found in a pulmonary hamartoma, the third most common cause of SPN.
CT contrast enhancement
- Requires pre and post-contrast acquisitions and is less accurate in larger lesions (more than 2cm) because of necrosis. Enhancement of less than 15HU is almost diagnostic of a benign lesion. Both inflammatory and malignant lesions enhance and is therefore of limited value.
Vascularity
- Malignant lesions may have enlarged supplying arteries or drainage veins. However, a tangle of vessels is in keeping with a diagnosis of an arterio-venous malformation.
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| Margins |
- A smooth , well-defined margin indicates benignity but 21% are malignant.
- Lobulated margins indicate uneven growth and suggest malignancy but 25% of hamartomas are lobulated.
- Spiculated margins result from cicatrization of the interstitium and is a sign of malignancy. Benign lesions with speculated margins include lipoid pneumonia, organizing pneumonia, tuberculoma and progressive massive fibrosis.
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| Growth |
- The rate of growth can be helpful.
- The lack of growth over at least a 2-year period is a reliable indicator of benignity.
- Very rapid growth on the other hand indicates an inflammatory or infective cause.
- Doubling time is defined as a 26% increase in diameter.
- Computed tomography software can help calculate nodule volume.
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PET-CT |
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Some indeterminate nodules will require further evaluation. The FDG uptake is measured semi-quantitatively and can be helpful in some cases. It is useful in distinguishing tumour and post-obstructive atelectasis. One of its principal advantages lies in mediastinal staging with a high negative predictive value of more than 90%, negating mediastinoscopy and biospsy. Detecting unsuspected metastases and recurrence are other advantages of PET-CT. Its main disadvantage is its high cost. |
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Pathologic Diagnosis Of SPNs |
Transthoracic needle biopsy |
Image-guided transthoracic needle biopsy is a semi-invasive procedure of choice for definite characterization of peripheral SPNs. It is more sensitive for malignant lesions with a positive yield of more than 90%. Biopsy for benign lesions often yield a nonspecific inflammatory return. Some benign lesions resist biopsy attempts because they too sclerotic. |
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Bronchoscopy
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Is preferred for central lesions. Diagnostic yield from brushings, washings and endo or transbronchial needle aspirates vary widely with size and location of lesion and experience of bronchoscopist.
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Video-assisted thoracoscopic Surgery (VATS)
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Performed by a surgeon under general anesthesia and single lung ventilation. It is less invasive than
thoracotomy and can be therapeutic for small lesions. |
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A proposed DIAGNOSTIC ALGORITHM for the approach to an SPN is detailed below: |
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| Click on the chart above for enlargement. |
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