Lung Cancer: A Overview
Lung cancer is cancer that forms in lung tissues, usually in the cells lining the air passages. It is the leading cause of cancer death in both men and women worldwide.
Smokers are at the highest risk of lung cancer, though lung cancer may also occur in non-smokers.
What causes lung cancer?
There can be various causes of lung cancer. Some of them are mentioned as follows:
The exact cause of breast cancer remains unknown, yet certain factors are linked to the chance of getting the disease such as gender, age, weight, genetic risk factors, your family history & personal history, Exposure to breast radiation early in life, the age of onset of menstruation and menopause, Alcohol and tobacco intake etc.
2) Exposure to radon gas:
Radon gas is a known cause of lung cancer. Radon is a naturally occurring radioactive gas that results from the natural breakdown of uranium in soil, rocks and water. It is invisible, odourless; however, can be detected with simple test kits. Radon decays and forms products which emit a type of ionizing radiation. Radon gas can travel through soil and enter homes through cracks/gaps in foundation, pipes, drains, etc.
3) Exposure to asbestos:
Asbestos fibres are silicate fibres that can persist for a lifetime in lung tissue following exposure to asbestos. Exposure to asbestos usually occurs at the workplace as asbestos was used in the past for thermal and acoustic insulation materials. Other than lung cancer, a type of cancer of the pleura or the lining of the abdominal cavity, i.e. peritoneum called mesothelioma is also associated with asbestos exposure.
4) Exposure to other cancer-causing agents (carcinogens):
Other carcinogens at the workplace which can increase risk of lung cancer include radioactive ores such as uranium; inhaled chemicals such as arsenic, beryllium, cadmium, silica, vinyl chloride, nickel compounds, chromium compounds, coal products, mustard gas, and chloromethyl ethers; diesel exhaust, etc.
5) Family history of lung cancer, inherited genetic mutations:
People with a parent, sibling or child with lung cancer have an increased risk of the disease.
6) Previous history of lung cancer:
The person who has survived lung cancer has a greater risk than the general population of developing second lung cancer.
7) Air pollution:
Prolonged exposure to polluted air from vehicles, industry, and power plants, can increase the chance of developing lung cancer.
8) Previous radiation therapy:
Previous radiation therapy to the chest for another type of cancer increases the risk of developing lung cancer.
LUNG CANCER PREVENTION:
All lung cancers can not be prevented. However, some measures can be taken to prevent the risk of lung cancer. They include:
- Non-smokers should avoid all forms of smoke- pipe, cigar, tobacco; and also passive smoking.
Avoid radon exposure.
Avoid or limit exposure to cancer-causing agents/carcinogens.
Maintaining a healthy diet.
TYPES OF LUNG CANCER:
Lung cancer can be divided into two major types depending on the microscopic appearance of the tumour cells. This helps in deciding the line of treatment. The two types include:
1) Small cell lung cancer (SCLC): This type of lung cancer is usually seen in heavy smokers. It is the most aggressive and rapidly growing of all types. It is less common and comprises 10 to 15% of all lung cancers. It is sometimes also called oat cell cancer. SCLC has a rapid metastasis and spreads to many sites within the body and is often diagnosed after the extensive spread.
2) Non-small cell lung cancer (NSCLC): This type of lung cancer is most common and comprises about 80 to 85% of all lung cancers. Non-small cell lung cancers include squamous cell carcinoma, adenocarcinoma and large cell carcinoma. NSCLC has three main types divided according to the type of cells found in the tumor. They are as follows:
This type of lung cancer is mainly seen in current or former smokers, however, is also the most common type seen in non-smokers. It is more common in women than men, and more likely occurs in younger people. Adenocarcinoma arises in the outer, peripheral parts of the lung.
Adenocarcinoma in situ (previously called bronchioloalveolar carcinoma) is a subtype of adenocarcinoma which frequently develops at multiple sites in the lungs and spreads along the preexisting alveolar walls. It may also look like pneumonia on a chest X-ray. It is more common in women. People with adenocarcinoma in situ tend to have a better prognosis than those with other types of lung cancer.
ii) Squamous cell carcinoma:
Squamous cell carcinomas start in squamous cells, which are flat cells lining the inside of the airways in the lungs. They account for about 25% to 30% of all lung cancer cases. They are mostly found in be found in the central part of the lungs.
iii) Large cell (undifferentiated) carcinoma:
Large cell carcinomas are the least common type of NSCLCs and account for 10 to 15% of all lung cancers. It can appear in any part of the lung and tends to grow and spread quickly, which makes it harder to treat.
iv) Other subtypes:
Few other subtypes of NSCLC, such as adenosquamous carcinoma and sarcomatoid carcinoma, are much less common.
3) Other types of lung cancers:
They are much less common than NSCLC and SCLC and comprise only 5%-10% of lung cancers.
i) Lung carcinoid tumors/ Bronchial carcinoids:
They account for up to 5% of lung cancers and occur mostly in persons under age 40. Carcinoids generally have slow growth and spread more slowly than bronchogenic cancers. Many times, they are detected early enough to be surgically removed.
ii) Other types like adenoid cystic carcinomas, lymphomas, and sarcomas, as well as benign lung tumors such as hamartomas, are rare.
SYMPTOMS OF LUNG CANCER:
Lung cancer usually doesn’t cause signs and symptoms in its early stages. Signs and symptoms typically appear when the disease is advanced. Symptoms of non-small cell lung cancer and small cell lung cancer are basically the same. They may include:
Lingering or worsening cough.
Coughing up phlegm or blood.
- Chest pain that worsens on breathing deeply, laughing, or coughing.
Shortness of breath.
- Weakness and fatigue.
- Loss of appetite and weight loss.
- Bone pain.
- Recurrent respiratory infections including bronchitis or pneumonia.
- Swelling of the neck and face.
- Pain and weakness in the shoulder, arm, or hand.
- Interrupting fever, severe headaches.
- Trouble swallowing.
Additional symptoms depend on the cancer spread and where new tumors form. For example:
In lymph nodes: lumps in the neck or collarbone.
In bones: pain in the back, ribs, or hips.
In brain or spine: headache, dizziness, balance issues, or numbness in arms or legs.
In liver: yellowing of skin and eyes (jaundice).
If one observes any of the above symptoms persisting, they should immediately consult the doctor and get it checked.
DIAGNOSIS OF LUNG CANCER:
After a physical examination, the doctor will tell how to prepare for various diagnostic tests which may include any of the following:
i) Imaging tests:
An X-ray image of lungs may reveal an abnormal mass or nodule. A CT scan can reveal small lesions in the lungs that might not be detected on an X-ray. MRI and PET scans can also be used.
ii) Sputum cytology:
If one has cough and is producing sputum/ phlegm, microscopic examination can determine the presence of lung cancer cells.
iii) Tissue sample (biopsy):
A sample of abnormal cells can be removed by biopsy procedure which can determine if tumour cells are cancerous or not. The biopsy can be performed in several ways:
Bronchoscopy: In this procedure, the patient is under sedation and doctor guides a thin, lighted tube through the nose or mouth and down the air passages to the tumor site, to remove a tiny tissue sample. The instrument used is called a bronchoscope. This procedure is useful for tumors near the centre of the lung.
Mediastinoscopy: In this procedure, an incision is made at the base of the neck; a lighted instrument is inserted and surgical tools are inserted to take tissue samples from lymph nodes. This procedure is done under general anaesthesia.
Needle biopsy: In this procedure, using imaging tests such as X-ray or CT images as a guide, a needle is inserted through the chest wall and into the suspicious lung tissue.
A biopsy sample can also be taken from lymph nodes or other areas where cancer has spread, such as the liver.
Careful analysis of cancer cells in the pathology lab can help in diagnosis.
LUNG CANCER STAGES:
Once lung cancer has been diagnosed, the doctor will try to determine the extent (stage) of your cancer. Knowledge of cancer’s stage helps the doctor to decide the line of treatment.
Tests for determining the stages include Computed Tomography (CT), Magnetic Resonance Imaging (MRI), Positron Emission Tomography (PET) scan and bone scans.
Four main stages in non-small cell lung cancer (NSCLC) are:
Stage 1: Cancer is found in the lung, but it has not spread outside the lung.
Stage 2: Cancer is found in the lung and nearby lymph nodes.
Stage 3: Cancer is in the lung and lymph nodes in the middle of the chest.
Stage 3A: Cancer is found in lymph nodes, but only on the same side of the chest (ipsilateral) where cancer first started growing.
Stage 3B: Cancer has spread to lymph nodes on the opposite side of the chest (contralateral) or to lymph nodes above the collarbone.
Stage 4: Cancer has spread to both lungs, into the area around the lungs, or to distant organs.
Small-cell lung cancer (SCLC) has two main stages:
Limited stage: Cancer is found in only one lung or nearby lymph nodes on the same side of the chest (ipsilateral).
Extensive stage: Cancer has spread:
i. Throughout one lung
ii. To the opposite lung
iii. To lymph nodes on the opposite side
iv. To fluid around the lung
v. To bone marrow
vi. To distant organs
TREATMENT OF LUNG CANCER:
The treatment plan for a patient depends on the type of lung cancer, its stage and spread; side effects of the treatment; patient’s age and overall state of health, patient’s preferences and goals. Various treatment options include:
During surgery, tumorous part of the lung is removed along with a margin of healthy tissue. During surgery, lymph nodes from the chest can also be removed to check them for signs of cancer.
Surgery is an option when cancer hasn’t spread too far in the body. It is usually the best way to treat non-small-cell lung cancer. If one has larger lung cancer, the doctor may recommend chemotherapy or radiation therapy before surgery to shrink cancer. The doctor may recommend chemotherapy or radiation therapy after surgery to rule out the risk of cancerous cells being left behind after surgery or the risk of recurrence.
Various surgical procedures for lung cancer may include:
i. Wedge resection: Removal of a small section of lung that contains the tumor along with a margin of healthy tissue.
ii. Segmental resection: Removal of a larger portion of the lung, but not an entire lobe.
iii. Lobectomy: Removal of an entire lobe of one lung.
iv. Pneumonectomy: Removal of an entire lung.
2) Radiofrequency Ablation:
This procedure is a treatment option in patients who have non-small cell lung cancer and can’t undergo surgery. A needle is guided by the doctor through the skin until it touches the tumor inside the lung and then an electric current is passed through it to heat and kill the cancerous cells.
3) Radiation therapy:
Radiation therapy uses high-powered energy beams from sources such as X-rays and protons to kill cancerous cells. It can be used for both non-small-cell and small-cell lung cancers.
In patients with locally advanced lung cancer, radiation may be used before surgery to shrink a tumor to make it easier to remove or after surgery to kill any cancer cells left behind. It can also be combined with chemotherapy treatments. If surgery cannot be done in a patient, combined chemotherapy and radiation therapy may be the primary treatment.
In patients with advanced lung cancers and those which have spread to other areas of the body, radiation therapy may help relieve symptoms, such as pain or bleeding.
Chemotherapy uses drugs to kill cancer cells. It can be used in both types of lung cancers. One or more chemotherapy drugs may be given through a vein in your arm (intravenously) or taken orally as pills. A combination of drugs usually is given in a series of treatments over weeks or months, with breaks in between so that patient can recover.
Chemotherapy can be used after surgery to kill any cancerous cells that may be left. It can be used alone or in combination with radiation therapy. Chemotherapy may also be used before surgery to shrink cancer size and make the removal easier.
In people with advanced lung cancer, chemotherapy can help to relieve pain and other symptoms.
5) Stereotactic body radiotherapy:
Stereotactic body radiotherapy is also known as radiosurgery. It is an intense radiation treatment aiming many beams of radiation from different angles at cancer. This treatment is typically completed in one or a few treatments. It may be an option for people with small lung cancers who can’t undergo surgery and it may also be used to treat lung cancer spreading to other parts of the body, including the brain.
6) Targeted drug therapy:
Targeted drug treatments focus on specific abnormalities present in cancerous cells, block them and cause cancer cells to die. Some of the drugs include Afatinib, Bevacizumab, Ceritinib, Erlotinib, Gefitinib, etc.
Immunotherapy uses one’s immune system to fight cancer. Drugs used include Atezolizumab, Nivolumab, etc. Immunotherapy treatments are generally done in people with locally advanced lung cancers and cancers that have spread to other parts of the body.
8) Palliative care:
Lung cancer patients experience signs and symptoms of cancer, as well as side effects of treatment. Supportive care, also known as palliative care, is a speciality area of medicine that involves working with a doctor to minimize the signs and symptoms. Palliative care is seen to improve mood and quality of life.
Various medical specialists need to collaborate to collectively plan the treatment of lung cancer. A thoracic surgeon is the one who specializes in the chest and lungs. A pulmonologist is the lung specialist. Oncologists are the ones who treat cancerous tumours (medical oncologist and radiation oncologist). Pathologists work with these doctors to assist in treatment planning and identify if a particular treatment is working or not.
An excellent team of specialists like that of thoracic surgeons, pulmonologists, medical oncologists, radiation oncologists and pathologists can be found under one roof at ‘Kingsway Hospitals, Nagpur’.
At Kingsway Hospitals, the center for cancer has the expertise and technology to provide comprehensive care for patients with all types of cancers, including lungs cancer, solid tumors and other blood-related diseases. The hospital offers a broad scope of cancer-related services, ranging from public education, screening, diagnosis, treatment, pain management, and palliative care.
Stage 3B: Cancer has spread to lymph nodes on the opposite side of the chest (contralateral) or to lymph nodes above the collarbone