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Lung cancer is one of the most commonly occurring cancers worldwide. Lung cancer occurs in the lungs when the cells in the lungs start proliferating abnormally, resulting in a high mortality rate.

Types of Lung Cancer

The most prevalent types of lung cancer are found right in the lungs, and other rarer types of cancer occur in the lungs and chest wall. It can be categorized based on the size of the affected cells.

In general, lung cancer is categorized broadly into two types.
1. Non-small cell lung cancer (NSCLC)
2. Small cell lung cancer (SCLC)

Non-small cell lung cancer: This is a most common type of cancer that develops and spreads more slowly than small-cell lung cancer. It accounts for almost 80% of all lung cancer cases. The following are the three subtypes of non-small cell lung cancer:

  • Adenocarcinoma: This is the most common kind of lung cancer in both smokers and nonsmokers. It occurs in the outer area of the lung and develops in the cells of the epithelial tissues that line the body's cavities and surfaces and form glands.
  • Large cell carcinoma: These tumors may start anywhere in the lungs and tend to grow quickly. Large cell neuroendocrine carcinoma, a sub-type of large cell carcinoma, is fast-growing and is similar to small cell lung cancer.
  • Squamous cell carcinoma: It starts in the middle of the lungs near the bronchi, and it is otherwise known as epidermoid carcinoma.

Small cell lung cancer: Small cell lung cancer is fast-growing and the least commonly occurring lung cancer. It is classified further into two sub-types which include:

  • Small cell carcinoma: It is also known as oat cell cancer, and it is caused by a DNA mutation of the lung cells.
  • Combined small cell carcinoma: Combined small cell contains the components of both SCLC and non-small cell lung cancer (NSCLC).

Rare Types of Lung Cancer

Rare types of lung cancer that occur in the lung and chest wall include the following:

Mesothelioma: It is a type of cancer in the lining of the chest. Exposure to asbestos is a major risk factor for mesothelioma, and it accounts for around 5% of all lung cancer cases. The various treatment methods for this condition involve chemotherapy, radiation therapy, and surgery based on the condition and stage.

Chest Wall Tumors: These tumors are found in the chest wall and might be malignant or benign. There are two kinds of chest wall tumors:

  • Primary tumors: These tumors begin in the bones or muscles of the chest wall.
  • Metastatic tumors: These tumors are malignant and have spread to the chest wall from cancer that began elsewhere, such as in the breast.

Carcinoid Tumors: This rare type of cancer can develop in the stomach or intestines. However, they can also begin in the lung. Carcinoid tumors are categorized as follows:

  • Typical carcinoids: It grows slowly and rarely spreads beyond the lungs.
  • Atypical carcinoids: It grows faster and spreads outside the lungs.
  • Central carcinoids: It develops in the bronchi, which are large airways located near the center of the lungs.
  • Peripheral carcinoids: It develops in the bronchi, which are small airways located in the middle of the lungs.

Mediastinal Tumors: They develop in the mediastinum, the chest area that separates the lungs, and it is enclosed by the breastbone in front and the spine in the back. Mediastinal tumors are categorized as follows:

  • Germ cell tumors: These tumors are highly treatable and often cured. It occurs in both men and women reproductive systems and develops from reproductive cells. It is also called extragonadal germ cell tumors.
  • Lymphomas: These cancers begin in the lymphatic system that includes hodgkin’s lymphoma and non-hodgkin’s lymphoma. It can develop in the lungs in rare cases.
  • Teratomas: These tumors are cysts containing one or more layers of embryonic cells found in the chest. The layers are known as endoderms, and mesoderms.

Stages of Lung Cancer

The TNM staging tool is the common tool used in determining the stages of lung cancer.

Non-small cell lung cancer (NSCLC):

Stage 0 (carcinoma/tumor in-situ): It is an early stage of lung cancer that has not grown to the nearby normal lung tissues or spread outside the lung.

Stage I A: The tumor in this stage is minimally invasive, and cancer has not spread to lymph nodes and has not reached the other distant body parts.

Stage I B: The Cancer has not spread to nearby lymph nodes or to distant parts of the body, and its size is more than 3 cm and less than 4 cm.

Stage II A: In this stage, the size of the tumor will be more than 4 cm but lesser than 5 cm. It has grown into the main bronchus, and the tumor is partially clogging the airways. However, cancer has not spread to lymph nodes and has not reached the other distant body parts.

Stage II B: In this stage, cancer has spread to lymph nodes within or around the lung where the bronchus enters the lung (hilar lymph nodes).

Stage III: Cancer is found to be spread in the lung and lymph nodes in the middle of the chest in this stage.

Stage IIIA: Cancer occurs in lymph nodes, but only on the same side of the chest where the cancer first started growing.

Stage III B: Cancer has spread to lymph nodes on the opposite side of the chest or to lymph nodes above the collarbone.

Stage IV: It is the most advanced form of lung cancer. In stage IV, cancer has spread to both lungs, into the area around the lungs, or to distant organs.

Small-cell lung cancer (SCLC):

Limited stage lung cancer: It only affects one lung with or without spread to the lymph nodes in the mediastinum (area in the chest between the lungs).

Extensive stage lung cancer: It has spread to tissue outside of the originally affected lung like the opposite lung or distant organs.

Causes & Risk Factors of Lung Cancer

  • Smoking: Smoking is the most common cause of increased lung cancer incidences. Certain tobacco products, like cigars or pipes, also raise the risk of lung cancer and smokers have a higher risk of lung cancer than those who do not. Smoking cessation at any age can lower your risk of getting lung cancer.
  • Second-hand smoke: Whether you smoke or not, inhaling second-hand smoke from burning cigars and other tobacco products can increase your chance of developing lung cancer.
  • Radon exposure: Radon is a naturally occurring radioactive gas produced by the breakdown of uranium in soil and rocks. Radon exposure is the second leading risk factor for lung cancer.
  • Asbestos exposure: Exposure to asbestos, including mines, mills, textile plants, places where insulation is used, and shipyards, enhance a person's risk of getting mesothelioma, a type of cancer that begins in the pleura (the lining surrounding the lungs).
  • Exposure to carcinogens: Cancer-causing agents (carcinogens) such as uranium, arsenic, beryllium, cadmium, silica, vinyl chloride, nickel compounds, chromium compounds, coal products, mustard gas, chloromethyl ethers, and diesel exhaust might raise the chance of acquiring lung cancer.
  • Family or personal history: A past history of lung cancer raises your chances of getting it again, and a family history of lung cancer is also a risk factor.
  • Radiation therapy to the chest: Having undergone previous radiation therapy to the chest may increase the risk of getting lung cancer, especially while smoking.
  • Pollution: According to studies, breathing polluted air increases the risk of acquiring lung cancer.

Symptoms of Lung Cancer

Early Symptoms of Lung Cancer:

  • Persistent cough
  • Coughing up phlegm or blood
  • Fatigue
  • Wheezing
  • Shortness of breath
  • Unexplained weight loss
  • Pain in the chest
  • Hoarseness
  • Headache
  • Loss of appetite
  • Recurrent respiratory infections like pneumonia or bronchitis

Late Symptoms Of Lung Cancer:

  • Jaundice (yellowing of skin and eyes)
  • Seizures
  • Swollen lymph nodes in the neck
  • Lumps in the neck or collarbone
  • Dizziness
  • Trouble balancing
  • Pain in the shoulder
  • Swelling of the face and upper body
  • Trouble swallowing
  • Fatigue
  • Weakness
  • Drooping of the eyelid
  • Pain in the bones of the back, ribs, or hips

Lung Cancer Screening

Screening tests are performed when you are healthy and have no signs or symptoms of the disease, and they can aid in the early detection of malignancies so successful treatment can begin. Low-dose computed tomography (LDCT or low-dose CT) is the only screening test for lung cancer. Low-dose radiation is used during this LDCT examination to get detailed images of the lungs that assist in detecting abnormalities. It is otherwise known as a spiral scan or helical scan.

Adults between the age of 50 and 80 who have quit smoking within the previous 15 years or who are still smoking and have a smoking history of at least 20 packs per year are advised to take this screening test. A pack-year is smoking an average of 1 pack of cigarettes each day for one year.

Lung Cancer Diagnosis

A lung cancer diagnosis is usually made after any symptoms appear or if screening tests indicate the risk of cancer. The type of diagnostic tests varies depending on the type of cancer, symptoms, age, and the results of the previous testing.

Your doctor may begin by performing a lung examination. If your doctor finds anything suspicious, they may order diagnostic imaging tests to examine further. The medical expert will ask about your medical history, family history, and symptoms.

  • Chest x-ray: A chest x-ray is an energy beam that can detect abnormal areas in the lungs.
  • CT scan: Computed tomography (CT scan) is more likely to detect lung cancer than a chest x-ray, and it can also detect enlarged lymph nodes and indicate the position, size, and shape of any lung tumors.
  • PET-CT scan: PET-CT scan, or positron emission tomography-computerized tomography, can identify the locations of cancer cells that are actively growing. This scan is painless and used to detect the early stages of cancer.
  • Sputum cytology: It is a procedure in which a sputum sample is examined under a microscope for cancer cells.
  • Tissue specimen (biopsy): A biopsy is a process that removes a sample of aberrant cells. It can be done in several methods by your doctor, including bronchoscopy, which involves passing a lighted tube down your neck and into your lungs to examine for abnormal lung tissue.

Lung Cancer Treatment

Depending on the individual's age, type of lung cancer, the extent of cancer, tolerance to medication, and the patient's preference, the doctor may recommend the treatment options. The major treatment types for lung cancer include surgery, radiation therapy, chemotherapy, immunotherapy, targeted therapy, and immunotherapy, and you may receive one or a combination of these treatment types.

Surgery is the primary treatment for early-stage lung cancer. The type of surgery depends on the size and location of the tumor in the lung, the degree of the malignancy, the patient's general health, and other considerations. Lung cancers commonly occur in smokers over the age of 50, who often have other chronic diseases that increase the risk of surgery.

Types of Lung cancer surgery include:

  • Segmental or wedge resection: Removal of only a small part of the lung
  • Lobectomy: Removal of an entire lobe of the lung
  • Pneumonectomy: Removal of an entire lung
  • Sleeve resection: Removal of a smaller section of bronchus, after which the lung is reattached to the remaining part of the bronchus

Radiation therapy uses high-energy X-rays or protons to break and damage the DNA of cancer cells. This damage inhibits malignant cells from proliferating. Cells with damaged DNA die and are removed by the body. For people with local and advanced lung cancer, radiation therapy may be used before or after surgery. It is often combined with chemotherapy treatments.

Chemotherapy is the use of medications to destroy cancer cell growth. In most situations, chemotherapy is administered via IV infusion. Chemotherapy is used to treat lung cancer at all stages. If there is a high risk of cancer recurrence, chemotherapy can be given to reduce the recurrence risk. For people with advanced lung cancer, chemotherapy helps to relieve pain and other symptoms.

Targeted therapy can precisely identify and target the genes or proteins involved in cancer cell proliferation and multiplication, halting cancer progression. Lung cancer is treated with a variety of targeted therapy medications, although the majority are only
prescribed for patients with advanced or recurring cancer. Some targeted treatments are only effective in patients whose cancer cells have specific genetic mutations.

Immunotherapy is a new cancer treatment technique that employs medicines, vaccines, and other therapies to boost the immune system's natural defenses so that it can fight cancer. Patients with local and advanced lung cancer that has metastasized to other areas of the body can benefit from immunotherapy treatments. Pembrolizumab, atezolizumab, and nivolumab are the three immunotherapy drugs that have been approved to treat certain non-small cell lung cancers.

Complementary therapies such as aromatherapy, acupuncture, or massage can help reduce the pain and improve your emotional well-being along with your major cancer treatment.

Lung Cancer Prognosis

According to the National Cancer Institute, the prognosis is defined as, "The likely outcome or course of a disease; the chance of recovery or recurrence."

Lung cancer prognosis depends upon various factors such as:

  • Age
  • Status of the cancer
  • Patient's response to the treatment
  • Metabolic factors
  • Overall patient health
  • Gene changes in cancer cells
  • Recurrence of cancer after its treatment
  • Cancer stage
  • Stage of diagnosis of the cancer

What can be done to increase the survival rate?

Early screening for cancer is the greatest method to treat it as soon as possible, thereby enhancing survival rates. Regular screening practices can assist ensure early detection and treatment of cancer.

Prevention of Lung Cancer

  • Quit smoking: The number one risk factor for developing lung cancer is smoking. Stop smoking if you're a smoker. And if you don't already smoke, don't start. Avoid secondhand smoke to reduce your risk of developing lung cancer.
  • Prevent radon exposure: Get your home tested for radon and decrease your exposure to it because it is a potential risk factor for developing lung cancer, and its prevention can reduce the risk.
  • Avoiding exposure to other carcinogens: Lung cancer can be avoided by taking the necessary precautions, such as wearing a face mask, when exposed to other carcinogens such as arsenic, asbestos, chromium, and nickel at the workplace.
  • Lung cancer-reducing foods: According to studies, eating a nutritious diet rich in fruits and vegetables and staying well-hydrated aids in reducing the risk of developing lung cancer.

Lung Cancer FAQs

1. Is lung cancer aggressive?

Yes, Small-cell lung cancer is an aggressive form of lung cancer. It grows faster than non-small-cell lung cancer and creates large tumors.

2. Is genomic testing an option for me?
Yes, advanced genomic testing has a great option for some lung cancer patients, especially those who have non-small cell lung cancer. It investigates cancer at the cellular level, identifying DNA mutations that are responsible for a specific tumor's growth.

3. Will my lung cancer recur?

Yes, lung cancer comes back and it can occur at any time. Recurrence depends on several factors, including the original treatment strategy, the type of lung cancer, and the stage of diagnosis.

4. How is lung cancer diagnosed?

The following tests may be performed by your doctor to see if you have lung cancer:

  • Complete medical history
  • Physical exam
  • Chest X-ray, or other X-ray procedures such as CT scan
  • Sputum cytology
  • Needle biopsy of a mass
  • Bronchoscopy

5. What are the treatments for lung cancer?

There are three main treatment options for lung cancer. It may be used separately or in combination. The treatment plan is chosen based on the stage and type of lung cancer.

The three treatments are:

  • Surgery
  • Chemotherapy
  • Radiation therapy
  • Targeted therapy
  • Immunotherapy

6. Does lung cancer spread quickly?

Yes, Lung cancer spreads rapidly. The majority of lung cancer first invade lymph nodes within the lung or near the airways. Early detection and treatment increase a person's chances of survival from lung cancer.

7. What is AAT deficiency?

AAT deficiency or Alpha-1 antitrypsin deficiency is a condition that increases your chances of acquiring lung disease. Your risk increases substantially if you smoke in addition to having an AAT deficiency.

8. What are the chances of getting lung cancer if I have chronic obstructive pulmonary disease (COPD)?

Smoking cigarettes damages the lungs, which can result in lung cancer and COPD. Physicians cannot predict your individual risk of acquiring lung cancer. If you have a history of smoking and are 55 years of age or older, discuss lung cancer screening with your physician.

9. Is second-hand smoke a risk factor for lung cancer?

Yes, prolonged exposure to secondhand smoke increases the risk of developing lung cancer as well as chronic bronchitis and other upper respiratory conditions. However, you can reduce this risk by requesting others to smoke outside.


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