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The Pathophysiology of Lung Cancer

By Anaya Garg

Highlights

  • What is Lung Cancer?

  • Symptoms and Diagnosis

  • Treatment Options

  • How lung cancer affects other body systems

Introduction:


Lung cancer is the leading cancer killer of both men and women in America. Nearly 400,000 people in the US are living with lung cancer. 81% of those living with lung cancer are over the age 60. Cancer is essentially when a cell begins to irregularly divide, usually due to a gene mutation, that causes the irregular cell to pass all the checkpoints in the body. Lung cancer is, as the name suggests, a cancer of the lungs, where the cells that line the airway, in the Bronchi, and parts of the lungs, such as the Bronchioles and Alveolus, are the most commonly affected. There are 4 main types of lung cancer:

  • Small Cell Lung Cancer

  • Non-small cell lung cancer

  • Mesothelioma

  • Lung Nodules

Non-small lung cancer is more common than small cell lung cancer. In more advanced stages (Stage 3 or 4), the cancer generally spreads to the lymph nodes, and due to the lymphatic system’s circulation throughout the body, it can lead to tumors in various spots that originated from the lung tumors, and this is referred to as metastasis.


Symptoms and Diagnosis:

Some Symptoms of Lungs Cancer include

- Shortness of Breath (due to airway obstruction and/or fluid buildup in the lung)

- Chest Pain (also known as Angina)

- Bone Pain (usually a sign that the cancer may have metastasized to the bones)

- Headache (usually a sign that the cancer may have metastasized to the brain)

- Weight loss

- Feeling tired

- Lumps and bumps around your collarbone, neck, or armpits; neck or facial swelling (the cancer may have metastasized to the lymph nodes)

- Yellowing of the skin and the whites of your eyes (more extreme sign of cancer metastasizing to the liver)

- pain on your right side

- feeling sick after eating rich food


Diagnosis Options:

- X-Ray scanning: An X-ray image of your lungs may reveal an abnormal mass or nodule; A chest X-ray is usually the 1st test used to diagnose lung cancer.

- Most lung tumors appear on X-rays as a white-grey mass

- CT Scanning: A CT scan can reveal small lesions in your lungs that might not be detected on an X-ray

- Sputum Smear Analysis: If you have a cough and are producing sputum, looking at the sputum under the microscope can sometimes reveal the presence of lung cancer cells.

- Other types of scans that can be used include MRI and PET scans

- MRI and PET scans are most often used to see if the lung cancer has spread beyond its initial site.

Some forms of additional testing include a biopsy, ultrasound, mediastinoscopy, thoracoscopy, or wedge resection- only needed if a doctor suspects cancer but can’t actually diagnose it through scanning methods, i. e., if he suspects that a nodule/ lesion surfacing on the CT Scan or X-Ray is cancerous, he/she may order a tissue biopsy to ensure whether or not the tissue is cancerous, and what type of cancer it is.


Treatment Options

  • Surgery: Dependent on the tumor size in the lung

    • Wedge resection: remove a small section of the lung that contains the tumor along with a margin of healthy tissue

    • Segmental resection: remove a larger portion of the lung, but not an entire lobe

    • Lobectomy: remove the entire lobe of one lung

    • Pneumonectomy: remove an entire lung

      • During surgery, the doctor may also remove lymph nodes from your chest in order to check them for signs of cancer.

      • Surgery may be an option if your cancer is confined to the lungs. If you have a larger lung cancer, your doctor may recommend chemotherapy or radiation therapy before surgery in order to shrink the cancer. If there's a risk that cancer cells were left behind after surgery or that your cancer may recur, your doctor may recommend chemotherapy or radiation therapy after surgery.

  • Radiation therapy: Radiation therapy uses high-powered energy beams from sources such as X-rays and protons to kill cancer cells.

    • With locally advanced lung cancer, radiation may be used before surgery or after surgery. It's often combined with chemotherapy treatments. If surgery isn't an option, combined chemotherapy and radiation therapy may be your primary treatment.

    • For advanced lung cancers and those that have spread to other areas of the body, radiation therapy may help relieve symptoms, such as pain.

  • Chemotherapy: (Pretty similar to Radiotherapy, but the method of operation is different)

Chemotherapy uses drugs to kill cancer cells. The drugs may be administered intravenously or taken orally. A combination of drugs usually is given in a series of treatments over a period of weeks or months, with breaks in between so that you can recover (also kills other bodily cells in addition to cancer cells, since the drugs target rapidly dividing cells, which is the cause of hair loss and feelings of nausea during a chemotherapy treatment, because our hair cells, and the cells lining our intestinal walls are rapidly dividing cells.)

  • Chemotherapy is often used after surgery to kill any cancer cells that may remain. It can be used alone or combined with radiation therapy. Chemotherapy may also be used before surgery to shrink cancers and make them easier to remove.

  • In people with advanced lung cancer, chemotherapy can be used to relieve pain and other symptoms.

  • Immunotherapy: uses your immune system to fight cancer.

    • Our body's disease-fighting immune system may not attack the cancer cells because the cancer cells produce proteins that help them hide from the immune system cells. Immunotherapy works by interfering with that process.

  • Immunotherapy treatments are generally reserved for people with locally advanced lung cancers and cancers that have spread to other parts of the body.

  • Palliative Care is also generally paired with other forms of treatment in order to alleviate the symptoms and side effects that the patient is experiencing due to the treatment, or due to the advanced stage of cancer

Affect on Other Body Systems


Lung Cancer’s effect on the other body systems is generally based on the metastasis of the tumor.In terms of the Cardiovascular system, lung cancer causes one to be at an increased risk for blood clots, which can lead to a pulmonary embolism. It doesn’t happen often, but lung cancer can spread to the heart or the pericardial sac. The pericardial sac is the tissue that surrounds the heart. Cancer treatment, such as radiation therapy can be toxic to the cells of the heart, and may cause myocarditis, myocardial infarction, or necrosis of heart cells. Damage to the heart may be immediately apparent, but it sometimes takes years to detect. Cancer metastasis to the heart can also lead to fluid buildup inside the sac around the heart (called a pericardial effusion). The fluid can press on the heart and affect how well it works.


As mentioned previously, the cancer can metastasize from the lungs by entering nearby lymph nodes. Once in the lymphatic system, the cells can reach other organs and form new tumors. One of the common sites for lung cancer to spread is the liver, which can cause jaundice. In extreme cases of lung cancer, that has metastasized to the brain, can lead to vision problems, memory loss, chronic dizziness, etc. Cancer that spreads to the bones can lead to bone and muscle pain, weakened bones, and an increased risk of fracture.


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