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Lung cancer begins with lung cells that have changed, multiplied, and then grouped to form a tumor. This cancer can spread through your body but is still called lung cancer because of where the first altered cells originated.

There are two main types of lung cancer.

Most lung cancers are called non-small cell lung cancer (NSCLC). This group includes:

  • adenocarcinoma
  • squamous cell carcinoma
  • large cell carcinoma
  • ALK-positive lung cancer

The second, smaller category is called small cell lung cancer (SCLC) and is sometimes also called oat cell cancer.

Cancer in your body can affect the white blood cells (WBC) of your immune system. WBCs are made in bone marrow and found in blood and lymphatic fluid. There are several different types of WBCs, all of which work together to protect you from disease and infection.

A normal WBC count ranges from 3,700 to 10,500 per microliter of blood. A count that’s too high or too low tells your doctor that you may have a condition that needs medical help. Lung cancer is one such condition: Your WBC count might be out of range when you’re diagnosed.

Lung cancer can cause a high WBC count because of infections like bronchitis or pneumonia that can happen along with cancer. WBC counts increase when the immune system fights these infections.

The chemotherapy used to treat cancer can interfere with the normal function of your bone marrow. This is where your WBCs are made.

Chemotherapy affects your entire body, so it can reach the cells of your bone marrow even though the cancer it’s treating may be elsewhere in your body. Damage to white blood cells can cause your WBC count to drop.

Radiation therapy is confined to a specific location, but if the treatment area includes large bones that produce marrow, this can also cause your WBC count to decrease.

A viral infection can also affect your WBC count. If the infection disrupts the white cell production in your bone marrow, your WBC count will decrease.

Sometimes, cancer growth in bone marrow can interfere with the normal production of WBCs which lowers their count.

If cancerous cells from your lungs have spread to your bone marrow and then multiplied, this is called metastasis. Bone metastases happen in 30 percent to 40 percent of lung cancer cases.

Lung cancer is not diagnosed with bloodwork. Instead, lung cancer is usually discovered because it causes symptoms. Doctors make their final diagnosis after examining a sample of lung cells in a lab.

Information and procedures that doctors can use to diagnose lung cancer and monitor its spread include:

  • medical history
  • physical exam
  • imaging tests like X-rays, CT scans, MRI scans, PET scans, and bone scans
  • sputum cytology (analysis of lung mucus)
  • thoracentesis (analysis of fluid around the lungs)
  • needle biopsy (analysis of cells removed from a mass)
  • bronchoscopy (insertion of a camera-equipped tube into your nose or mouth, down through your windpipe and into your lungs)
  • thoracoscopy (insertion of a camera-equipped tube through a small incision between your ribs, into the space in your chest outside your lungs)
  • ultrasound
  • lung function tests

Bloodwork is still important for your doctor to assess your overall health and to see whether you’re a candidate for certain treatments, like surgery.

WBCs are an important part of your immune system. They help you fight infection and are most effective when their numbers fall within a certain range.

A WBC count that’s too low means that you’re at risk for infection. Your doctor will monitor your WBC during treatment to make sure that it doesn’t get too low.

Your WBC is so important that if treatment causes it to drop too far, your doctor will temporarily stop the treatment. Once your WBC returns to safe levels, cancer treatment can resume.

Tell your doctor right away if you experience any signs of low WBC count, which include:

  • chills
  • fever
  • sweating

Self-care is always important, but even more so if you have a low WBC count. Eat a nutritious diet, get plenty of rest, and avoid germs and injury as much as possible.

Immunotherapy helps your body fight cancer using your own immune system. This therapy makes your existing white blood cells more effective against cancer by helping them recognize and destroy cancer cells.

Cancer cells grow because they can interfere with your immune system in ways like these:

  • They have surface proteins that turn off your immune system response.
  • They have genetic properties that help them hide from your immune system.
  • They can change the healthy cells around them, so these cells get in the way of the immune system.

Immunotherapy helps correct these issues. Types of immunotherapy include:

  • Immune checkpoint inhibitors. Your immune system has checkpoints that stop it from overreacting and harming healthy cells. Immune checkpoint inhibitor drugs suppress these checkpoints, so your immune system is more active and can fight cancer.
  • T-cell transfer therapy. Active T-cells attacking your tumor are removed, changed so that they’re more effective, grown in large batches, and then returned to your blood stream.
  • Monoclonal antibodies. These are immune system proteins that are made in a lab and used in your body to mark cancer cells so your immune system can find them.
  • Treatment vaccines. These vaccines are made from your own tumor cells to help your immune system learn to attack those cells.

Your WBCs protect your body from infection. If you have too many or too few, this can tell your doctor that you might have a condition that needs treatment. Lung cancer is one such condition.

Lung cancer originates in your lungs but can spread through your body. It’s diagnosed by a cell analysis in a lab.

Cancer treatments like chemotherapy and radiation can lower your WBC count, which can increase your infection risk. Your doctor will monitor your blood count levels and adjust treatment as necessary.

Immunotherapy is a cancer treatment that works by strengthening your immune system.

Cancer grows because it can interfere with your immune system, so the goal of immunotherapy is to compensate for this issue and make your immune system stronger.