Diagnosing Lung Cancer

Lung Cancer is the most common cancer in the world. According to the American Lung Association, 2.1 million new cases were reported in 2018, followed by as many as 1.8 million deaths from lung cancer. The most common type is non-small cell lung cancer (NSCLC) which makes about 80-85 percent of all cases. Thirty percent of these cases start in the cells that form the lining of the body’s cavities and surfaces. This type usually forms in the outer part of the lungs (adenocarcinomas). Another 30 percent of cases begin in cells that line the passages of the respiratory tract (squamous cell carcinoma). A rare subset of adenocarcinoma begins in the tiny air sacs in the lungs (alveoli). It’s called adenocarcinoma in situ (AIS). This type isn’t aggressive and may not invade surrounding tissue or need immediate treatment. 

Faster-growing types of NSCLC include large-cell carcinoma and large-cell neuroendocrine tumors. Small-cell lung cancer (SCLC) represents about 15-20 percent of lung cancers. Tumors in the lungs can grow quite large before you notice symptoms. Early symptoms mimic a cold or other common conditions, so most people don’t seek medical attention right away. That’s one reason why lung cancer isn’t usually diagnosed in the early stage.

Non small cell lung cancer (NSCLC):

The three types are adenocarcinoma, squamous cell carcinoma, and large cell carcinoma.

Adenocarcinoma – This is the most common type and starts in the mucus making gland cells in the lining of your airways.

Squamous cell cancer – This type develops in the flat cells that cover the surface of your airways. It tends to grow near the centre of the lung.

Large cell carcinoma – The cancer cells appear large and round under the microscope.

Symptoms of non-small cell lung cancer and small cell lung cancer are basically the same.

Early symptoms may include:

•     lingering or worsening cough
•     coughing up phlegm or blood
•     chest pain that worsens when you breathe deeply, laugh, or cough
•     hoarseness
•     shortness of breath
•     wheezing
•     weakness and fatigue
•     loss of appetite and weight loss

From the moment you inhale smoke into your lungs, it starts damaging your lung tissue. The lungs can repair the damage, but continued exposure to smoke makes it increasingly difficult for the lungs to keep up the repair. Breathing in other hazardous substances, especially over a long period of time, can also cause lung cancer. A type of lung cancer called mesothelioma is almost always caused by exposure to asbestos.

Other substances that can cause lung cancer are:

   – arsenic

    -cadmium

    -chromium

    -nickel

    -petroleum products

    -uranium

Inherited genetic mutations may make one more likely to develop lung cancer, especially if you smoke or are exposed to other carcinogens. Back pain is fairly common in the general population. It’s possible to have lung cancer and unrelated back pain. Most people with back pain don’t have lung cancer. Not everyone with lung cancer develops back pain, but many do. For some people, back pain turns out to be one of the first symptoms of lung cancer. Back pain can be due to the pressure of large tumors growing in the lungs. It can also mean that cancer has spread to your spine or ribs. As it grows, a cancerous tumor can cause compression of the spinal cord.

That can lead to neurologic deterioration causing:

    -weakness of the arms and legs

    -numbness or loss of sensation in the legs and feet

    -urinary and bowel incontinence

    -interference with the spinal blood supply

Diagnosing Lung Cancer

After a physical examination, your doctor will tell you how to prepare for specific tests, such as:  Imaging tests: An abnormal mass can be seen on X-ray, MRI, CT, and PET scans. These scans produce more detail and find smaller lesions. 

Sputum cytology: If you produce phlegm when you cough, microscopic examination can determine if cancer cells are present.

A biopsy can determine if tumor cells are cancerous. A tissue sample can be obtained by:

Bronchoscopy: While under sedation, a lighted tube is passed down your throat and into your lungs, allowing closer examination.

Mediastinoscopy: The doctor makes an incision at the base of the neck. A lighted instrument is inserted and surgical tools are used to take samples from lymph nodes. It’s usually performed in a hospital under general anesthesia.

Needle: Using imaging tests as a guide, a needle is inserted through the chest wall and into the suspicious lung tissue. Needle biopsy can also be used to test lymph nodes.

Tissue samples are sent to a pathologist for analysis. If the result is positive for cancer, further testing, such as a bone scan, can help determine if the cancer has spread and to help with staging.

For this test, you’ll be injected with a radioactive chemical. Abnormal areas of bone will then be highlighted on the images. MRI, CT, and PET scan are also used for staging.