Types, Risks and Signs of Lung Cancer

Lung carcinomas are divided into two groups based on how the cells look. One group is called small cell lung cancer and the other group is called NSCLC (non-small cell lung cancer). The second group is much more common. There are two major types of NSCLC. The first type is non-squamous carcinoma. It includes adenocarcinomas, large-cell carcinomas, and rare cell types. The second type of NSCLC is squamous cell carcinoma. It is also sometimes called epidermoid carcinoma.


Cells have a control center called the nucleus. The nucleus contains chromosomes, which are long strands of DNA (deoxyribonucleic acid) tightly wrapped around proteins. Within DNA are coded instructions for building new cells and controlling how cells behave. These instructions are called genes. There can be abnormal changes in genes called mutations. Some types of mutations that are linked to cancer are present in all cells. Other mutations are present only in cancer cells. Mutations cause cancer cells to not behave like normal cells and, sometimes, to look very different from normal cells.


A risk factor is anything that increases your chance of lung cancer. Risk factors can be activities that people do, things in the environment, or personal data like age and health. If these risk factors describe you, it doesn’t mean you have lung cancer. Likewise, lung cancer occurs in some people who have no known risk factors.

Tobacco smoke

Smoking tobacco is the biggest risk factor for lung cancer. There are more than 50 compounds in tobacco smoke known to cause cancer. Any smoking increases your risk for lung cancer. However, the more you smoke, the higher your risk.

If you quit smoking, your risk will decrease. However, the risk for lung cancer is higher for former smokers than for people who never smoked. Thus, current or past tobacco smoking is a risk factor for lung cancer.

In 1981, a link between second-hand smoke and lung cancer was first suggested. Since then, other studies have found the risk for lung cancer is greater for people exposed to second-hand smoke. However, the risk may depend on how much contact a person has had.

Older age

As you get older, you are more likely to get cancer. Half of the people who were diagnosed with lung cancer in recent years were 70 years old or older. Only 12 out of every 100 people with lung cancer were younger than age 55.

Having had cancer

Your risk for lung cancer may be increased if you’ve had certain types of cancer. Having had any type of lung cancer increases your risk for other types of lung cancer. If you had lymphoma, you are more likely to get lung cancer. If you’ve had a smoking- related cancer, your risk for lung cancer is increased. These cancers include head and neck, kidney, bladder, pancreatic, stomach, and cervical cancers and AML (acute myeloid leukemia).

Some cancer treatments also increase risk. The risk for lung cancer increases after receiving radiation therapy in the chest, especially if you smoke. Treatment of Hodgkin’s lymphoma with an alkylating agent—a type of cancer drug—increases the risk for lung cancer too.

Family who’ve had lung cancer

If your parent, sibling, or child has had lung cancer, your risk for lung cancer is higher than a person with no family history. Your risk is even higher if your relative had cancer at a young age. Your risk is also higher if more than one relative has had lung cancer.

Cancer-causing agents

There are 11 agents known to cause lung cancer. You are more likely to have lung cancer after having major contact with these agents. The risk after exposure is higher for those who smoke than for those who don’t smoke.


Exposure to asbestos can cause lung cancer, especially if you smoke. Asbestos is a group of minerals made of tiny fibers. It has been used in housing and commercial products, such as roofing and brake pads. Asbestos can break into tiny pieces that may be breathed in or swallowed. The pieces can then get trapped in the lungs and remain there for years.

Uranium and radon

Uranium is a cancer-causing agent. It is a substance found in rocks and soil. As it decays, a gas called radon is made and gets into air and water.Miners of uranium have a high risk of developing lung cancer. Some studies of radon found in the home have linked radon to lung cancer, while other studies have not. The risk for lung cancer may depend on how much radon is in the home.

Other agents

Five metallic metals known to cause lung cancer are arsenic, beryllium, cadmium, chromium, and nickel. Other cancer-causing agents include coal smoke, soot, silica, and diesel fumes.

Other lung diseases

Two lung diseases have been linked to lung cancer. A history of COPD (chronic obstructive pulmonary disease) increases your risk for lung cancer. COPD makes breathing hard because the lung tissue is damaged or there’s too much mucus. The second disease linked to lung cancer is widespread pulmonary fibrosis. Pulmonary fibrosis is major scarring of lung tissue that makes it hard to breathe.

Signs of lung cancer.

Sometimes, a lung nodule is found by chance with imaging. Such imaging includes CT (computed
tomography) and PET (positron emission tomography). Your radiologist will review the images to decide if the nodule may be cancer. Important test results are the features of the nodule, abnormal lung tissue, and PET hot spots.

Features of the nodule

Nodules caused by cancer have specific traits. First, they aren’t likely to have calcium buildup. Second,
they often have rough edges and odd shapes. Other very important features are the nodule size and

Size Nodules with cancer often grow faster and are larger than ones without cancer. Thus, nodules that are
large are more likely to be cancer than small nodules.

Density The density of the nodule is also assessed to decide if the nodule may be cancer. Non-solid nodules have low density. Solid nodules have high density. Part-solid nodules have both high and low areas of density. Part-solid nodules are found less often than solid nodules,but more of them are caused by cancer. On the other hand, solid nodules that are cancer grow faster than part-solid nodules that are cancer.

Abnormal lung tissue Besides nodules, imaging may show other abnormal findings. It may show tissue inflammation, tissue scarring, or both. A nodule is more likely to be cancer if there’s inflammation or scarring than if neither is present.

PET hot spots PET shows how your cells are using a simple form of sugar (glucose). To create the pictures, a sugar radiotracer is put into your body. The radiotracer emits a small amount of energy that is detected by the imaging machine. Cancer quickly uses glucose so it appears “hot” in images. Other health problems can also cause hot spots, too. Cancer detected by PET often needs to be confirmed with other testing.

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