SNP Shot: Genomic Insights

Lung cancer develops when lung cells change and grow out of control, forming a mass called a tumor. Early lung cancer might not cause any noticeable signs or symptoms. However, some people with lung cancer may experience symptoms such as pain in the chest, a cough that won't go away, blood in the sputum, shortness of breath, difficulty swallowing or talking, loss of appetite and weight, feeling tired, or swelling in the face or neck. If the cancer spreads to other parts of the body (metastasis), additional symptoms may occur. Lung cancer is most often diagnosed in adults in their 60s and 70s. While smoking for a long time is the biggest risk factor, lung cancer can also affect people who have never smoked.

Lung cancer is generally categorized into two main types: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). This categorization is based on how the cancer cells look under a microscope. NSCLC is the more common type, making up about 85% of all lung cancer cases, while SCLC makes up the other 15%.

SCLC is a fast-growing and aggressive type of cancer. Often, by the time it's discovered, it has already spread beyond the lungs in more than half of all cases. Common places where SCLC spreads include the liver, brain, bones, and adrenal glands (small glands on top of the kidneys that make hormones). The outlook for SCLC is usually poor, with most people living for about one year after they are diagnosed, and less than 7% living for five years or more.

NSCLC is further broken down into three main subtypes: adenocarcinoma, squamous cell carcinoma, and large cell carcinoma. Adenocarcinoma starts in the cells lining the alveoli, which are the tiny air sacs in the lungs. Squamous cell carcinoma arises from squamous cells, which line the airways that connect the trachea (windpipe) to the lungs (bronchi). Large cell carcinoma develops from the epithelial cells that line the lungs. Large cell carcinoma is a term used for NSCLC tumors that don't have the characteristics of adenocarcinoma or squamous cell carcinoma. The 5-year survival rate for people with NSCLC is usually between 11% and 17%, but this can change depending on the specific subtype and how advanced the cancer is.

Inheritance:

In most situations, lung cancer doesn't come from inherited genetic mutations. These cancers are usually linked to somatic mutations, which only happen in the lung cells affected by the cancer. When lung cancer is related to inherited genetic changes, the risk of cancer is passed down in an autosomal dominant pattern. This means that having just one copy of the changed gene in each cell is enough to raise a person's chance of getting the disease. It's important to remember that people inherit a greater chance of getting cancer, not the cancer itself. Therefore, not everyone who inherits changes in these genes will necessarily develop lung cancer.