Cancer is a disease that occurs when one or several genes mutate, forming cancerous cells. The cancerous cells grow unusually faster than normal cells, forming tumors or cancer clusters from which some cancerous cells might break away and spread throughout the body through the blood or lymphatic system. With more than 200 different types of the disease discovered, some of the most common ones are breast, lung, prostate, colorectal, and skin.

Breast cancer affects approximately 268,600 women and 2,670 men annually and is the most commonly diagnosed cancer in the United States and other countries. While it generally presents no symptoms during early stages, regular mammograms can help in early detection. The most common symptom is a lump in the breast. Still, other signs include nipple discharge, changes in nipple shape, unexplained swelling, redness, itchiness, skin irritation or rash on and around the breast, consistent breast pain, and changes in skin texture on the breast. Breast cancer can be non-invasive or invasive. Non-invasive has not spread to other parts and is usually called stage zero. An invasive type has spread to other tissues and is categorized as stage one, two, three, or four, depending on its extent. Depending on the affected tissues, it is also categorized as sarcoma, angiosarcoma, lobular carcinoma, or ductal carcinoma.

With 228,150 estimated new cases yearly, lung cancer is the second most common and the leading cause of cancer deaths. Cigarette smoking is the number one cause of lung cancer, and it can be either non-small cell or small cell lung cancer. Doctors usually group lung cancer into three progressive stages; localized, regional, or distant. Localized cancer is only present in one lung, regional has spread to the lymph nodes and other nearby body parts, and distant has spread to the other lung or other distant body parts like the liver, bones, or brain. Some symptoms include persistent cough, chest pain, fatigue, unexplained weight loss, wheezing, and coughing blood.

With around 164,690 new cases yearly and approximately 29,430 deaths, prostate cancer is the most common cancer among men. It is usually categorized as aggressive or non-aggressive, depending on how fast it grows and spreads. It is more common among men that are over 50 years old, have a family history of the disease, are obese, or are of African American descent. Some of the most common symptoms include frequent need to urinate, bleeding when urinating, slower or weaker urine streak, erectile dysfunction, and pain or numbness in the legs.

Colorectal cancer begins in the colon or rectum and has approximately 145,600 new annual cases. While it mostly happens in older people, it can happen at any age. Some common early symptoms include blood in stool, persistent changes in bowel habits like constipation or diarrhea, unexplained weight loss, persistent abdominal discomfort, and feeling like the bowels are not fully emptied.

Also known as melanoma, skin cancer has an estimated 96,480 new yearly cases. It starts in the cells that give the skin its color, called melanocytes, and can affect even the eyes. Some of the most common indications of the disease include large brownish spots with dark speckles, painful lesions that burn or itch, and small lesions with irregular borders or portions that are white, pink, red, or blue-black. Other indicators include moles that change in size or color and the presence of dark lesions on the soles, palms, or fingertips.