Cancer is the second deadliest disease in America, behind heart disease—but the term "cancer" actually lumps over 100 diseases into one. All cancers have a lot in common: Mutations make cells change and grow out of control, and are often caused by some combination of genetic and environmental factors. Most people differentiate types of cancer by where they appear in the body, such as breast cancer or prostate cancer.
But there's another way to group types of cancer: Not just by where they appear, but what kind of cells they attack. This breaks the disease into several common types of cancer: Carcinoma, sarcoma, melanoma, lymphoma, and leukemia. Learning how cancer works can give you a better understanding of the disease—that's important because cancer will strike one in three people.
"This is a type of cancer that starts in the cells that make up the skin or the tissues that line organs—these are the most common cancers," says oncologist Larry Norton, MD, of Memorial Sloan Kettering Cancer Center. Carcinomas account for 80 to 90 percent of cancers, according to the National Cancer Institute. "Examples are breast cancer, lung cancer, prostate cancer, and kidney cancer," Dr. Norton says. People often get carcinomas in organs or glands: You might have heard "carcinoma" used with renal cell carcinoma (kidney cancer), papillary carcinoma (thyroid cancer), or invasive ductal carcinoma (breast cancer).
Although all of these cancers are different, they have similarities: "Certain factors significantly increase one's risk of getting cancer: Tobacco use is the most common cause, but obesity is not far behind," Dr. Norton says. Here are 37 lifestyle changes you can make to reduce your risk of cancer.
One undeniable—and unavoidable—risk is simply getting older, and because carcinomas are the most common type of cancer, they're also responsible for the most cancer deaths. While the symptoms will be different depending on where the cancer turns up, carcinomas do form solid tumors and you might first notice one as a lump. Basal cell carcinoma and squamous cell carcinoma of the skin look like strange red patches, bumps, sores, or growths on the skin. "Symptoms depend on the organ that is involved and the stage of the disease; early on, most cancers do not cause symptoms," Dr. Norton says. "This is why screening is often important."
Today, there are more cancer treatments than ever before, says Dr. Norton, but they have to be tailored for each patient. The major treatments include surgery to remove the tumor, radiation therapy to kill cancer cells, drug therapies—including chemotherapy—that kill rapidly dividing cells, and targeted therapies that can kill cancers with certain mutations, hormonal drugs (particularly useful with breast cancer), and immunotherapy, which unleashes the body's own ability to identify and kill cancer cells.
This is less common than carcinoma and other types of cancer. "Sarcoma starts in the cells that make up the connective tissues, under or between the tissues that line organs," Dr. Norton says. "Examples are cancers of the fat, muscle, and blood vessels." Sarcomas are broken down into two main groups: bone sarcoma and soft-tissue sarcoma.
Unfortunately, osteosarcoma, the most common type of bone sarcoma, most often occurs in children and teens. Because it targets young people, researchers don't believe lifestyle factors influence risk; rather, the cancer may be spurred by the rapid growth children experience. People who have had certain bone conditions or syndromes—or who've undergone radiation treatment—might also be at greater risk. Osteosarcoma affects males slightly more, and it's a bit more common in African-Americans and Latinos than whites. One of the most common symptoms of osteosarcoma is pain in a limb, but because kids often get bumps and bruises, doctors can miss the diagnosis. Learn more about surprising symptoms that turn out to be cancer.
There are more than 50 types of soft-tissue sarcoma; some are more common in children, others hit adults more often. The sarcomas can start in the arm or leg, but may also affect the trunk, head, or the back of the abdomen. Doctors don't know what the risk factors are for these diseases—lifestyle doesn't seem to play a role. Having been treated with radiation or testing positive for certain genetic syndromes may pose a risk, but there's nothing you can really do to prevent this disease. The symptoms will vary depending on where a tumor turns up, but they can include a lump on the affected limb, abdominal pain, black or bloody stool, or trouble breathing.
As with other cancers, treatments for sarcomas include surgery, radiation, and chemotherapy; recent research has shown promise for certain immunotherapies for sarcomas as well.
Melanoma is one of the easier types of cancer to spot, as it usually only shows up on your skin. "Melanoma is a type of cancer that starts in skin cells that contain pigment," Dr. Norton says. "This is why they are often dark or black." This is the deadliest type of skin cancer: Although it's rarer than basal cell or squamous cell carcinoma of the skin, melanoma is more likely to grow and spread. It's also responsible for the most skin cancer deaths.
According to the American Cancer Society, most cases of melanoma could be preventable. "Excessive sun exposure is the biggest risk factor for melanoma," Dr. Norton says. In other words, avoid tanning beds, cover up when you're outdoors, and wear your sunscreen—these are the best types of sunscreen. Caucasian people tend to get melanoma more often due to their light skin, which is more susceptible to the sun's damaging UV rays. Although melanoma is more likely in older people, it's still one of the most common cancers in the under-30 crowd. Before age 50, melanoma is more common in women, but by age 65, twice as many men get melanoma compared to women; by age 80 men have triple the rate of women. Overall, melanoma is the sixth most common cancer.
Surgery alone can cure melanoma if doctors catch it early. Among the 51 things dermatologists need you to know about skin cancer, perhaps most important is checking yourself regularly using the ABCDEs: Look for moles that are asymmetrical, have an irregular border, contain different colors, are larger in diameter than a pencil eraser, and evolve in size, shape, or color. If you notice anything strange, make an appointment with a dermatologist. If melanoma has spread, treatment may also require chemo, radiation, or targeted therapies.
The last two types of cancers both involve the blood. "Lymphoma and leukemia are types of cancers that start in white blood cells," Dr. Norton says. Lymphoma attacks lymphocytes, a type of white blood cell that fights infections. They're part of the lymphatic system, which includes lymph nodes and the spleen.
Unlike leukemia, "lymphomas form solid masses," Dr. Norton says. Lymphoma is divided into two main types: Hodgkin's lymphoma and non-Hodgkin's lymphoma. Hodgkin's is much less common and it's characterized by the presence of certain abnormal cells called Reed-Sternberg cells. It can occur in both children and adults but is most common in young adults between 15 and 35 years old, as well as older adults. It's also the most common cancer in teens between the ages of 15 and 19. The main risk factors—altered immune function due to autoimmune disorders, certain infections, and immune suppressant medications (taken after organ transplants)—can't really be prevented.
Non-Hodgkin's lymphoma, one of the most common types of cancer in the United States, most often happens in older adults, although children can get it, too. Obesity may play a part in some cases, but its main risk factors are similar to Hodgkin's. Symptoms for both types include swollen lymph nodes in the neck, groin, or armpit, fever, fatigue, and loss of appetite—it may feel like you have a cold that doesn't go away. Lymphoma is also one of the unexpected explanations for night sweats. Surgery is not usually an option—treatments include chemo, radiation, stem cell transplants, immunotherapy, or other targeted therapy.
Because leukemia doesn't form solid tumors, it's considered a "liquid" cancer. "Leukemias involve the bone marrow and also float freely in the blood," Dr. Norton says. Leukemia sub-types affect different types of blood cells. Although most cases are in adults, leukemias are also the most common types of cancer that children get: About 30 percent of childhood cancers are leukemia. Smoking is a risk factor in adults—there is some evidence that parental smoking before and after birth may increase the risk in children. Obesity may also be a risk for some leukemias; radiation and exposure to certain chemicals may also increase risk. But usually, there's not much you can do to prevent leukemia.
Symptoms may include fatigue, pale skin, weight loss, fever, bruising or bleeding easily, bone pain, and infections. As with lymphoma, chemo, radiation, stem cell transplant, and targeted therapies may be used for treatment. In a recent breakthrough, researchers have found that CAR T-cell therapy is particularly effective for certain difficult-to-treat leukemias. Read about this and other groundbreaking cancer discoveries.