Cancer is an umbrella term for a large group of diseases caused when abnormal cells divide and invade other tissue and organs. Cancer is the second leading cause of death in the U.S., and more than 1.5 million Americans are diagnosed with some form of it every year. According to the American Cancer Society, half of all men and a third of all women in the U.S. will develop cancer in their lifetimes.
Cancer Growth and Metastasis
Healthy cells have a specific life cycle, reproducing and dying off in a way that is determined by the type of cell. But sometimes, because of abnormalities, the cells multiply out of control and also do not die off when they should. This process may result in growths called tumors, which in turn can cause a variety of symptoms, depending on where they grow.
However, not all tumors are cancerous. Benign tumors are noncancerous and do not spread to nearby tissues, though they can sometimes grow large and cause problems when they press against neighboring organs and tissue. Malignant tumors are cancerous, and they have the ability to invade other parts of the body.
Cancer cells can also migrate through the bloodstream or lymphatic system from the place they originally grew to distant areas of the body. This process is called metastasis. Cancers that have metastasized are considered more advanced than those that have not, and metastatic cancers tend to be harder to treat and more fatal.
Types of Cancer
Cancers are named for the area in which they begin, even if they spread to other parts of the body. For example, a cancer that begins in the lungs and spreads to the liver is still called lung cancer. There are also several clinical terms used for certain cancers:
Risk Factors & Treatment
Not all of the causes of cancer are known, but many things have been found to affect a person's risk for developing certain kinds of cancer.
Treatment depends on the type of cancer and how advanced it is, but the most common types are:
Quit Smoking
In addition to lung cancer, smoking tobacco is known to cause cancers of the mouth, throat, larynx, esophagus, stomach, pancreas, kidney, bladder, and cervix. Scientists estimate that 30 percent of all cancer deaths in the U.S. are due to smoking. Secondhand smoke, the smoke that nonsmokers are exposed to by being around smokers, is also known to increase the risk of cancer.
Although smokers who quit do not reduce their cancer risk to the level of someone who has never smoked, quitting still helps. According to the National Cancer Institute, people who stop smoking before age 30 have a 90 percent lower risk of dying due to smoking-related disease (such as lung cancer, emphysema, and chronic bronchitis), and those who quit before age 50 have a 50 percent lower risk.
Avoid Carcinogens
A carcinogen is a chemical known to cause cancer. Cigarette smoke, discussed above, contains more than 50 carcinogens. Other carcinogens include:
Ultraviolet (UV) radiation from the sun (and tanning beds) can damage the DNA of skin cells and cause skin cancer. When going out in the sun, always take precautions to protect yourself by wearing a hat, sunglasses, and clothing that covers most of your skin, or by applying sunscreen frequently. Learn more about UV rays, SPF, and the most affective sunscreens.
Other forms of radiation—such as high levels of radon (a radioactive gas) in your home and medical tests that use radiation (x-rays, CT scans)—can also cause cancer. To avoid unnecessary exposure to radiation, test your home for radon (find simple, inexpensive test kits at hardware stores), and avoid excessive x-rays and similar tests when possible.
Eat Healthy and Exercise
Studies have shown that a diet high in fat and red and processed meats increases the risk of colon, prostate, and other cancers. Excessive alcohol consumption—more than one drink per day for women and two per day for men—is also linked to cancers of the mouth, esophagus, and liver. On the other hand, a diet rich in fruits, vegetables, and whole grains has been found to decrease the risk of digestive system, lung, and other cancers.
Exercising regularly can also lower your cancer risk. Adults who get at least 2.5 hours of moderate intensity physical activity per week lower their risk of colon cancer by a third compared to those who do not exercise.
Obesity and Cancer
A combination of good food choices and exercise helps to achieve and maintain a healthy weight. These lifestyle habits help reduce the risk of cancer (and other diseases such as heart disease and diabetes). Studies have shown that being overweight or obese can increase your risk of breast, colon, esophageal, kidney, gallbladder, and uterine cancers.
Get Tested
Routine cancer tests do not prevent cancer from developing, but they do allow cancers to be detected early, which greatly improves a patient’s prognosis. The American Cancer Society recommends regular screenings for the following:
Breast Cancer
There has been a recent controversy regarding when women should begin regular screenings for breast cancer. The American Cancer Society (ACS) recommends annual mammograms starting at age 40. The U.S. Preventive Services Task Force (USPSTF) recommends that women between the ages of 50 and 74 years should have a screening mammogram every other year to check for breast cancer. Talk to your doctor about the right screening plan for you.
Cervical Cancer
The ACS recommends that women begin cervical cancer screening three years after their first vaginal intercourse but no later than 21 years of age, after which they should be screened every year if they are sexually active. Women between ages 30 and 65 whose previous pap smears have been normal should have the test done every three years.
Prostate Cancer
The ACS is less definitive about prostate cancer screening, stating that men should “make informed decisions with their doctor about whether to be tested.” This is due to the lack of research to prove that the potential benefits of screening outweigh the harms of testing and treatment. Men who are 50 years of age should discuss the pros and cons of screening. Those at a higher risk of prostate cancer—such as African-American men or men with a family history of prostate cancer—should start talk to their doctors at age 45.
Colorectal Cancer
There are several tests to screen for colorectal cancer and/or polyps. According to the ACS, women and men over the age of 50 should have an annual fecal occult blood test, which screens for cancer. Other recommended tests that screen for cancer and polyps include a flexible sigmoidoscopy (recommended every five years), a colonoscopy (every 10 years), a double-contrast barium enema (ever 5 years), or a CT colonography (every 5 years). Talk to your doctor about which tests and screening schedule is right for you.
Get Vaccinated
HPV
Some types of human papillomavirus (HPV) can infect the genital area; in fact, genital HPV is the most common sexually transmitted infection. Certain types of HPV can cause genital warts, while other types can cause cervical cancer. A vaccine against HPV called Gardasil has been approved by the FDA and is recommended for all girls and women between ages 9 and 26.
Hepatitis B
Hepatitis B virus causes inflammation of the liver, potentially resulting in serious liver disease including chronic infection, scarring, and cancer. According to the Centers for Disease Control and Prevention (CDC), children should get their first dose of the vaccine—usually given in a series of three or four shots—at birth and should have complete the vaccine by 6 to 18 months of age. It is recommended for anybody under age 18 who did not get the vaccine at birth and for unvaccinated adults at higher risk for the disease.
The vaccine is not recommended for anyone severely allergic to baker’s yeast or other components of the vaccine. Those are ill or who have had a previous severe allergic reaction to the vaccine should not be vaccinated.
There are a variety of symptoms that may indicate the presence of cancer. Unfortunately, other diseases can cause similar problems, so it’s important that you see a doctor if you are having problems with one or more of the symptoms below. Conversely, cancer may be present even in the absence of symptoms, so regular screenings are important for certain cancers.
Depending on the type of cancer, where it is located, how advanced it is, and whether it has spread to multiple areas of the body, doctors will choose one or a combination of the treatments below. These treatments can be used as primary therapy (used to kill existing cancer cells) or as adjuvant therapy (used to prevent cancer from coming back).
Surgery
The goal of surgery is to remove all or most of the cancerous tumor(s). Surgery is a very common cancer treatment, but it cannot be used in all cases. For example, cancers of the blood, such as leukemia, do not form tumors. Some tumors may be inoperable because they have grown into or are very close to vital organs. Cancer that has metastasized throughout the body cannot be treated with surgery.
The side effects of cancer surgery are the same as any other kind of surgery and include pain and possible infection. In addition, surgery may damage nearby organs or other important tissue, causing a range of problems.
Chemotherapy
Chemotherapy uses powerful drugs to kill cancer cells. It is usually given in cycles where the patient is treated for several days and then has a recovery period before another cycle of treatment. There are dozens of chemotherapy drugs, each with its own set of side effects, but the most common side effects are hair loss, nausea, vomiting, diarrhea, weakness, fatigue, and a weakened immune system.
Radiation therapy
Radiation therapy is the use of concentrated radiation to kill cancer cells. While chemotherapy affects the entire body, radiation is usually targeted to specific areas, either by implanting radioactive materials in the body or by using computerized machines that control beams of radiation to deliver a very specific dose. Common side effects of radiation therapy are nausea, vomiting, skin sensitivity or burns, and fatigue.
Other Cancer Treatments
Surgery, chemotherapy, and radiation therapy are the most common treatment types, but other options may be available:
Cancer Growth and Metastasis
Healthy cells have a specific life cycle, reproducing and dying off in a way that is determined by the type of cell. But sometimes, because of abnormalities, the cells multiply out of control and also do not die off when they should. This process may result in growths called tumors, which in turn can cause a variety of symptoms, depending on where they grow.
However, not all tumors are cancerous. Benign tumors are noncancerous and do not spread to nearby tissues, though they can sometimes grow large and cause problems when they press against neighboring organs and tissue. Malignant tumors are cancerous, and they have the ability to invade other parts of the body.
Cancer cells can also migrate through the bloodstream or lymphatic system from the place they originally grew to distant areas of the body. This process is called metastasis. Cancers that have metastasized are considered more advanced than those that have not, and metastatic cancers tend to be harder to treat and more fatal.
Types of Cancer
Cancers are named for the area in which they begin, even if they spread to other parts of the body. For example, a cancer that begins in the lungs and spreads to the liver is still called lung cancer. There are also several clinical terms used for certain cancers:
- Carcinoma is a cancer that starts in the skin or the tissues that line other organs.Sarcoma is
- a cancer of connective tissues such as bones, muscles, cartilage, and blood vessels.
- Leukemia is a cancer of bone marrow, which creates blood cells.
- Lymphoma and myeloma are cancers of the immune system.
Risk Factors & Treatment
Not all of the causes of cancer are known, but many things have been found to affect a person's risk for developing certain kinds of cancer.
- Diet
- Exposure to chemicals
- Unprotected exposure to the sun
- Genetics
- Certain viruses, such as HPV
- Smoking
Treatment depends on the type of cancer and how advanced it is, but the most common types are:
- Surgery to remove tumors
- Chemotherapy (the use of toxic medications to kill cancer cells)
- Radiation therapy (the use of focused beams of radiation to kill cancer cells)
Quit Smoking
In addition to lung cancer, smoking tobacco is known to cause cancers of the mouth, throat, larynx, esophagus, stomach, pancreas, kidney, bladder, and cervix. Scientists estimate that 30 percent of all cancer deaths in the U.S. are due to smoking. Secondhand smoke, the smoke that nonsmokers are exposed to by being around smokers, is also known to increase the risk of cancer.
Although smokers who quit do not reduce their cancer risk to the level of someone who has never smoked, quitting still helps. According to the National Cancer Institute, people who stop smoking before age 30 have a 90 percent lower risk of dying due to smoking-related disease (such as lung cancer, emphysema, and chronic bronchitis), and those who quit before age 50 have a 50 percent lower risk.
Avoid Carcinogens
A carcinogen is a chemical known to cause cancer. Cigarette smoke, discussed above, contains more than 50 carcinogens. Other carcinogens include:
- Asbestos
- Benzene
- Cadmium
- Nickel
- Radon
- Uranium
- Vinyl chloride
Ultraviolet (UV) radiation from the sun (and tanning beds) can damage the DNA of skin cells and cause skin cancer. When going out in the sun, always take precautions to protect yourself by wearing a hat, sunglasses, and clothing that covers most of your skin, or by applying sunscreen frequently. Learn more about UV rays, SPF, and the most affective sunscreens.
Other forms of radiation—such as high levels of radon (a radioactive gas) in your home and medical tests that use radiation (x-rays, CT scans)—can also cause cancer. To avoid unnecessary exposure to radiation, test your home for radon (find simple, inexpensive test kits at hardware stores), and avoid excessive x-rays and similar tests when possible.
Eat Healthy and Exercise
Studies have shown that a diet high in fat and red and processed meats increases the risk of colon, prostate, and other cancers. Excessive alcohol consumption—more than one drink per day for women and two per day for men—is also linked to cancers of the mouth, esophagus, and liver. On the other hand, a diet rich in fruits, vegetables, and whole grains has been found to decrease the risk of digestive system, lung, and other cancers.
Exercising regularly can also lower your cancer risk. Adults who get at least 2.5 hours of moderate intensity physical activity per week lower their risk of colon cancer by a third compared to those who do not exercise.
Obesity and Cancer
A combination of good food choices and exercise helps to achieve and maintain a healthy weight. These lifestyle habits help reduce the risk of cancer (and other diseases such as heart disease and diabetes). Studies have shown that being overweight or obese can increase your risk of breast, colon, esophageal, kidney, gallbladder, and uterine cancers.
Get Tested
Routine cancer tests do not prevent cancer from developing, but they do allow cancers to be detected early, which greatly improves a patient’s prognosis. The American Cancer Society recommends regular screenings for the following:
Breast Cancer
There has been a recent controversy regarding when women should begin regular screenings for breast cancer. The American Cancer Society (ACS) recommends annual mammograms starting at age 40. The U.S. Preventive Services Task Force (USPSTF) recommends that women between the ages of 50 and 74 years should have a screening mammogram every other year to check for breast cancer. Talk to your doctor about the right screening plan for you.
Cervical Cancer
The ACS recommends that women begin cervical cancer screening three years after their first vaginal intercourse but no later than 21 years of age, after which they should be screened every year if they are sexually active. Women between ages 30 and 65 whose previous pap smears have been normal should have the test done every three years.
Prostate Cancer
The ACS is less definitive about prostate cancer screening, stating that men should “make informed decisions with their doctor about whether to be tested.” This is due to the lack of research to prove that the potential benefits of screening outweigh the harms of testing and treatment. Men who are 50 years of age should discuss the pros and cons of screening. Those at a higher risk of prostate cancer—such as African-American men or men with a family history of prostate cancer—should start talk to their doctors at age 45.
Colorectal Cancer
There are several tests to screen for colorectal cancer and/or polyps. According to the ACS, women and men over the age of 50 should have an annual fecal occult blood test, which screens for cancer. Other recommended tests that screen for cancer and polyps include a flexible sigmoidoscopy (recommended every five years), a colonoscopy (every 10 years), a double-contrast barium enema (ever 5 years), or a CT colonography (every 5 years). Talk to your doctor about which tests and screening schedule is right for you.
Get Vaccinated
HPV
Some types of human papillomavirus (HPV) can infect the genital area; in fact, genital HPV is the most common sexually transmitted infection. Certain types of HPV can cause genital warts, while other types can cause cervical cancer. A vaccine against HPV called Gardasil has been approved by the FDA and is recommended for all girls and women between ages 9 and 26.
Hepatitis B
Hepatitis B virus causes inflammation of the liver, potentially resulting in serious liver disease including chronic infection, scarring, and cancer. According to the Centers for Disease Control and Prevention (CDC), children should get their first dose of the vaccine—usually given in a series of three or four shots—at birth and should have complete the vaccine by 6 to 18 months of age. It is recommended for anybody under age 18 who did not get the vaccine at birth and for unvaccinated adults at higher risk for the disease.
The vaccine is not recommended for anyone severely allergic to baker’s yeast or other components of the vaccine. Those are ill or who have had a previous severe allergic reaction to the vaccine should not be vaccinated.
There are a variety of symptoms that may indicate the presence of cancer. Unfortunately, other diseases can cause similar problems, so it’s important that you see a doctor if you are having problems with one or more of the symptoms below. Conversely, cancer may be present even in the absence of symptoms, so regular screenings are important for certain cancers.
- Pain
- A lump under the skin
- A new mole or a mole that changes size, or a lesion that doesn’t heal
- Hoarseness
- A cough that doesn't go away, coughing up blood, or shortness of breath
- Trouble swallowing or pain/heartburn after eating
- Changes in bowel or bladder habits, or blood in the stool or urine
- Unexplained weight gain or loss
- Enlarged lymph nodes
- Neurologic symptoms such as tingling sensations, changes in vision, or seizures
- Extreme weakness or fatigue
- Depression
Depending on the type of cancer, where it is located, how advanced it is, and whether it has spread to multiple areas of the body, doctors will choose one or a combination of the treatments below. These treatments can be used as primary therapy (used to kill existing cancer cells) or as adjuvant therapy (used to prevent cancer from coming back).
Surgery
The goal of surgery is to remove all or most of the cancerous tumor(s). Surgery is a very common cancer treatment, but it cannot be used in all cases. For example, cancers of the blood, such as leukemia, do not form tumors. Some tumors may be inoperable because they have grown into or are very close to vital organs. Cancer that has metastasized throughout the body cannot be treated with surgery.
The side effects of cancer surgery are the same as any other kind of surgery and include pain and possible infection. In addition, surgery may damage nearby organs or other important tissue, causing a range of problems.
Chemotherapy
Chemotherapy uses powerful drugs to kill cancer cells. It is usually given in cycles where the patient is treated for several days and then has a recovery period before another cycle of treatment. There are dozens of chemotherapy drugs, each with its own set of side effects, but the most common side effects are hair loss, nausea, vomiting, diarrhea, weakness, fatigue, and a weakened immune system.
Radiation therapy
Radiation therapy is the use of concentrated radiation to kill cancer cells. While chemotherapy affects the entire body, radiation is usually targeted to specific areas, either by implanting radioactive materials in the body or by using computerized machines that control beams of radiation to deliver a very specific dose. Common side effects of radiation therapy are nausea, vomiting, skin sensitivity or burns, and fatigue.
Other Cancer Treatments
Surgery, chemotherapy, and radiation therapy are the most common treatment types, but other options may be available:
- Hormone therapy uses drugs and surgery to reduce levels of hormones that make certain kinds of cancers grow, especially breast and prostate cancers.
- Biological therapy (or immunotherapy) attempts to train the body's own immune system to recognize and fight cancer cells.
- Gene therapy attempts to alter the DNA of cancer cells, either to return them to normal or to make them more susceptible to other types of treatment.
- Palliative care focuses on improving overall quality of life for patients and families facing serious illness. Recent research has found that cancer patients receiving palliative care had a better quality life and lived longer than those who only received standard treatment.
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