Cancer is a broad term used to describe many different diseases. In general, cancer happens when abnormal cells in your body grow out of control and crowd out normal cells.
It can start almost anywhere. Cancer can stay in one spot, or it can metastasize — spread throughout your body. Some cancers grow slowly, while others grow quickly.
Most cancers are named for where they start in the body. For instance, “breast cancer” begins in your breast tissue.
Many cancers form solid tumors, which are growths of tissue. But blood cancers, such as leukemia, don’t generally grow as tumors; they stay in the form of individual cells. Tumors can be either malignant (cancerous) or benign (noncancerous).
Prevalence: Cancer Is a Common Disease
According to the National Cancer Institute, more than 1.6 million new cases of cancer are diagnosed in the United States each year. About 597,690 people die from some form of the disease annually. (1)
Data also shows that more than 38 percent of men and women will be diagnosed with a form of cancer at some point in their lives. (2)
Cancer is the second-leading cause of death in this country, after heart disease. (3)
Anyone can get cancer, but the risk goes up as you get older. Nearly 9 out of 10 cancers are diagnosed in people 50 years of age or older. (4)
The good news is that survival rates are improving for many types of cancer because of advances in screening and treatment.
The Gene Factor: How Cancer Happens
Cancer is a genetic disease, which means it’s caused by changes in genes that control the way cells grow and divide in your body.
These gene alterations, sometimes called “mutations” cause a variety of changes that can make a cell cancerous. Some mutations accelerate the pace at which a cell duplicates itself, others prevent cells from knowing when to stop dividing, and still others keep them from dying off as normal cells are supposed to do. When a cell has acquired enough of these mutations to interfere with the “rules” by which normal cells behave, it has become cancerous.
Mutations can be inherited at birth or acquired during your lifetime. Exposure to harmful substances, such as tobacco smoke or radiation, can damage your DNA and cause gene changes to occur. Other lifestyle factors, such as extensive sun exposure, can also lead to mutations.
Just because you’re born with a certain mutation doesn’t always guarantee that you’ll develop cancer. Only 5 to 10 percent of cancers are a direct result of a mutation inherited from a parent. (5) Usually, inherited and acquired mutations work together to cause cancer. For example, you might inherit a gene from your parents that makes you more likely to develop a certain type of cancer when you’re exposed to tobacco smoke.
Metastasis: When Cancer Spreads
Cancer can spread from the area it started to other places in your body. This is known as metastasis.
Metastatic cancer can affect many organs of your body, but it still has the same type of cancer cells as the original cancer. Doctors will name your cancer based on its primary location. So, pancreatic cancer that has spread to your liver is still known as pancreatic cancer.
Generally, metastatic cancer cells look the same as the cells of the original cancer when viewed under a microscope.
When cancer spreads, it becomes much harder for doctors to treat.
The Most Common Cancers Affecting Americans
Nonmelanoma skin cancer is the most common form of cancer, affecting about 3.3 million people in the United States each year. (6)
Breast cancer is next, followed by lung cancer and prostate cancer.
Other common cancers include:
- Colon and rectal cancer
- Liver cancer
- Bladder cancer
- Endometrial cancer
- Kidney cancer
- Non-Hodgkin lymphoma
- Pancreatic cancer
- Thyroid cancer
Cancers Start in a Variety of Different Tissues in the Body
Cancer can happen anywhere in your body. There are many types of cancers, and each type also has its own subtypes that doctors may approach differently.
Cancers are sometimes divided into categories, including the following:
Carcinomas These are the most common types. They’re formed by epithelial cells, which line the inside and outside surfaces of the body. Carcinomas can be divided into the following subcategories:
- Adenocarcinomas develop in epithelial cells that make fluids or mucus. Breast, colon, and prostate cancers are adenocarcinomas.
- Basal cell carcinomas start in the lower base layer of the skin.
- Squamous cell carcinomas form in epithelial cells that are just below the outer surface of the skin. Squamous cells also line organs, such as the intestines, stomach, bladder, lungs, and kidneys.
- Transitional cell carcinomas form in a type of tissue called transitional epithelium. Cancers of the bladder, ureters, or kidneys are sometimes transitional cell carcinomas.
Sarcomas Sarcomas form in the bone and soft tissues (muscles, blood vessels, fat, tendons, ligaments, or lymph vessels) of the body. Osteosarcoma is a common type of bone cancer. Soft-tissue sarcomas include Kaposi sarcoma, liposarcoma, and others.
Leukemias Cancers that begin in the blood-forming cells are leukemias. They don’t usually form tumors, but instead grow in blood and bone marrow.
Lymphomas Lymphomas are cancers that develop from normal lymphocytes, which are infection-fighting white blood cells that are part of your immune system. Hodgkin lymphoma and non-Hodgkin lymphoma are the two main types.
Melanomas These cancers begin in cells called melanocytes, which give your skin its color. Most of the time, melanomas form on the skin, but they can also develop in other areas, such as the eye.
Multiple myelomas Multiple myeloma is a type of blood cancer that is derived from plasma cells, which are a type of immune cell.
Brain and spinal cord tumors: These tumors form in the nervous system of the body.
Neuroendocrine tumors They develop in cells that release hormones into your blood.
Carcinoid tumors These are a type of neuroendocrine tumor that are usually found in the rectum and small intestine.
Germ cell tumors Germ cell tumors begin in the reproductive cells (egg or sperm) of your body.
Life With Cancer
Years ago, people with cancer didn’t survive long. Thanks to medical advances, the outlook has improved significantly in recent years.
Today, about 15 million people in the United States are living with cancer. (4)
In recent years, cancer awareness movements have brought attention to all different types of cancers. You may have seen or worn a cancer ribbon to support yourself or a loved one as part of a cancer campaign. These programs help raise much-needed funds for research and drug development.
What Are the Risk Factors for Cancer?
6 Things That Happen to Your Body—and Your Risk for Lung Cancer—When You Stop Smoking.
Cancer is not one disease, but many. Each requires its own special care and its particular treatment strategy. But one thing about cancer is easy to understand: you are far better off not getting it in the first place.
How do you do that? By avoiding the risks. Doctors understand a good deal about what can cause cancer, and you should stay far away from those causes. First among them is smoking. It is a primary cause of lung cancer and of more than a dozen other cancers. And there are other causes: unhealthy diets, obesity, lack of exercise, excess alcohol, and sun exposure among others. Know and avoid the risk factors, and you can help prevent cancer.
Learn More About Cancer Risk and Prevention
What Are the Signs and Symptoms of Cancer?
Knowing the signs and symptoms of cancer can help you and your doctor make a speedy diagnosis so that the cancer can be treated early. And that can boost the chances that the treatment will be successful.
Indications of cancer include such things as unexplained weight loss, fever and night sweats, extreme fatigue, and unexplained bleeding. None of these signs should cause immediate concern; they don’t always mean you have cancer. Some of them can be caused by entirely unrelated ailments. But the more you know, and the sooner you see your doctor, the more likely you and your doctor can spot cancer indications and start treatment.
Learn More About Cancer Signs and Symptoms
What Tests Are Used to Diagnose Cancer?
If you turn up with positive results on a screening test, don’t panic! For some cancers, doctors have good diagnostic tools that can go beyond screening and tell you whether you do or do not have cancer.
Imaging is one common tool used to confirm suspicious findings during cancer screening, including CT scans, X-rays, MRIs, and mammograms, among others. Another is what’s known as endoscopy, in which doctors insert a tube into the body to take a careful look around and see if they can spot any tumors. And a third tool is the biopsy, in which doctors take a small sample of your tissue to look for cancer. Some of the tests are more accurate than others, but all of them can help make a diagnosis.
Learn More About Cancer Tests and Diagnosis
A Cancer's Stage Will Guide Its Treatment
When cancer is diagnosed, you and your doctor are going to want to know how far the cancer has progressed. Did a diagnostic tool catch it early? Or is it at a late stage in which, perhaps, it has already started to spread throughout the body?
Stage 1 means cancer is present. Stage 2 and stage 3 mean the tumor has grown and started to spread into nearby tissues. Generally, stage 4 means it has spread to distant parts of the body. Each type of cancer has a distinct staging system, and interpreting cancer staging can be tricky. Your oncologist can explain what your stages mean.
Learn More About Cancer Stages
There's an Arsenal of Weapons to Treat Cancer
Oncologists have a broad and growing selection of treatments they can now use to fight cancer. Many cancer patients can expect to receive a combination of treatments, depending on the kind of cancer they have and what stage it is at.
Surgery can be used to cut out tumors, and chemotherapy and radiation can be used to kill cancer cells; sometimes patients receive all three of these treatment approaches.
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Immunotherapy is a newer treatment option in which the therapy increases the ability of the body’s immune cells to better recognize and attack cancer cells. Another newer treatment is targeted therapy, in which doctors directly attack genes or chemical pathways that spur cancer growth. New immunotherapies and targeted therapies are being developed every year.
Learn More About Cancer Treatment
Palliative Care Can Help Ease Discomfort
On Chemo Brain and Dropped Words
As anyone who has undergone cancer treatment can tell you, the therapy can often be tough to endure, and can sometimes cause dangerous side effects. Treating those symptoms can improve the lives of patients while they and their doctors are trying to get rid of their cancer. Such treatment is referred to as palliative care, or supportive care. The treatments include medication, emotional support, relaxation techniques, nutritional support, and more. This kind of care can be important for children, too, as well as adults.
Learn More About Palliative Care
Cancer Resources We Love
If you’ve been given a cancer diagnosis, certain resources can help you better understand and cope with your condition. Here’s a collection of some of our favorite organizations, articles, and websites for more information and support.
Favorite Cancer Organizations
American Cancer Society (ACS)
The ACS was founded in 1913 by 10 doctors and five laypeople determined to raise awareness about cancer. Since then, its mission has expanded to include providing education, support, services, advocacy, and funding.
National Cancer Institute (NCI)
The NCI is the hub of government-funded cancer research in the United States. On its site, you’ll find information about specific types of cancer, ongoing research, and clinical trials.
American Society of Clinical Oncology (ASCO)
ASCO is an organization that represents physicians and oncology professionals who care for people with cancer. It aims to advance the care of patients through clinical research, policy, and educational resources.
American Association for Cancer Research (AACR)
The AACR is the world’s oldest professional organization dedicated to cancer research. It works to promote cancer awareness through education, research, and its publications.
National Comprehensive Cancer Network
This not-for-profit organization is an alliance of 27 comprehensive cancer centers committed to improving the research, education, and efficiency of high-quality cancer care.
American Childhood Cancer Organization (ACCO)
Formed by a group of parents whose children had cancer, the ACCO is now one of the largest grassroots organizations committed to the fight against childhood cancer. It provides support and assistance to families while offering programs to improve the lives of kids with cancer.
Gateway for Cancer Research
The Gateway is a nonprofit organization that funds cancer research and clinical trials worldwide. Ninety-nine cents of every dollar Gateway receives goes directly to fund phase 1 and phase 2 cancer clinical trials, which investigate the safety and efficacy of new treatments.
Favorite Online Support and Advocacy Networks
If you’re looking for support, CancerCare is a good place to start. The organization provides free services to anyone affected by cancer. It offers information about financial assistance and support from oncology social workers and cancer experts.
Cancer Support Community (CSC)
The CSC uses direct service delivery, research, and advocacy to ensure that everyone affected by cancer lives a better life. We love their Cancer Experience Registry — a place where patients, survivors, and caregivers can make their voices heard.
National Coalition for Cancer Survivorship (NCCS)
The NCCS advocates for quality cancer care. The nonprofit coined the widely accepted definition of survivorship and defines someone as a cancer survivor “from the time of diagnosis and for the balance of life.”
Sometimes, younger people with cancer feel overlooked. Stupid Cancer fills the gap for young adult (ages 15 to 39) cancer advocacy, research, and support. Its mission is to make sure that the young cancer community has age-appropriate information and resources.
Cancer Hope Network (CHN)
The CHN is a nonprofit organization that matches cancer patients, survivors, and their families with trained support volunteers for free. We love that the volunteers are cancer survivors who help and support patients through diagnosis, treatment, and recovery.
Friend for Life Cancer Support Network
Everyone who battles cancer needs a friend to lean on. Friend for Life matches cancer patients with trained volunteers to support them through treatment. The volunteers are cancer survivors themselves who had the same kind of cancer or went through the same course of treatment.
Patient Power provides resources for cancer patients so they can make informed decisions about their health and care. It connects you with a community of survivors, medical professionals, and organizations through its website and events.
Patient Advocate Foundation (PAF)
Navigating finances is difficult for many people with cancer. PAF acts as a liaison between a patient and their employer, insurer, and creditors. With the help of skilled case managers, patients get access to quality care and financial assistance.
Cancer Financial Assistance Coalition
The CFAC aims to help cancer patients manage their financial challenges. It’s a coalition of financial assistance organizations that have joined forces to help cancer patients experience better health and well-being by overcoming financial challenges.
RELATED: Is an Advanced Breast Cancer Support Group for You?
Favorite Apps, Products, and Gadgets
From ribbons to apparel, Choose Hope offers a variety of cancer awareness merchandise and gifts for anyone touched by cancer. You can search and purchase products based on cancer type. The best part is that the organization uses some of its proceeds to make a monthly corporate donation to a leading cancer research facility.
Just Don’t Send Flowers
Looking for the perfect gift for someone battling cancer? Just Don’t Send Flowers provides practical and personal options. Their chemo baskets and cancer care packages are loaded with thoughtful items for people being treated for cancer. You can even customize your gift with colors or ribbons to match a specific cancer type.
This free app is designed to help users manage life with cancer. It lets you connect with loved ones, ask for support, stay organized, and keep track of your health goals, all in one place. We like that you can invite friends and loved ones to support you and see your updates.
My Cancer Coach App
The free My Cancer Coach app offers information about personalized breast, prostate, and colon cancer treatment options. Some of the top features include questionnaires and treatment reports, videos, a calendar, a journal, and a glossary of common terms.
This free app, sponsored by ASCO, includes features that allow you to get up-to-date information on more than 120 types of cancer, track your treatments, log medication, and receive advice on how to manage side effects. You’ll also be able to access cancer-related podcasts, videos, and blogs. We love that the app is also available for Spanish speakers.
RELATED: How to Track the Side Effects of Your Chemo Treatment?
Favorite Cancer Blogs
Cancer Blog Community
Looking for a place to share your story? Blog for a Cure lets cancer patients document their journey. The free service is a way for the community to support each other and share their experiences and tips.
IHadCancer is a community of cancer survivors helping patients and their caregivers move forward in their cancer journey. Their blog page offers personal stories about living with and beating cancer.
Inspirational Cancer Blogs is a directory of blogs arranged according to cancer type.
Information is power when it comes to fighting cancer. The OncoLink blog provides up-to-date cancer information for patients, caregivers, and practitioners. It aims to empower patients with the right information so that they can be their own advocate and make informed treatment decisions.
RELATED: 10 Metastatic Breast Cancer Blogs to Read When You Feel Like No One Understands
Favorite Patient-Centered Annual Meetings
Patient-Centered Oncology Care Meeting
At this meeting, industry-leading experts collaborate on ways to improve value-based care. Patient-centered cancer care is the main topic covered.
American Association for Cancer Research (AACR) Meeting
The AACR Annual Meeting features the latest discoveries in cancer research. It highlights the work of the best minds from institutions around the world.
RELATED: Cancer News Highlights From the ASTRO Meeting
Favorite Information on Nutrition for Cancer
NCI’s Nutrition in Cancer Care
The NCI’s Nutrition in Cancer Care page provides a comprehensive overview that covers the role of nutrition for cancer patients. We like that the site highlights popular supplements and the studies that support their use.
RELATED: Diet and Cancer: What You Need to Know — and Eat — to Feel Your Best While Fighting Cancer
Commonweal Cancer Help Program (CCHP)
CCHP is a weeklong retreat located on a 60-acre site in California. The goal is to help attendees live better, and when possible, longer lives. The program includes daily group support sessions, massage, yoga, meditation, deep relaxation, imagery work, symbolic learning through a practice called Sandtray, poetry, and other healing exercises. CCHP is for people at any stage in the cancer journey and their significant others. The all-inclusive cost is around $2,500 a person.
Editorial Sources and Fact-Checking
- Cancer Statistics. National Cancer Institute. March 22, 2017.
- Cancer Stat Facts: Cancer of Any Site. National Cancer Institute.
- Cancer Overview. Mayo Clinic. May 23, 2015.
- Questions People Ask About Cancer. American Cancer Society. January 4,2018.
- Family Cancer Syndromes. American Cancer Society. January 4, 2018.
- Skin Cancer Facts & Statistics. Skin Cancer Foundation. January 31, 2018.
- What Is Cancer? American Cancer Society. December 8, 2015.
- What Is Cancer? National Cancer Institute. February 9, 2015.
- Cancer. MedlinePlus. January 19, 2018.
- Common Cancer Types. National Cancer Institute. February 13, 2017.