Cancer is not just one disease but many diseases. Cancer begins in your cells, which are the building blocks of your body. Usually, your body forms new cells as needed, replacing old cells that die. Sometimes this process goes wrong. New cells grow even when you don't need them, and old cells don't die when they should. These extra cells can form a mass called a tumor.

Tumors can be benign or malignant. Benign tumors aren't cancer, while malignant ones are. Cells from malignant tumors can invade nearby tissues. They can also break away and spread to other parts of your body. The spread of cancer from one part of the body to another is called metastasis. Symptoms and treatment depend on the type of cancer and how advanced it is.

There are more than 100 different types of cancer. Cancer can start almost anywhere in your body. Most cancers are named for where they start. For example, lung cancer starts in the lung, and breast cancer starts in the breast.

Cancer may also be described by the type of cell that formed it, such as sarcoma if cancer begins in your bone and soft tissue. Carcinoma is the most common type of cancer. It is formed by epithelial cells, the cells that cover the inside and outside surfaces of your body.

Cancer is a genetic disease. That means changes in your genes cause it. Changes in your genes are also called gene variants or mutations. Genes are parts of DNA in your cells that you inherit from your parents. However, only some cancers are caused by genes passed down from your parents.

Genetic changes can occur to your genes over your lifetime that affect how your cells function. Usually, your body gets rid of damaged cells before they turn cancerous, but this ability goes down as you age. Other factors that may affect your risk of developing cancer can include:

• Exposure to ultraviolet (UV) rays from the sun
• Smoking
• Your diet
• Physical inactivity

Cancer symptoms depend on the type of cancer. For example, some of the symptoms that cancer may cause can include:

• A lump in your breast
• Blood in your urine (pee) or stool (poop)
• Bleeding or bruising for no known reason
• A sore that doesn't heal
• Trouble swallowing
• A new mole or a change to a mole you already have

Cancer may cause various symptoms but often doesn't cause pain. Don't wait until you're having pain before seeing your health care provider. See your provider if you have symptoms that don't get better in a few weeks.

There is no single test that can diagnose cancer. The tests ordered are usually based on your symptoms. Your provider may:

• Ask about your medical history
• Ask about your family health history, including relatives who have had cancer
• Do a physical exam
• Do a screening test such as a mammogram, colonoscopy, or a Pap test
• Order blood tests or imaging tests

To find out if you have cancer, your provider may order a biopsy. A biopsy is the procedure of removing and examining tissue, cells, or fluids from your body.

Treatment depends on the type of cancer and how advanced it is. Most treatment plans may include surgery, radiation, and/or chemotherapy. Some may involve hormone therapy, immunotherapy or other types of biological therapy, or stem cell transplantation.

It's usually not possible to know exactly why cancer develops in some people but not others. There are some things that you can't control which may increase or decrease your risk of getting cancer, such as inheriting certain genes or your age. But some lifestyle habits may increase your risk of certain types of cancer. Avoid or reduce lifestyle habits such as:

• Smoking and tobacco use
• Having too much sun exposure
• Drinking too much alcohol
• Not getting enough physical activity
• Having obesity

NIH: National Cancer Institute

Throat cancer is a type of head and neck cancer. Throat cancer has different names, depending on which part of the throat is affected. The different parts of your throat are called the oropharynx, the hypopharynx, the nasopharynx, and the larynx, or voice box.

The main risk factors for throat cancer are tobacco use and heavy drinking. Certain types of throat cancer also have other risk factors. For example, having HPV is a risk factor for oropharyngeal cancer.

Symptoms of throat cancer may include:

• A sore throat that does not go away
• A lump in the neck
• Pain or ringing in the ears
• Trouble swallowing
• Ear pain

To diagnose throat cancers, doctors may do a physical exam and history, imaging tests, and a biopsy. You may also need other tests, depending on the type of cancer. Treatments include surgery, radiation therapy, and chemotherapy. Treatment for some types of throat cancer may also include targeted therapy. Targeted therapy uses drugs or other substances that attack specific cancer cells with less harm to normal cells.

NIH: National Cancer Institute

Your small intestine is part of your digestive system. It is a long tube that connects your stomach to your large intestine. Intestinal cancer is rare, but eating a high-fat diet or having Crohn's disease, celiac disease, or a history of colonic polyps can increase your risk.

Possible signs of small intestine cancer include:

• Abdominal pain
• Weight loss for no reason
• Blood in the stool
• A lump in the abdomen

Imaging tests that create pictures of the small intestine and the area around it can help diagnose intestinal cancer and show whether it has spread.

Surgery is the most common treatment. Additional options include chemotherapy, radiation therapy, or a combination.

NIH: National Cancer Institute

Your paranasal sinuses are small hollow spaces around the nose. They are lined with cells that make mucus, which keeps your nose from drying out. The nasal cavity is the passageway just behind your nose. Air passes through it on the way to your throat as you breathe.

Cancer of the nasal cavity and paranasal sinuses is rare. You are at greater risk if you are:

• Male and over 40 years old
• Exposed to certain workplace chemicals
• Infected with HPV
• A smoker

There may be no symptoms at first, and later symptoms can be like those of infections. Doctors diagnose nasal cancer with imaging tests, lighted tube-like instruments that look inside the nose, and biopsies. Treatment options include surgery, radiation, and chemotherapy.

NIH: National Cancer Institute

Cancer is a common disease. Many Americans will be diagnosed with cancer during their lifetimes. Even though cancer may be life-threatening, many people have successful treatment. Others live with cancer for a very long time.

For most people with cancer, learning to live with the disease is one of the biggest challenges they've ever faced. That's because having cancer touches just about every part of your life and the lives of those around you.

Cancer and its treatment may change:

• Your daily routines and ability to work
• Your important relationships
• The way you look, feel, and think about yourself

If you learn what to expect, you may feel more in control and prepared to cope with these changes. Your health care provider can help you find information and support services that are right for you.

Having cancer may cause a range of strong emotions, such as sadness, anger, fear, worry, or guilt. These feelings are normal, and they're likely to change over time. It's helpful to sort out your feelings in a way that's comfortable for you. You might try:

• Talking openly with someone you trust
• Writing about your feelings
• Using relaxation methods, such as meditation and other complementary and alternative medicine (CAM)
• Doing the things you enjoy, giving yourself a break from focusing on cancer

If your emotions seem to take over your life, tell your provider. You may need extra support if you have symptoms of depression, stress, anxiety, or panic disorder.

During cancer treatment, you usually have a team of providers. Along with doctors and nurses, you may be able to talk with social workers, pharmacists, dietitians, and other health professionals.

These professionals are prepared to help you deal with the issues that cancer brings up, including concerns about finances. But it's up to you to let your team know what's on your mind.

Good communication with your providers may help you feel more in control and satisfied with your care. Your communications may be better if you:

• Tell your providers how much you want to know about your cancer and its treatment. Do you want all the details or just the big picture?
• Write down your questions and concerns before your visits.
• Bring a family member or a friend to your visits. This person can help by listening, taking notes, and asking questions.

Cancer changes the daily routines and roles of the people who love and support you. They may need to start doing the things you've always done for them. And you may need their help doing things you've always done for yourself. These changes can be difficult for everyone.

It may help to have an honest talk about changing roles and needs. If that sounds too hard, ask a social worker or another member of your care team to help you talk with family and friends who are helping with your care. These caregivers may need some support, too.

Cancer and its treatment may cause some big changes in how you look, feel, and think about yourself. For example, you may have:

• Less energy
• Temporary or permanent changes in your body, such as scars, or hair loss from chemotherapy
• Problems being sexually close or doubts about dating

Coping with these changes can be hard. But most people find ways to feel more positive over time. If you feel well enough, you might try:

• Exercise. Walking, yoga, or other types of movement may help you feel stronger and more in control of your body. But check with your provider first.
• Staying involved in life and helping others. Think about volunteering, hobbies, or other activities that might make you feel good about yourself.
• Counseling for sexual problems. Talking with a professional, either with a partner or on your own, may help.

After treatment, you'll have regular cancer follow-up care. Your provider will explain the schedule of checkups and tests you'll need. This is a good time to discuss the challenges you may face ahead. Knowing what to expect may help you make plans as you find a "new normal" with cancer as part of your life.

NIH: National Cancer Institute