Cancer - Symptoms and causes (2023)

Overview

Cancer refers to any one of a large number of diseases characterized by the development of abnormal cells that divide uncontrollably and have the ability to infiltrate and destroy normal body tissue. Cancer often has the ability to spread throughout your body.

Cancer is the second-leading cause of death in the world. But survival rates are improving for many types of cancer, thanks to improvements in cancer screening, treatment and prevention.

Symptoms

Signs and symptoms caused by cancer will vary depending on what part of the body is affected.

Some general signs and symptoms associated with, but not specific to, cancer, include:

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  • Fatigue
  • Lump or area of thickening that can be felt under the skin
  • Weight changes, including unintended loss or gain
  • Skin changes, such as yellowing, darkening or redness of the skin, sores that won't heal, or changes to existing moles
  • Changes in bowel or bladder habits
  • Persistent cough or trouble breathing
  • Difficulty swallowing
  • Hoarseness
  • Persistent indigestion or discomfort after eating
  • Persistent, unexplained muscle or joint pain
  • Persistent, unexplained fevers or night sweats
  • Unexplained bleeding or bruising

When to see a doctor

Make an appointment with your doctor if you have any persistent signs or symptoms that concern you.

If you don't have any signs or symptoms, but are worried about your risk of cancer, discuss your concerns with your doctor. Ask about which cancer screening tests and procedures are appropriate for you.

Request an Appointment at Mayo Clinic

Causes

Cancer is caused by changes (mutations) to the DNA within cells. The DNA inside a cell is packaged into a large number of individual genes, each of which contains a set of instructions telling the cell what functions to perform, as well as how to grow and divide. Errors in the instructions can cause the cell to stop its normal function and may allow a cell to become cancerous.

What do gene mutations do?

A gene mutation can instruct a healthy cell to:

  • Allow rapid growth. A gene mutation can tell a cell to grow and divide more rapidly. This creates many new cells that all have that same mutation.
  • Fail to stop uncontrolled cell growth. Normal cells know when to stop growing so that you have just the right number of each type of cell. Cancer cells lose the controls (tumor suppressor genes) that tell them when to stop growing. A mutation in a tumor suppressor gene allows cancer cells to continue growing and accumulating.
  • Make mistakes when repairing DNA errors. DNA repair genes look for errors in a cell's DNA and make corrections. A mutation in a DNA repair gene may mean that other errors aren't corrected, leading cells to become cancerous.

These mutations are the most common ones found in cancer. But many other gene mutations can contribute to causing cancer.

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What causes gene mutations?

Gene mutations can occur for several reasons, for instance:

  • Gene mutations you're born with. You may be born with a genetic mutation that you inherited from your parents. This type of mutation accounts for a small percentage of cancers.
  • Gene mutations that occur after birth. Most gene mutations occur after you're born and aren't inherited. A number of forces can cause gene mutations, such as smoking, radiation, viruses, cancer-causing chemicals (carcinogens), obesity, hormones, chronic inflammation and a lack of exercise.

Gene mutations occur frequently during normal cell growth. However, cells contain a mechanism that recognizes when a mistake occurs and repairs the mistake. Occasionally, a mistake is missed. This could cause a cell to become cancerous.

How do gene mutations interact with each other?

The gene mutations you're born with and those that you acquire throughout your life work together to cause cancer.

For instance, if you've inherited a genetic mutation that predisposes you to cancer, that doesn't mean you're certain to get cancer. Instead, you may need one or more other gene mutations to cause cancer. Your inherited gene mutation could make you more likely than other people to develop cancer when exposed to a certain cancer-causing substance.

It's not clear just how many mutations must accumulate for cancer to form. It's likely that this varies among cancer types.

More Information

  • Cancer care at Mayo Clinic
  • Myths about cancer causes
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Risk factors

While doctors have an idea of what may increase your risk of cancer, the majority of cancers occur in people who don't have any known risk factors. Factors known to increase your risk of cancer include:

Your age

Cancer can take decades to develop. That's why most people diagnosed with cancer are 65 or older. While it's more common in older adults, cancer isn't exclusively an adult disease — cancer can be diagnosed at any age.

Your habits

Certain lifestyle choices are known to increase your risk of cancer. Smoking, drinking more than one drink a day for women and up to two drinks a day for men, excessive exposure to the sun or frequent blistering sunburns, being obese, and having unsafe sex can contribute to cancer.

You can change these habits to lower your risk of cancer — though some habits are easier to change than others.

Your family history

Only a small portion of cancers are due to an inherited condition. If cancer is common in your family, it's possible that mutations are being passed from one generation to the next. You might be a candidate for genetic testing to see whether you have inherited mutations that might increase your risk of certain cancers. Keep in mind that having an inherited genetic mutation doesn't necessarily mean you'll get cancer.

Your health conditions

Some chronic health conditions, such as ulcerative colitis, can markedly increase your risk of developing certain cancers. Talk to your doctor about your risk.

Your environment

The environment around you may contain harmful chemicals that can increase your risk of cancer. Even if you don't smoke, you might inhale secondhand smoke if you go where people are smoking or if you live with someone who smokes. Chemicals in your home or workplace, such as asbestos and benzene, also are associated with an increased risk of cancer.

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Complications

Cancer and its treatment can cause several complications, including:

  • Pain. Pain can be caused by cancer or by cancer treatment, though not all cancer is painful. Medications and other approaches can effectively treat cancer-related pain.
  • Fatigue. Fatigue in people with cancer has many causes, but it can often be managed. Fatigue associated with chemotherapy or radiation therapy treatments is common, but it's usually temporary.
  • Difficulty breathing. Cancer or cancer treatment may cause a feeling of being short of breath. Treatments may bring relief.
  • Nausea. Certain cancers and cancer treatments can cause nausea. Your doctor can sometimes predict if your treatment is likely to cause nausea. Medications and other treatments may help you prevent or decrease nausea.
  • Diarrhea or constipation. Cancer and cancer treatment can affect your bowels and cause diarrhea or constipation.
  • Weight loss. Cancer and cancer treatment may cause weight loss. Cancer steals food from normal cells and deprives them of nutrients. This is often not affected by how many calories or what kind of food is eaten; it's difficult to treat. In most cases, using artificial nutrition through tubes into the stomach or vein does not help change the weight loss.
  • Chemical changes in your body. Cancer can upset the normal chemical balance in your body and increase your risk of serious complications. Signs and symptoms of chemical imbalances might include excessive thirst, frequent urination, constipation and confusion.
  • Brain and nervous system problems. Cancer can press on nearby nerves and cause pain and loss of function of one part of your body. Cancer that involves the brain can cause headaches and stroke-like signs and symptoms, such as weakness on one side of your body.
  • Unusual immune system reactions to cancer. In some cases the body's immune system may react to the presence of cancer by attacking healthy cells. Called paraneoplastic syndromes, these very rare reactions can lead to a variety of signs and symptoms, such as difficulty walking and seizures.
  • Cancer that spreads. As cancer advances, it may spread (metastasize) to other parts of the body. Where cancer spreads depends on the type of cancer.
  • Cancer that returns. Cancer survivors have a risk of cancer recurrence. Some cancers are more likely to recur than others. Ask your doctor about what you can do to reduce your risk of cancer recurrence. Your doctor may devise a follow-up care plan for you after treatment. This plan may include periodic scans and exams in the months and years after your treatment, to look for cancer recurrence.

Prevention

Doctors have identified several ways to reduce your risk of cancer, such as:

  • Stop smoking. If you smoke, quit. If you don't smoke, don't start. Smoking is linked to several types of cancer — not just lung cancer. Stopping now will reduce your risk of cancer in the future.
  • Avoid excessive sun exposure. Harmful ultraviolet (UV) rays from the sun can increase your risk of skin cancer. Limit your sun exposure by staying in the shade, wearing protective clothing or applying sunscreen.
  • Eat a healthy diet. Choose a diet rich in fruits and vegetables. Select whole grains and lean proteins. Limit your intake of processed meats.
  • Exercise most days of the week. Regular exercise is linked to a lower risk of cancer. Aim for at least 30 minutes of exercise most days of the week. If you haven't been exercising regularly, start out slowly and work your way up to 30 minutes or longer.
  • Maintain a healthy weight. Being overweight or obese may increase your risk of cancer. Work to achieve and maintain a healthy weight through a combination of a healthy diet and regular exercise.
  • Drink alcohol in moderation, if you choose to drink. If you choose to drink alcohol, do so in moderation. For healthy adults, that means up to one drink a day for women and up to two drinks a day for men.
  • Schedule cancer screening exams. Talk to your doctor about what types of cancer screening exams are best for you based on your risk factors.
  • Ask your doctor about immunizations. Certain viruses increase your risk of cancer. Immunizations may help prevent those viruses, including hepatitis B, which increases the risk of liver cancer, and human papillomavirus (HPV), which increases the risk of cervical cancer and other cancers. Ask your doctor whether immunization against these viruses is appropriate for you.

By Mayo Clinic Staff

Dec. 07, 2022

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FAQs

What are the 7 cancer warning signs? ›

7 Signs and Symptoms of Cancer
  • Change in bowel or bladder habits.
  • A sore that does not heal.
  • Unusual bleeding or discharge.
  • Thickening or lump in breast or elsewhere.
  • Indigestion or difficulty in swallowing.
  • Obvious change in wart or mole.
  • Nagging cough or hoarseness.

What are the top 10 causes of cancer? ›

Contents
  • 1 Genetics. 1.1 Cancer syndromes.
  • 2 Physical and chemical agents. 2.1 Smoking. 2.2 Materials.
  • 3 Lifestyle. 3.1 Alcohol. 3.2 Diet. ...
  • 4 Hormones.
  • 5 Infection and inflammation. 5.1 Viruses. 5.2 Bacteria and parasites. ...
  • 6 Radiation. 6.1 Non-ionizing radiation. ...
  • 7 Rare causes. 7.1 Organ transplantation. ...
  • 8 References.

What are the silent signs of cancer? ›

Signs and symptoms:
  • A change in bowel habits, including diarrhoea, constipation or consistency of your stool.
  • A feeling that your bowel doesn't empty completely.
  • Persistent abdominal discomfort such as cramps, gas or pain.
  • Rectal bleeding or blood in your stool.
  • Unexplained weight loss.
  • Weakness or fatigue.
Dec 17, 2021

What are the red flags for cancer? ›

Warning Signs of Cancer
  • Unexplained weight loss.
  • Fatigue.
  • Night sweats.
  • Loss of appetite.
  • New, persistent pain.
  • Problems with vision or hearing.
  • Recurrent nausea or vomiting.
  • Blood in urine.

What is the biggest symptom of cancer? ›

Fatigue or extreme tiredness that doesn't get better with rest. Skin changes such as a lump that bleeds or turns scaly, a new mole or a change in a mole, a sore that does not heal, or a yellowish color to the skin or eyes (jaundice).

Where does cancer usually start? ›

Cancer can start almost anywhere in the human body, which is made up of trillions of cells. Normally, human cells grow and multiply (through a process called cell division) to form new cells as the body needs them. When cells grow old or become damaged, they die, and new cells take their place.

How long can you have cancer before you know it? ›

If you're wondering how long you can have cancer without knowing it, there's no straight answer. Some cancers can be present for months or years before they're detected. Some commonly undetected cancers are slow-growing conditions, which gives doctors a better chance at successful treatment.

How to avoid getting cancer? ›

Consider these lifestyle tips to help prevent cancer.
  1. Don't use tobacco. ...
  2. Eat a healthy diet. ...
  3. Maintain a healthy weight and be physically active. ...
  4. Protect yourself from the sun. ...
  5. Get vaccinated. ...
  6. Avoid risky behaviors. ...
  7. Get regular medical care.

Can stress cause cancer? ›

While plenty of research has shown that stress can cause cancer to grow and spread in mice, studies haven't shown a clear link between stress and cancer outcomes in people. But it's difficult to study stress in people for several reasons, including challenges with defining and measuring stress.

Will cancer show up in blood work? ›

Aside from leukemia, most cancers cannot be detected in routine blood work, such as a CBC test. However, specific blood tests are designed to identify tumor markers, which are chemicals and proteins that may be found in the blood in higher quantities than normal when cancer is present.

How can I check if I have cancer? ›

Cancer diagnosis
  1. Physical exam. Your doctor may feel areas of your body for lumps that may indicate cancer. ...
  2. Laboratory tests. Laboratory tests, such as urine and blood tests, may help your doctor identify abnormalities that can be caused by cancer. ...
  3. Imaging tests. ...
  4. Biopsy.

Can blood tests detect cancer? ›

Most blood tests aren't used on their own to diagnose cancer. But they can provide clues that may lead your health care team to make the diagnosis. For most types of cancer, a procedure to remove a sample of cells for testing is often needed to be sure.

What does early stages of cancer feel like? ›

Sometimes symptoms affect specific areas of the body, such as our tummy or skin. But signs can also be more general, and include weight loss, tiredness (fatigue) or unexplained pain. Some possible signs of cancer, like a lump, are better known than others.

What does cancer fatigue feel like? ›

People with cancer might describe it as feeling very weak, listless, drained, or “washed out” that may decrease for a while but then comes back. Some may feel too tired to eat, walk to the bathroom, or even use the TV remote. It can be hard to think or move.

Can you feel fine with cancer? ›

Sometimes, a cancer diagnosis comes out of the blue, with no symptoms at all. But more often, there are various symptoms that may be warning signs of the disease.

How does your body act when you have cancer? ›

Cancer can upset the normal chemical balance in your body and increase your risk of serious complications. Signs and symptoms of chemical imbalances might include excessive thirst, frequent urination, constipation and confusion. Brain and nervous system problems.

Do you feel anything if you have cancer? ›

Often, cancer does not cause pain, so do not wait to feel pain before seeing a doctor. To learn more about symptoms for a specific cancer, see the list of PDQ® cancer treatment summaries for adult and childhood cancers. Each summary includes detailed information about symptoms caused by a specific cancer.

What does cancer pain feel like? ›

Cancer pain can be described as dull aching, pressure, burning, or tingling. The type of pain often gives clues about the sources of the pain. For example, pain caused by damage to nerves is usually described as burning or tingling, whereas pain affecting internal organs is often described as a sensation of pressure.

What is the most common age to get cancer? ›

According to the most recent statistical data from NCI's Surveillance, Epidemiology, and End Results (SEER) Program, the median age of a cancer diagnosis is 66 years. This means that half of cancer cases occur in people below this age and half in people above this age.

What age group is most likely to get cancer? ›

You're more likely to get cancer as you get older. In fact, age is the biggest risk factor for the disease. More than nine out of 10 cancers are diagnosed in people 45 and older. Those older than 74 make up almost 28% of all new cancer cases.

What is the first stage of cancer? ›

stage 1 – the cancer is small and hasn't spread anywhere else. stage 2 – the cancer has grown, but hasn't spread. stage 3 – the cancer is larger and may have spread to the surrounding tissues and/or the lymph nodes (or "glands", part of the immune system)

Which cancer is the hardest to detect early? ›

Pancreatic cancer is hard to find early. The pancreas is deep inside the body, so early tumors can't be seen or felt by health care providers during routine physical exams. People usually have no symptoms until the cancer has become very large or has already spread to other organs.

Do you feel different when you have cancer? ›

There are over 200 different types of cancer that can cause many different signs and symptoms. Sometimes symptoms affect specific areas of the body, such as our tummy or skin. But signs can also be more general, and include weight loss, tiredness (fatigue) or unexplained pain.

What does fatigue from cancer feel like? ›

People with cancer might describe it as feeling very weak, listless, drained, or “washed out” that may decrease for a while but then comes back. Some may feel too tired to eat, walk to the bathroom, or even use the TV remote. It can be hard to think or move.

How can I check my body for cancer? ›

Cancer diagnosis
  1. Physical exam. Your doctor may feel areas of your body for lumps that may indicate cancer. ...
  2. Laboratory tests. Laboratory tests, such as urine and blood tests, may help your doctor identify abnormalities that can be caused by cancer. ...
  3. Imaging tests. ...
  4. Biopsy.

Does cancer show up in routine blood work? ›

Most blood tests aren't used on their own to diagnose cancer. But they can provide clues that may lead your health care team to make the diagnosis. For most types of cancer, a procedure to remove a sample of cells for testing is often needed to be sure.

How long until you know you have cancer? ›

It can take anywhere from a few days to a few weeks to find out if it's cancer and, if so, what kind of cancer. This is a difficult time for the patient as well as for loved ones who are aware of the possibility of cancer. Some notice that they think of worst-case scenarios and wonder if they'll lose their loved one.

What type of cancer makes you very tired? ›

Fatigue may develop as a symptom of blood cancers, such as leukemia, lymphoma and multiple myeloma, because these cancers start in the bone marrow, which produces red blood cells that carry oxygen throughout the body.

What are the signs of cancer in a woman? ›

17 Cancer Symptoms You Shouldn't Ignore
  • Abnormal periods or pelvic pain. Most women have the occasional irregular period or cramps. ...
  • Changes in bathroom habits. ...
  • Bloating. ...
  • Breast changes. ...
  • Chronic coughing. ...
  • Chronic headache. ...
  • Difficulty swallowing. ...
  • Excessive bruising.
Dec 2, 2021

Does cancer make you feel sick? ›

Some people in the advanced stages of cancer may feel or be sick a lot. This type of sickness is very different to that of people having chemotherapy or radiotherapy. It can severely affect your day to day life and make you very tired and depressed.

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2. 6 Warning Signs of Brain Tumors
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3. 10 Warning Signs of Prostate Cancer
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4. Endometrial cancer - causes, symptoms, diagnosis, treatment, pathology
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5. Signs and Symptoms of Lung Cancer | Dana-Farber Cancer Institute
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6. Lung Cancer: Symptoms, Causes and Treatment
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