HomeHealth TopicsCancersCancer
Back to Cancers
Cancer
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Cancers

Cancer

Cancer is a complex group of diseases characterized by the uncontrolled growth and spread of abnormal cells within the body.

What is cancer?

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.

What are the types of cancer?

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.

How does cancer develop?

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

What are the symptoms of cancer?

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.

How is cancer diagnosed?

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.

What are the treatments for cancer?

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.

Can cancer be prevented?

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

Frequently Asked Questions

While symptoms vary widely by cancer type, some general warning signs include unexplained weight loss, persistent fatigue, a new lump or thickening under the skin, changes in a mole or skin lesion, persistent cough or hoarseness, difficulty swallowing, changes in bowel or bladder habits, and unusual bleeding or discharge. It's important to see a doctor if you experience any new or persistent symptoms.
Many cancers are linked to lifestyle factors. Key preventive measures include maintaining a healthy weight, eating a balanced diet rich in fruits and vegetables, limiting processed foods and red meat, getting regular physical activity, avoiding tobacco products, limiting alcohol consumption, protecting your skin from excessive sun exposure, and getting recommended vaccinations like HPV and Hepatitis B. Regular screenings are also crucial for early detection.
If cancer is suspected, diagnosis usually involves a combination of methods. This can include physical exams, blood tests (looking for tumor markers or other abnormalities), imaging tests like X-rays, CT scans, MRI, or PET scans to visualize tumors, and most definitively, a biopsy. A biopsy involves taking a small tissue sample from the suspicious area and examining it under a microscope to confirm the presence of cancer cells.
No, not necessarily. While cancer is indeed a genetic disease, meaning it's caused by changes (mutations) in your genes, most cancers are not inherited. The majority of gene mutations that lead to cancer happen after birth, often due to environmental factors, lifestyle choices, or simply random errors during cell division. Only about 5-10% of cancers are strongly linked to inherited gene mutations passed down through families.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

kontakt@hittavard.se

Ⓒ 2024. Alla rättigheter förbehålls av juxt ab

Sök
Om ossVillkor och policyVanliga frågorKontakta oss