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Cancer isn't one disease but many. It starts in your cells, the building blocks of your body. Normally your body makes new cells as needed to replace old ones that die. Sometimes this goes wrong: new cells grow when they aren't needed, and old cells don't die when they should. The extra cells can form a mass called a tumor.
| Tumor type | What it means |
|---|---|
| Benign | Not cancer |
| Malignant | Cancer — its cells can invade nearby tissue and break away to spread to other parts of the body, called metastasis |
Types
There are more than 100 types of cancer, and it can start almost anywhere in the body.
- Most are named for where they start — lung cancer in the lung, breast cancer in the breast.
- Some are named for the type of cell: a sarcoma begins in bone and soft tissue; a carcinoma, the most common type, forms in epithelial cells, which cover the inside and outside surfaces of the body.
How cancer develops
Cancer is a genetic disease, caused by changes (variants or mutations) in your genes, the parts of DNA you inherit from your parents. Only some cancers come from inherited genes; others arise from genetic changes over a lifetime. Your body usually gets rid of damaged cells before they turn cancerous, but that ability declines with age. Other risk factors include:
- ultraviolet (UV) rays from the sun;
- smoking;
- diet;
- physical inactivity.
Symptoms
Symptoms depend on the type. Examples include:
- a lump in the breast;
- blood in urine or stool;
- bleeding or bruising for no known reason;
- a sore that doesn't heal;
- trouble swallowing;
- a new mole or a change in an existing one.
Cancer often doesn't cause pain — don't wait for pain. See a provider if symptoms don't improve within a few weeks.
Diagnosis
No single test diagnoses cancer. Depending on your symptoms, a provider may ask about your medical and family history, do a physical exam, use screening tests such as a mammogram, colonoscopy or Pap test, and order blood or imaging tests. A biopsy — removing and examining tissue, cells or fluid — can show whether you have cancer.
Treatment
Treatment depends on the type and how advanced it is. Most plans include surgery, radiation and/or chemotherapy; some use hormone therapy, immunotherapy or other biological therapy, or stem cell transplantation.
Prevention
It's usually impossible to know exactly why one person gets cancer and another doesn't, and some factors — such as inherited genes and age — are beyond your control. But you can lower your risk by avoiding or cutting back on:
- smoking and tobacco;
- too much sun;
- too much alcohol;
- too little physical activity;
- obesity.
Sources
Based on the MedlinePlus health topic "Cancer," National Library of Medicine, with a summary from NIH's National Cancer Institute; a work of the United States government in the public domain.
Лицензия: CC0 1.0 (общественное достояние) · По материалам medlineplus.gov
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