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GTR Home > Conditions/Phenotypes > Malignant tumor of breast

Summary

Breast cancer is a disease in which certain cells in the breast become abnormal and multiply uncontrollably to form a tumor. Although breast cancer is much more common in women, this form of cancer can also develop in men. In both women and men, the most common form of breast cancer begins in cells lining the milk ducts (ductal cancer). In women, cancer can also develop in the glands that produce milk (lobular cancer). Most men have little or no lobular tissue, so lobular cancer in men is very rare. \n\nIn its early stages, breast cancer usually does not cause pain and may exhibit no noticeable symptoms. As the cancer progresses, signs and symptoms can include a lump or thickening in or near the breast; a change in the size or shape of the breast; nipple discharge, tenderness, or retraction (turning inward); and skin irritation, dimpling, redness, or scaliness. However, these changes can occur as part of many different conditions. Having one or more of these symptoms does not mean that a person definitely has breast cancer.\n\nIn some cases, cancerous cells can invade surrounding breast tissue. In these cases, the condition is known as invasive breast cancer. Sometimes, tumors spread to other parts of the body. If breast cancer spreads, cancerous cells most often appear in the bones, liver, lungs, or brain. Tumors that begin at one site and then spread to other areas of the body are called metastatic cancers.\n\nA small percentage of all breast cancers cluster in families. These cancers are described as hereditary and are associated with inherited gene mutations. Hereditary breast cancers tend to develop earlier in life than noninherited (sporadic) cases, and new (primary) tumors are more likely to develop in both breasts. [from MedlinePlus Genetics]

Genes See tests for all associated and related genes

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Suggested reading

Clinical resources

Practice guidelines

  • NICE, 2024
    UK NICE Guideline NG101, Early and locally advanced breast cancer: diagnosis and management, 2024
  • NICE, 2023
    UK NICE Guideline NG12, Suspected cancer: recognition and referral, 2023
  • NCCN, 2023
    NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) Breast Cancer, 2023
  • NCCN, 2023
    Breast Cancer, NCCN Guidelines Version 4.2022
  • NICE, 2018
    Tumour profiling tests to guide adjuvant chemotherapy decisions in early breast cancer (DG34)

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