Comprehensive Overview of Breast Cancer
Breast cancer is a disease in which abnormal cells grow in the breast and form tumors. These cancer cells usually begin in the milk ducts or milk-producing glands called lobules.
Breast cancer is one of the most common cancers worldwide. It can affect both women and men, although it is much more common in women.
This guide explains what breast cancer is, breast cancer symptoms, how breast cancer develops, causes, stages, treatment, and prevention.
This information is educational only and not medical advice.
What Is Breast Cancer
Breast cancer begins when cells inside the breast develop DNA changes that allow them to grow uncontrollably and avoid normal cell death.
As these abnormal cells multiply, they can form a tumor. Over time the tumor may invade nearby tissue and spread to lymph nodes or distant organs.
Breast cancer most often starts in:
- Milk ducts (ductal cancer)
- Milk-producing glands called lobules (lobular cancer)
These processes explain why breast cancer symptoms often appear in the skin, nipple, breast shape, and lymph nodes.
How Breast Cancer Develops
Breast cancer develops gradually as cells accumulate genetic changes.
Normal breast cells:
- Grow in a controlled way
- Replace damaged cells
- Die when necessary
Breast cancer cells:
- Grow continuously
- Avoid cell death
- Form tumors
- Spread to nearby tissue
Over time tumors can grow large enough to affect breast shape and structure.
Cancer cells can also spread through:
- Lymphatic vessels
- Blood vessels
Common sites of spread include:
- Lymph nodes
- Bones
- Lungs
- Liver
- Brain
Breast Cancer Symptoms
Breast cancer symptoms vary from person to person. Early breast cancer may cause no symptoms at all, which is why screening is important.
Many breast changes are not cancer, but any new or unusual change should be medically evaluated.
Common breast cancer symptoms include:
- new lump or mass
- breast thickening
- swelling
- skin changes
- nipple changes
- breast shape changes
Core Breast Cancer Symptoms
These are often the first symptoms people notice.
New Lump or Mass
A new lump is the most common symptom.
Cancer lumps are often:
- firm
- irregular
- painless
However, lumps may also be:
- soft
- round
- tender
Lumps may occur in:
- the breast
- under the arm
- near the collarbone
Thickening or Swelling
Breast cancer may cause:
- thickened tissue
- swelling of part of the breast
- heaviness
This may occur even without a distinct lump.
Skin Changes
Tumors can affect the skin covering the breast.
Symptoms include:
- dimpling or puckering
- orange-peel texture (peau d’orange)
- redness
- discoloration
- warmth
- skin thickening
Skin redness may appear:
- pink or red on lighter skin
- darker or purple on darker skin
Changes in Breast Shape
Breast cancer may change the appearance of the breast.
Changes include:
- increased size
- decreased size
- asymmetry
- contour changes
These changes may develop gradually.
Nipple Symptoms
Breast cancer often affects the ducts, which connect to the nipple.
Symptoms include:
Nipple Retraction
The nipple may begin to pull inward.
This is called nipple inversion or retraction.
Nipple Discharge
Discharge not related to breastfeeding may be concerning.
Discharge may be:
- clear
- bloody
- one-sided
Bloody discharge requires evaluation.
Nipple Skin Changes
Symptoms include:
- flaking
- crusting
- scaling
These symptoms may resemble eczema.
Nipple Pain
Persistent nipple pain that is not related to hormonal cycles should be evaluated.
Deep Tissue Symptoms
These symptoms reflect deeper structural changes.
Symptoms include:
- firm thickened areas
- persistent breast pain
- lymph node swelling
Lymph nodes may enlarge:
- under the arm
- above the collarbone
Swollen lymph nodes may appear before a breast lump develops.
Inflammatory Breast Cancer Symptoms
Inflammatory breast cancer is an aggressive type that often does not form a lump.
Symptoms develop quickly over weeks.
Symptoms include:
- sudden swelling
- redness over a large area
- skin thickening
- orange-peel texture
- warmth
- tenderness
These symptoms occur when cancer blocks lymphatic vessels in the skin.
Inflammatory breast cancer requires urgent evaluation.
Symptoms of Metastatic Breast Cancer
Metastatic breast cancer occurs when cancer spreads beyond the breast.
Symptoms depend on the organ involved.
Bone Spread
Symptoms include:
- bone pain
- fractures
Lung Spread
Symptoms include:
- shortness of breath
- persistent cough
Liver Spread
Symptoms include:
- abdominal pain
- jaundice
- weight loss
Brain Spread
Symptoms include:
- headaches
- vision changes
- neurological symptoms
These symptoms usually occur in advanced disease.
Why Breast Cancer Symptoms Vary
Symptoms vary depending on several factors.
These include:
- tumor location
- tumor biology
- hormone receptor status
- HER2 status
- breast density
- age
- hormone levels
Benign conditions can mimic breast cancer.
Examples include:
- cysts
- fibrocystic breasts
- infections
Medical evaluation is needed to determine the cause.
Causes and Risk Factors
Breast cancer develops from genetic changes combined with environmental factors.
Risk factors include:
- increasing age
- family history
- inherited gene mutations
- hormone exposure
- obesity
- alcohol use
- inactivity
Some people develop breast cancer without known risk factors.
How Breast Cancer Is Diagnosed
Diagnosis may include:
- physical exam
- mammogram
- ultrasound
- MRI
- biopsy
A biopsy confirms breast cancer.
Breast Cancer Stages
Stage 0
Cancer limited to ducts or lobules.
Stage 1
Small tumor confined to breast.
Stage 2
Larger tumor or limited lymph node spread.
Stage 3
Extensive lymph node involvement.
Stage 4
Cancer has spread to distant organs.
Breast Cancer Treatment
Treatment depends on stage and tumor biology.
Surgery
Surgery removes tumors.
Types include:
- lumpectomy
- mastectomy
Radiation Therapy
Radiation destroys cancer cells after surgery.
Chemotherapy
Chemotherapy kills rapidly dividing cells.
Hormone Therapy
Hormone therapy blocks estrogen or progesterone.
Used in hormone-sensitive cancers.
Targeted Therapy
Targeted therapy attacks specific cancer proteins.
Immunotherapy
Immunotherapy helps immune cells attack cancer.
Used in certain breast cancers.
Breast Cancer Prevention
Risk can be reduced by:
- regular screening
- maintaining healthy weight
- regular exercise
- limiting alcohol
- avoiding smoking
Screening improves early detection.
When to Seek Medical Evaluation
Medical evaluation is important if you notice:
- a new lump
- persistent skin changes
- nipple discharge
- breast shape changes
- persistent pain
- swollen lymph nodes
Even with a normal mammogram, new symptoms should be evaluated.
Medical References
National Cancer Institute
https://www.cancer.gov/types/breast
American Cancer Society
https://www.cancer.org/cancer/breast-cancer.html
Mayo Clinic
https://www.mayoclinic.org/diseases-conditions/breast-cancer
CDC
https://www.cdc.gov/cancer/breast
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