Breast tissue responds to estrogen, progesterone, and prolactin across the menstrual cycle, pregnancy, lactation, and menopause. Most breast lumps are benign, but every new mass needs evaluation because breast cancer is the most common cancer in women worldwide.

Benign breast conditions

Mastitis spectrum. Current lactation guidance views mastitis as a continuum from ductal narrowing and tissue edema (inflammatory) to bacterial mastitis and abscess. Aggressive deep massage and overemptying the affected breast (extra pumping) can increase inflammation and edema.

Breast cancer

• Most are adenocarcinomas arising from ducts (invasive ductal carcinoma) or lobules; ductal carcinoma in situ (DCIS) is non-invasive
• Spreads to axillary lymph nodes, then bone, lung, liver, and brain
• Receptor status guides treatment and prognosis:
  • Hormone receptor positive (estrogen receptor/progesterone receptor): responds to endocrine therapy
  • HER2-positive: more aggressive, but responds to HER2-targeted drugs
  • Triple-negative: no ER, PR, or HER2 — aggressive; chemotherapy and immunotherapy
• Risk factors: female sex, increasing age, BRCA1/BRCA2 and other inherited mutations, family history, prior chest radiation, dense breasts, early menarche, late menopause, nulliparity or first birth after 30, combined menopausal hormone therapy, alcohol, obesity after menopause, physical inactivity. Breastfeeding is protective

Breast cancer

• Usually a painless, hard, irregular, fixed (non-mobile) mass, most often in the upper outer quadrant
• Skin dimpling or retraction, peau d'orange (orange-peel skin from lymphatic blockage), nipple retraction, bloody nipple discharge, nipple scaling (Paget disease of the nipple)
• Enlarged, hard axillary or supraclavicular lymph nodes
• Inflammatory breast cancer: rapidly red, swollen, warm breast without a distinct lump — can be mistaken for mastitis
• Advanced disease: bone pain, dyspnea, jaundice, headache or neurologic changes

Benign features — tender, mobile, cyclic changes (fibrocystic); smooth, rubbery, mobile (fibroadenoma).

Mastitis — breast redness, swelling, pain, fever 38.5 °C (101.3 °F) or higher, chills, malaise.

BI-RADS assessment categories

Surgery

• Breast-conserving surgery (lumpectomy) plus radiation gives survival equivalent to mastectomy for suitable clients
• Breast-conserving surgery is usually not appropriate with: tumors large relative to breast size, multicentric disease (tumors in different quadrants), diffuse suspicious calcifications, inability to receive radiation (e.g., prior chest radiation, some connective tissue diseases, pregnancy when radiation would be needed during it), persistently positive margins, or client preference
• Mastectomy with or without reconstruction (implants or tissue flaps)
• Sentinel lymph node biopsy has largely replaced full axillary dissection in clinically node-negative disease, reducing lymphedema risk

Radiation therapy — after breast conservation and for some post-mastectomy clients. Skin reactions (redness, dryness, peeling), fatigue.

Systemic therapy

Benign disease — fibrocystic changes: supportive bra, NSAIDs, cyst aspiration; fibroadenoma: observation or excision; papilloma: excision of the duct.

Mastitis (lactational)

• Continue breastfeeding on demand from both breasts; avoid overemptying or extra pumping of the affected breast
• Ice or cold packs between feeds and NSAIDs (ibuprofen) for pain and inflammation; gentle lymphatic drainage (light stroking toward the axilla) rather than deep massage
• Antibiotics (e.g., dicloxacillin or cephalexin; alternatives for MRSA) when bacterial mastitis is suspected or symptoms do not improve within about 12–24 hours of conservative care; most options are compatible with breastfeeding
• Abscess: ultrasound-guided aspiration or incision and drainage

Listed in priority order.

1. Post-mastectomy/lumpectomy safety
   • Airway and vital signs after anesthesia; monitor for hematoma (swelling, tightness, bleeding) and flap color and warmth after reconstruction
   • Closed suction drains (e.g., Jackson-Pratt): keep compressed, empty and record output, monitor color; report sudden increase in bright-red drainage
2. Infection and neutropenia precautions during chemotherapy: hand hygiene, report temperature 38 °C (100.4 °F) or higher immediately (febrile neutropenia is an emergency)
3. Lymphedema risk reduction on the affected arm (especially after axillary dissection or radiation)
   • Elevate the arm on pillows; begin prescribed exercises (hand squeezing, elbow flexion first, then shoulder exercises such as wall climbing as ordered)
   • Where possible, avoid blood pressure measurement, injections, and venipuncture on the affected side
4. Pain management and positioning
5. Radiation skin care: wash gently with lukewarm water and mild soap, pat dry; use only skin products approved by the radiation team; no heat, sun, tight clothing, or rubbing; do not remove skin markings
6. Chemotherapy symptom care: give antiemetics before treatment; soft, bland, non-irritating foods and gentle oral care for mucositis; for peripheral neuropathy, check water temperature with a thermometer or unaffected body part — never soak numb hands or feet in hot water
7. Psychosocial care: body image, sexuality, fear of recurrence; offer wigs or scarves for alopecia, prosthesis and reconstruction information, and peer support

Early detection

• Screening mammography according to national guidance (see Country Notes)
• Breast self-awareness: know how your breasts normally look and feel and report changes promptly. Routine monthly breast self-examination is no longer recommended as a stand-alone screening method by major guidelines; if a client chooses to do it, the best time is a few days after the menstrual period ends (about 1 week after it starts), when breasts are least tender, or the same date each month after menopause. Use the finger pads, both standing and lying, and include the nipple and axilla
• Inherited-risk clients: genetic counseling, earlier or MRI screening

After surgery

• Arm and shoulder exercises daily to regain motion; avoid heavy lifting early as instructed
• Lymphedema: lifelong awareness; protect the arm from cuts, burns, and insect bites; wear gloves for gardening; avoid tight sleeves or jewelry; maintain healthy weight; report arm heaviness, swelling, redness, or warmth promptly — do not apply heat; seek care early (compression therapy, manual lymphatic drainage). Supervised progressive exercise is safe and does not cause lymphedema
• Drain care at home, signs of infection

Medications

• Tamoxifen: report calf pain, chest pain, sudden dyspnea, abnormal vaginal bleeding, vision changes
• Aromatase inhibitors: weight-bearing exercise, calcium and vitamin D, bone density checks
• Trastuzumab: report shortness of breath, swelling, rapid weight gain

Mastitis — keep feeding; ice and ibuprofen; rest and fluids; seek care for high fever, spreading redness, or no improvement in 24 hours.

• Cancer mass: hard, irregular, fixed, painless, upper outer quadrant; skin dimpling, peau d'orange, nipple retraction
• Fibrocystic changes: tender, cyclic, ill-defined, mobile; fibroadenoma: rubbery, well-defined, very mobile
• BI-RADS 4 = suspicious → biopsy; BI-RADS 3 = short-interval follow-up
• Core needle biopsy confirms cancer and receptor status
• Breast conservation needs radiation; not suitable for multicentric disease, large tumor-to-breast ratio, or inability to receive radiation
• Tamoxifen: VTE and endometrial cancer — report abnormal vaginal bleeding
• Aromatase inhibitors: bone loss; trastuzumab: cardiotoxicity, check LVEF
• HER2-positive = aggressive but treatable with targeted therapy
• Lymphedema risk: protect the arm, avoid heat, report swelling early
• Radiation skin: only approved products, lukewarm water, no rubbing, no sun
• Mastitis: continue breastfeeding, ice, NSAIDs; avoid overemptying and deep massage; antibiotics if not improving
• Neuropathy: never soak numb feet or hands in hot water