Breast Cancer
Invasive ductal carcinoma High-yield Verified · Sep 2026Breast cancer is a malignancy of breast tissue — most often invasive ductal carcinoma, then lobular — classified by hormone-receptor and HER2 status into subtypes that determine prognosis and treatment.
Estrogen exposure and BRCA, the four molecular subtypes that decide treatment, the CDC warning signs, biennial mammography from 40 to 74, core biopsy, lumpectomy versus mastectomy and the sentinel node, post-mastectomy drain and bleeding care, lifelong lymphedema risk reduction, and what to watch for on tamoxifen, anastrozole and trastuzumab.
What’s going wrong in the body
The normal physiology, where it fails, and why the body’s compensation backfires.
01 Hormones, genes and the four subtypes
"Breast cancer is the most common noncutaneous cancer in U.S. women, with an estimated 59,080 cases of female breast ductal carcinoma in situ (DCIS) and 316,950 cases of invasive disease in 2025." "Men account for 1% of breast cancer cases and breast cancer deaths." "Most breast cancer is sporadic (90%-95%), with only 5% to 10% of patients having an identifiable genetic mutation" — chiefly BRCA1 and BRCA2, which carry an estimated lifetime breast cancer risk of 40% to 85%.
Longer estrogen exposure raises risk. "Reproductive milestones that increase a woman’s lifetime estrogen exposure are thought to increase breast cancer risk. These include the onset of menarche before age 12, first live childbirth after age 30 years, nulliparity, and menopause after the age of 55." The CDC: "Starting menstrual periods early and starting menopause at an older age expose women to hormones longer, raising their risk of getting breast cancer."
The receptors decide the disease. "All specimens should be tested for hormone receptors (ie, estrogen and progesterone) and HER-2 receptors." Luminal A is hormone receptor–positive and HER2-negative; luminal B is hormone receptor–positive and HER2-positive; HER2-enriched is HER2-positive and receptor-negative; basal-like (triple-negative) lacks all three. "Hormone receptor-positive tumors (ie, luminal A and B) tend to be less aggressive, with improved survival rates"; "HER-2 enriched tumors are more aggressive, with a poor prognosis without targeted therapy"; basal-like tumors "tend to have a worse prognosis with poor survival rates."
02 How it is found — symptoms, screening and biopsy
Often no symptoms. "Most breast cancer patients are asymptomatic, and lesions are discovered during routine breast examination or screening mammography." The CDC’s warning signs: "New lump in the breast or underarm (armpit). Thickening or swelling of part of the breast. Irritation or dimpling of breast skin. Redness or flaky skin in the nipple area or the breast. Pulling in of the nipple or pain in the nipple area. Nipple discharge other than breast milk, including blood. Any change in the size or the shape of the breast. Pain in any area of the breast." — and "If you have any signs or symptoms, be sure to see your doctor right away." Most lumps are benign, and StatPearls notes "Breast pain is an unusual symptom that happens 5% of the time."
Ductal vs lobular. Invasive ductal carcinoma, 50% to 75% of cases, is "often felt as a breast mass secondary to a significant fibrotic reaction." Invasive lobular cancer "tends to permeate the breast in a single-file nature," so it can remain "clinically occult, escaping detection on mammography or physical examination until the disease becomes extensive." Inflammatory breast cancer can mimic an abscess — "Inflammation or cellulitis that does not respond to antibiotics should be evaluated further."
Screening (USPSTF 2024). "The USPSTF recommends biennial screening mammography for women aged 40 to 74 years" (Grade B) — a change from the earlier individual decision in the 40s. Evidence is insufficient for women 75 and older and for supplemental ultrasound or MRI in dense breasts, but "all women, including those with dense breasts, should be screened starting at age 40." Diagnosis: "Once a suspicious lesion is identified, tissue biopsy with stereotactic core needle biopsy is performed with imaging guidance," and "Core needle biopsy is superior to fine needle aspiration."
03 Treatment — local control plus therapy matched to the subtype
Surgery. "Options to excise the primary tumor include breast conservation surgery (eg, partial mastectomy or lumpectomy) or a total mastectomy." Randomized trials show "no overall survival disadvantage with breast-conserving surgery plus radiotherapy compared with mastectomy," and patients having breast conservation "must receive radiation to the breast." The axilla: "Sentinel lymph node biopsy is a vital staging procedure in patients with a clinically negative axilla." Those with 1 to 3 positive sentinel nodes without gross extranodal extension "can safely avoid axillary lymph node dissection"; "Patients with clinically positive axillary nodes typically require an axillary lymph node dissection."
Systemic therapy follows the receptors. "Anti-estrogen or aromatase inhibitor therapy is indicated in all hormone receptor-positive patients"; "All HER2-positive patients with tumors >1 cm should receive anti-HER2-directed therapy. All triple-negative patients with tumors > 1 cm should receive systemic chemotherapy." In hormone receptor–positive disease the chemotherapy decision uses genomic risk testing. Neoadjuvant (up-front) therapy is increasingly used in triple-negative and HER2-positive tumors, increasing breast conservation (65% vs 49%) with no difference in recurrence or mortality.
Lymphedema — the lifelong arm risk. "Lymphedema is a chronic, progressive condition caused by impaired lymphatic drainage, leading to the abnormal accumulation of protein-rich lymphatic fluid in the interstitial tissues." "Lymph node dissection and adjuvant radiation act independently and synergistically to impair lymphatic drainage," and risk rises with "the extent of surgery, radiation dose, high body mass index (BMI), infection history, and medical comorbidities" — which is why sentinel node biopsy, sparing the axilla, reduces it.
Causes & risk factors
Modifiable factors are teaching targets — the patient can act on them.
Signs & symptoms
Each finding tied to the mechanism that produces it — and the triage it calls for.
Diagnostics
Complications
Medications for this condition
Why each class is prescribed here — every card links to its full pharmacology page.
Systemic therapy by subtype. Endocrine therapy — "indicated in all hormone receptor-positive patients": tamoxifen (benefit shown in premenopausal HR-positive women; most frequent effect hot flashes; boxed warning for uterine cancer, stroke and PE in the risk-reduction setting) or an aromatase inhibitor such as anastrozole (bone loss, cholesterol rise, arthralgia). Anti-HER2 — trastuzumab for HER2-positive tumors > 1 cm (boxed warning: cardiomyopathy, infusion reactions, embryo-fetal and pulmonary toxicity). Chemotherapy for triple-negative tumors > 1 cm and selected HR-positive disease — NCI flags "Cardiotoxicity from anthracyclines" and "Marrow neoplasia" as toxicities of special concern.
Adjuvant bone-modifying therapy — role uncertain. "Both bisphosphonates and denosumab have been evaluated as adjuvant therapies for early-stage breast cancer; however, their role is unclear."
Post-mastectomy pain — "Multimodal analgesia is recommended to minimize opioid use."
A risk factor, not a treatment — "Some birth control pills can raise breast cancer risk" (CDC).
Beyond medications
- Breast-conserving surgery plus radiation, or mastectomy — BCS is suitable for most tumors < 5 cm; mastectomy for large tumors, skin or chest-wall invasion, multifocal or inflammatory cancer, or when radiation is not possible.
- Sentinel lymph node biopsy for a clinically negative axilla; axillary dissection for clinically positive nodes.
- Post-mastectomy radiation only in selected cases (for example, tumors > 5 cm, chest-wall or skin involvement, or 4 or more positive nodes).
- Complex decongestive therapy for lymphedema — manual lymphatic drainage, multilayer compression bandaging, skin care and decongestive exercises; fitted compression garments, arm elevation and exercise.
- Supervised resistance and aerobic exercise — "Supervised resistance training improves limb function without increasing lymphedema risk."
- Risk reduction for high-risk women — the CDC advises talking with a doctor about "medicines that block or decrease estrogen in your body, or surgery"; BRCA carriers’ relatives can be referred for genetic counseling.
Nursing considerations
The RN-specific layer — each action paired with the reason it matters.
How a real nurse thinks
The clinical-judgment loop, worked for a typical presentation — reasoning, not reference.
- 1 Recognize cues
Within the first 24 hours the drain has put out 160 mL of bright-red blood in 4 hours, the chest wall is swelling and firm, and her heart rate has risen. The BP cuff is on the operative-side arm. She and her daughter have teaching questions.
- 2 Analyze cues
This pattern fits postoperative bleeding with an expanding hematoma — "Most bleeding occurs within 24 hours after surgery," and "ongoing bleeding or larger hematomas require evacuation and hemostasis in the operating room." The BP cuff on the left arm breaks lymphedema risk-reduction advice after axillary dissection. The questions about lifting and screening can be answered from the sources once she is safe.
- 3 Prioritize
Report the bleeding to the surgeon now. Move the BP cuff to the right arm at the same time. Teaching waits until the bleeding is addressed.
- 4 Generate solutions
Notify the surgeon with the drain output, chest-wall findings and vital-sign trend; move the cuff; continue close monitoring of drain output, dressing and vital signs; anticipate a possible return to the operating room. Later: teach lymphedema risk reduction, exercise, and screening for her daughter.
- 5 Take action
SBAR: 54-year-old woman, left mastectomy with axillary dissection at 1400. Drain output 160 mL bright red in 4 hours, chest wall swelling and firm, HR up from 84 to 108, BP 112/70. I am concerned about an expanding hematoma. Requesting urgent evaluation. The cuff is moved to the right arm, and the nursing assistant is told why the left arm is not used for BP or blood draws.
- 6 Evaluate
The surgeon evacuates a hematoma in the operating room; afterwards drain output is low and her heart rate settles. Before discharge she can describe drain care, the no-BP/no-blood-draw rule for her left arm, skin protection, and early lymphedema signs to report, and she knows supervised resistance exercise is safe. Her daughter learns that the USPSTF recommends mammography every 2 years from age 40.
Scenario — you’re the nurse
Work each question before revealing the answer. Rationales explain the wrong options too.
A 54-year-old woman had a left total mastectomy with axillary lymph node dissection at 1400 for a hormone receptor–positive, HER2-positive invasive ductal carcinoma with a clinically positive axillary node. She has a closed-suction drain and a compressive binder.
Q1 Multiple choice At 0200, what is the nurse’s priority? - A. Answer the question about lifting weights
- B. Notify the surgeon about the drain output, chest-wall swelling and rising heart rate
- C. Loosen the compressive binder for comfort
- D. Document and reassess at the next scheduled check
Reveal answer & rationale
Q2 Select all that apply Which instructions help reduce her lymphedema risk? Select all that apply. - A. No blood pressure cuffs or blood draws on the left arm
- B. Keep the skin clean and moisturized and avoid cuts, bites and burns
- C. Avoid hot tubs and saunas
- D. Never lift anything heavier than a few pounds for the rest of your life
- E. Report swelling, heaviness or tight rings on the left side
Reveal answer & rationale
Q3 Multiple choice When is a mastectomy drain generally removed? - A. When output is less than 30 mL over 24 hours
- B. On postoperative day 1 regardless of output
- C. When the drainage turns bright red
- D. Only after all chemotherapy is finished
Reveal answer & rationale
Q4 Select all that apply She will receive trastuzumab. Which nursing actions are correct? Select all that apply. - A. Confirm cardiac function is evaluated before and during treatment
- B. Stop the infusion and get help for anaphylaxis or angioedema
- C. Expect cardiac risk to be greatest when given with anthracyclines
- D. Teach that trastuzumab is safe during pregnancy
Reveal answer & rationale
Q5 Multiple choice Her 41-year-old daughter asks about screening. What does the USPSTF recommend for an average-risk woman her age? - A. Mammography every 2 years starting at 40
- B. Mammography every year starting at 40
- C. Wait until 50 to start
- D. Routine breast MRI every year
Reveal answer & rationale
Common questions
What causes breast cancer?
What are the early signs of breast cancer?
How often should women have mammograms?
Why can’t blood pressure be taken on the arm on the side of breast surgery?
Is breast pain a sign of breast cancer?
What is triple-negative breast cancer?
Sources
- Breast Cancer — StatPearls — StatPearls (NCBI Bookshelf)
- Mastectomy — StatPearls — StatPearls (NCBI Bookshelf)
- Lymphedema — StatPearls — StatPearls (NCBI Bookshelf)
- Breast Cancer Treatment (PDQ®) — Health Professional Version — National Cancer Institute
- Breast Cancer: Screening — Final Recommendation Statement (2024) — U.S. Preventive Services Task Force
- Breast Cancer Symptoms — CDC — Centers for Disease Control and Prevention
- Breast Cancer Risk Factors — CDC — Centers for Disease Control and Prevention
- Tamoxifen citrate tablets — prescribing information (DailyMed) — U.S. FDA / National Library of Medicine
- ARIMIDEX (anastrozole) — prescribing information (DailyMed) — U.S. FDA / National Library of Medicine
- HERCEPTIN (trastuzumab) — prescribing information (DailyMed) — U.S. FDA / National Library of Medicine
Reviewed by Hae Suk Lee, RN
Educational summary for nursing students. Scenarios are fictional teaching cases. Always verify against current guidelines and your institution's protocols before acting in practice. Not medical advice.