Breast Cancer Prevention and Screening

Why this matters

Breast cancer remains the most commonly diagnosed cancer in women. Mortality reduction hinges on two levers: lowering risk (primary prevention) and detecting clinically significant disease earlier (secondary prevention). This guide summarizes practical risk assessment, prevention options, and screening strategies that clinicians can implement.

1) Risk Assessment: Who is at increased risk?

• Personal factors: age, prior breast cancer or DCIS/LCIS, atypical ductal/lobular hyperplasia, chest radiation (e.g., mantle radiation) at a young age.
• Family/genetics: early‑onset breast/ovarian/pancreatic/prostate cancers in relatives; known pathogenic variants (BRCA1/2, PALB2, TP53, PTEN, CHEK2, ATM, etc.).
• Reproductive/hormonal: early menarche, late menopause, nulliparity or late first birth, limited/no breastfeeding, prolonged exogenous estrogen/progestin exposure.
• Breast density: heterogeneously or extremely dense breasts raise risk and reduce mammography sensitivity.
• Lifestyle/metabolic: alcohol use, obesity after menopause, physical inactivity, unhealthy diet.

Tools (choose one consistently):
– Tyrer–Cuzick (IBIS) or BOADICEA for lifetime risk and density integration.
– Gail model for 5‑year risk in average‑risk settings (not for strong family history or genetic syndromes).

Risk thresholds that guide care (illustrative):
– ≥20% lifetime risk (model‑based) or pathogenic variant: “high risk” → annual MRI + mammography, consider chemoprevention and risk‑reducing surgery in select cases.
– 5‑year risk ≥3% (or local threshold): discuss chemoprevention.

2) Primary Prevention (risk reduction)

• Lifestyle counseling
• Limit alcohol (≤1 drink/day) or abstain; maintain healthy BMI; 150–300 minutes/week of moderate activity; prioritize plant‑forward diet; encourage breastfeeding when possible.
• Manage cardiometabolic health (glucose, lipids, blood pressure).
• Hormone therapy stewardship
• Use lowest effective dose and shortest duration of menopausal hormone therapy when indicated; avoid in high‑risk patients when alternatives exist.
• Chemoprevention (shared decision‑making)
• Premenopausal: tamoxifen reduces invasive ER+ breast cancer in high‑risk women; discuss VTE and endometrial risks.
• Postmenopausal: tamoxifen, raloxifene, or aromatase inhibitors (anastrozole, exemestane) reduce ER+ cancer risk; balance against vasomotor symptoms, bone effects, VTE.
• Choose based on menopausal status, uterine status, thrombotic and fracture risk, patient preference.
• Genetic counseling/testing
• Indications: strong family history, early‑onset cancers, triple‑negative cancer <60, male breast cancer, Ashkenazi ancestry, known family variants.
• If pathogenic variant: discuss enhanced screening, chemoprevention, and risk‑reducing surgery (see below).
• Risk‑reducing surgery (selected patients)
• BRCA1/2, TP53, and some other high‑penetrance carriers: consider bilateral risk‑reducing mastectomy; risk‑reducing salpingo‑oophorectomy (typically 35–45 years depending on gene and family history) lowers ovarian and, for BRCA2, breast risk.

3) Secondary Prevention (screening)

Screening should match individual risk and breast density, balancing mortality benefit with false positives and overdiagnosis.

Recommended framework (adapt locally):
– Average risk
– Begin routine mammography around age 40–50; interval annual or biennial per guideline and patient preference.
– Continue while life expectancy ≥10 years and patient is willing to undergo treatment if cancer is detected.
– Higher‑than‑average risk (no known pathogenic variant but model‑based ≥20% lifetime risk or prior chest radiation)
– Annual mammography + annual breast MRI (stagger every 6 months if feasible).
– Pathogenic variant carriers (e.g., BRCA1/2, TP53, PALB2)
– Annual MRI starting as early as 25–30; add annual mammography starting 30; consider contrast‑enhanced mammography where MRI unavailable.
– Dense breasts (BI‑RADS C/D)
– Inform patients about decreased mammographic sensitivity. Consider supplemental screening (MRI for high risk; ultrasound or contrast‑enhanced mammography depending on resources and risk).

Modality notes
– Mammography (digital or tomosynthesis) remains foundational for mortality reduction in average‑risk women ≥40.
– MRI offers highest sensitivity; best for high‑risk and dense breast populations.
– Ultrasound is adjunctive, particularly for dense breasts when MRI is not available/appropriate; increases detection but also false positives.

4) Clinical Breast Exam and Self‑Awareness

• Clinical breast exam (CBE): may be offered; evidence for mortality reduction is mixed; can detect interval cancers in some settings.
• Breast self‑exam (BSE): routine, prescriptive BSE has limited mortality benefit; emphasize breast self‑awareness—prompt evaluation of new lumps, focal pain, skin/nipple changes, or spontaneous unilateral bloody discharge.

5) Counseling on Benefits and Harms

• Benefits: reduced mortality, downstaging, less intensive therapy for screen‑detected disease.
• Harms: false positives, anxiety, recalls/biopsies, overdiagnosis (particularly DCIS), radiation exposure (low but cumulative). Use shared decision‑making and provide clear follow‑up plans.

6) Practical workflow checklist (for primary care and women’s health)

1. Document personal/family history; calculate risk with a validated tool; assess breast density from prior imaging.
2. Classify risk tier (average vs higher risk vs pathogenic variant) and select screening plan.
3. Discuss lifestyle changes and, when eligible, chemoprevention (use decision aids).
4. Refer to genetics when criteria met; coordinate MRI scheduling for high‑risk patients.
5. Ensure tracking for recalls, abnormal results, and annual reminders; close the loop.

7) When to refer urgently

• Rapidly enlarging mass; skin edema/dimpling/erythema suspicious for inflammatory breast cancer.
• Spontaneous unilateral bloody nipple discharge.
• Hard, fixed axillary node(s) with or without a breast lesion.

Key takeaways

• Start with risk assessment; align screening with individual risk and density.
• Offer chemoprevention to appropriate high‑risk patients after shared decision‑making.
• Use MRI for high‑risk screening; consider adjuncts for dense breasts.
• Reinforce lifestyle measures that reduce risk and improve overall health.