💊 BRCA1/2 Hereditary Cancer Risk Simulator

Identifying a Pathogenic BRCA1 or BRCA2 Mutation

Genetic testing reveals a pathogenic BRCA mutation, the starting point for risk planning.

• BRCA1/2: Genes tested (DNA repair tumor suppressors)
• Autosomal dominant: Inheritance (50% transmission chance)
• ~1 in 400: Carrier rate (general population, varies by ancestry)
• Sequencing: Test method (blood or saliva sample)

What the test detects

Sequencing finds pathogenic variants disrupting BRCA1/2 repair function.

Why it matters for planning

A positive result reframes future care toward risk-based decisions.

Illustrative educational simulator — not a diagnostic or clinical tool.

General-Population Lifetime Cancer Risk

Baseline risk anchors the comparison before carrier-specific elevation is shown.

• ~12%: Breast cancer, general pop. (lifetime cumulative risk)
• ~1.5%: Ovarian cancer, general pop. (lifetime cumulative risk)
• Age 30+: Typical onset rise (risk accelerates mid-life)
• Gradual: Curve shape (slow cumulative climb)

Reading the baseline curve

Population risk rises slowly, reaching roughly 12% by age 80.

Why this reference matters

Every carrier curve is judged against this population floor.

BRCA Carrier Lifetime Risk, Dramatically Elevated

Untreated carrier risk climbs far above baseline, earlier and much higher.

• ~55–72%: BRCA1 breast risk (illustrative published range)
• ~45–69%: BRCA2 breast risk (illustrative published range)
• ~39–44%: BRCA1 ovarian risk (vs ~1–2% general pop.)
• ~11–17%: BRCA2 ovarian risk (lower, still elevated)

Why risk starts earlier

Repair failure lets damage accumulate from a younger age.

BRCA1 vs BRCA2 magnitude

BRCA1 skews higher overall, especially for ovarian cancer risk.

The gap between curves is the entire rationale for intervention.

Enhanced Surveillance vs Prophylactic Surgery

Two strategies address the same elevated risk very differently in magnitude.

• Detection only: Surveillance effect (earlier catch, same incidence)
• ~90% reduction: Surgery effect (incidence itself falls sharply)
• MRI + mammogram: Surveillance basis (more frequent imaging)
• Mastectomy / RRSO: Surgery basis (removes at-risk tissue)

Surveillance does not lower incidence

More frequent scans catch cancer earlier, not fewer cancers.

Surgery lowers the curve itself

Removing tissue cuts incidence toward the population baseline.

The two strategies act on different parts of the risk curve.

Weighing Risk-Reduction Magnitude Against Surgical Impact

The reduction magnitude differs sharply; the right choice stays personal.

• ~0%: Surveillance reduction (incidence unchanged, earlier catch)
• ~90%: Surgery reduction (toward general-population level)
• Age, family plans: Decision drivers (gene, personal risk tolerance)
• Yes: Pathways combinable (sequential, not exclusive choices)

Comparing the two curves

Surgery flattens the curve; surveillance leaves it unchanged.

A personal, collaborative choice

Genetics teams and patients weigh both paths together.

Neither strategy is universally correct — magnitude is one input among many.