12-phase flow (12)

1. 1FRAME
   Confirm preventive screening scope: asymptomatic adult, life expectancy ≥10 yr (below which lead-time + overdiagnosis harm > benefit → STOP-screening). Excludes diagnostic workup of known symptoms/lesions and prior-cancer survivorship surveillance (USPSTF 2021; ACS 2018)
   inputs: age, sex_assigned_at_birth, life_expectancy_estimate
   advance: Asymptomatic, eligible, ≥10-yr life expectancy confirmed
2. 2ENTRY
   Trigger: routine wellness visit, overdue/never-screened flag, high-risk syndrome referral, risk-model expansion, or positive-screen follow-up (USPSTF 2021)
   advance: Entry trigger captured
3. 3CONTEXT
   Establish the pre-test prevalence prior: age, sex, smoking pack-years, family cancer history, genetic syndromes, prior screening dates/results, HPV vaccination, cirrhosis/HBV, breast density, pregnancy, prior-cancer status (USPSTF 2021/2024; ACS 2018; AASLD 2023). This phase SETS the Bayesian prior — modality choice flows from it
   inputs: age, sex_assigned_at_birth, family_hx_cancer, prior_screening_results, cirrhosis_status, chronic_hbv, hpv_vaccination_status, pregnancy_status, prior_cancer_survivor
   advance: Pre-test prevalence tier assignable per cancer type
4. 4RED_FLAGS
   Hereditary cancer syndromes (very high prior): Lynch (MLH1/MSH2/MSH6/PMS2 — CRC lifetime up to ~50-80%), BRCA1/2 (breast ~55-72% lifetime), Li-Fraumeni (TP53), FAP (APC, near-100% CRC) → genetics referral + NCCN intensified protocol; cascade family testing. New suspicious symptoms exit to the relevant diagnostic engine (NCCN 2024)
   inputs: genetic_syndrome
   actions: workup.genetic_counseling
   advance: High-risk syndromes flagged or excluded
5. 5INITIAL_WORKUP
   Order the age/sex/risk-appropriate screen — the test with its fixed characteristics: LDCT (NLST 20% mortality RR; Lung-RADS), mammography (sens density-dependent; BI-RADS), hrHPV/cytology (hrHPV sens ~90-95%), colonoscopy/FIT/FIT-DNA/CTC, shared-decision PSA (low spec), AFP + US HCC q6mo (AASLD 2023). Each order is the "treatment" (USPSTF 2021/2024/2018; AASLD 2023)
   inputs: smoking_history_pack_years, psa, afp, liver_ultrasound
   actions: workup.lung_screening_ldct, workup.breast_screening_mammogram, workup.cervical_screening_hpv_pap, workup.colorectal_screening, workup.prostate_screening_psa, workup.hcc_surveillance, panel.psa, panel.afp, panel.hpv_genotyping
   advance: All indicated screening tests ordered with shared-decision documented where required (PSA, LDCT)
6. 6BRANCHING_WORKUP
   Positive-screen Bayesian follow-up — apply PPV to the structured category: Lung-RADS 3/4 → short-interval CT or PET/biopsy (Lung-RADS 4 PPV >15%); BI-RADS 4/5 → biopsy (BI-RADS 5 PPV >95%); positive FIT/FIT-DNA → diagnostic colonoscopy; hrHPV 16/18+ → colposcopy; elevated PSA → mpMRI/PI-RADS reflex before biopsy; suspicious liver lesion → LI-RADS multiphasic CT/MRI; supplemental breast MRI if dense + Tyrer-Cuzick ≥20% (ACR Lung-RADS 2022; ACR BI-RADS; USMSTF 2017; ASCCP 2019; AUA 2023; AASLD 2023)
   inputs: breast_density, fit_result, hrhpv_result
   actions: workup.lung_nodule_followup, workup.breast_biopsy, workup.colonoscopy_diagnostic, workup.prostate_mri_biopsy, workup.hcc_diagnostic_ct_mri
   advance: Every positive screen has a PPV-appropriate follow-up route
7. 7DIFFERENTIAL
   Average-risk vs high-risk pathway, AND true-positive (early cancer) vs false-positive (benign nodule, inflammatory polyp, dense-tissue artifact, BPH-driven PSA) — the false-positive cascade and overdiagnosis are encoded as harm data, not prose. Screen-detected positive routes to the dx engine; screen-negative returns to interval (USPSTF 2021; NLST FP 96.4%)
   advance: Each result classified as average/high-risk and true/false-positive likelihood assigned
8. 8RISK_STRATIFICATION
   Risk-model scoring sets the prior tier and the action threshold: PLCOm2012 6-yr ≥1.3-1.7% expands LDCT eligibility beyond pack-year rule (Tammemägi NEJM 2013); Tyrer-Cuzick/IBIS lifetime ≥20% → add MRI (ACR 2023); Gail/BCRAT 5-yr ≥1.67% → chemoprevention discussion (USPSTF 2019); GALAD for HCC in cirrhosis (AASLD 2023); average vs high-risk CRC by family hx / Lynch / FAP / IBD (USMSTF 2017)
   inputs: smoking_history_pack_years, family_hx_cancer, cirrhosis_status, chronic_hbv, chest_radiation_history
   actions: calc.plco_m2012, calc.tyrer_cuzick, calc.gail_model, calc.galad_score
   advance: Risk tier + action threshold assigned per cancer type
9. 9TREATMENT
   The screen IS the intervention; document shared decision-making (PSA — USPSTF 2018; LDCT — USPSTF 2021). Chemoprevention where threshold met: tamoxifen/raloxifene/exemestane if Gail 5-yr ≥1.67% (USPSTF 2019); HPV vaccination catch-up through age 26 (ACIP 2019). Integrate smoking-cessation pharmacotherapy into every lung screen (the benefit of LDCT is conditional on cessation)
   inputs: family_hx_cancer
   advance: Screen ordered, shared decisions documented, chemoprevention/vaccination considered
10. 10DISPOSITION
    All screening is ambulatory; positive screens route to the specific diagnostic engine/specialty: lung nodule → pulmonology/onc.lung-cancer.core.v1; BI-RADS 4-5 → breast surgery; positive FIT/advanced adenoma → GI; PSA → urology; LI-RADS 4-5 → hepatology/gi.hcc.core.v1; confirmed syndrome → NCCN high-risk protocol (USPSTF 2021; NCCN 2024)
    advance: Disposition + specialist routing documented
11. 11MONITORING
    Interval + recall: LDCT annually while eligible 50-80 (USPSTF 2021); mammography biennially 40-74 (USPSTF 2024); cytology q3yr 21-29, hrHPV q5yr or co-test q5yr 30-65 (USPSTF 2018; 2025 WPSI hrHPV-primary preferred 30-65); colonoscopy q10yr / FIT annual / FIT-DNA q1-3yr / CTC q5yr (USPSTF 2021); PSA q1-2yr 55-69 if shared decision to screen (USPSTF 2018); AFP + US q6mo in cirrhosis (AASLD 2023); post-polypectomy surveillance per USMSTF 2020 risk strata
    advance: Next-screen dates set + recall scheduled
12. 12FOLLOWUP
    STOP-screening / survivorship logic (the deprescribing-equivalent): discontinue when life expectancy <10 yr, age exceeds the upper bound (mammo >74, CRC >85, cervical >65 with adequate prior negatives, PSA ≥70, LDCT after 15 yr quit or curative-surgery-ineligible, HCC if not transplant/treatment candidate). Patient education on false-positive rate (LDCT 96.4% over 3 rounds — NLST), overdiagnosis (mammography ~10-20%, prostate substantial), and the value of NOT screening when harm dominates (USPSTF 2021; ACS 2018)
    inputs: life_expectancy_estimate
    advance: Stop-screening decision OR continued-interval education delivered and documented