Assess and manage premalignant lesions of the cervix, including colposcopic assessment

Clinical overview

Cervical premalignancy at this level is about defending a management decision under the twin pressures that define it in South Africa: the largest HIV-driven precancer burden in the world, and a screening programme mid-migration from cytology to HPV-DNA primary testing. The basics are assumed here: the transformation zone and the two stains, HPV carcinogenesis and the LSIL/HSIL terminology, benign mimics of premalignancy, and the SA screening policy and 90–70–90 elimination target. Read those first; this chapter covers the registrar-level decisions — risk-based management, overtreatment, glandular disease, treatment in special populations, and appraising the primary literature behind the algorithm.

The conceptual shift is the move from a test-result paradigm to a risk paradigm. Modern management does not act on a Pap label; it acts on an estimated probability of CIN3+ derived from current and prior results combined. This is the engine of the 2019 ASCCP guidelines, and the central idea in this objective. South African policy applies the same logic with a deliberately pragmatic, single-visit, programme-level overlay because loss-to-follow-up — not test sensitivity — is our rate-limiting failure.

Core knowledge

The two carcinogenic phenotypes, and why subtype changes everything

High-risk HPV drives cervical cancer through E6 (p53 degradation) and E7 (Rb inactivation). The distinction that matters here is that this single mechanism produces two biologically divergent precancers whose detection, treatment and surveillance differ at every step.

• The squamous lineage (CIN/SIL). Arises at the squamocolumnar junction from a discrete population of cuboidal "reserve"/embryonic cells in the original transformation zone. It is visible, contiguous and acetowhite, so colposcopy and ablation work. HPV-16 dominates and is the most transforming genotype — it accounts for the lion's share of squamous cancer and is over-represented in CIN3 relative to its prevalence in low-grade disease, which is why genotype, not cytology grade, best indexes squamous risk. The transformation-zone biology is the reason a Type 3 (endocervical, invisible) TZ forces a different plan: the disease lives where neither stain nor ablation can reach.
• The glandular lineage (AIS → adenocarcinoma). Arises from endocervical columnar epithelium higher in the canal, is HPV-18/45-enriched, and is multifocal with skip lesions. This is not a cosmetic difference: it defeats the three pillars of squamous management. Cytology under-samples it (glandular cells exfoliate poorly and the lesion sits above the os), colposcopy under-reads it (no reliable acetowhite signature, lesions out of view), and ablation cannot treat it (you must have histology and margins). The mechanistic corollary: the rise in cervical adenocarcinoma as a proportion of cervical cancer in HPV-vaccinated and well-screened populations is a screening-failure signature — cytology-based programmes preferentially prevented squamous disease, leaving the glandular fraction behind. HPV-primary screening narrows that gap because 18/45 detection does not depend on exfoliated abnormal cytology.

The genotype anchor is concrete: in ATHENA an HPV-16/18-positive woman carried a 24.4% absolute risk of CIN2+ versus 14.0% for other high-risk types and 0.8% if HPV-negative — which is why 16/18 positivity alone pushes her across the colposcopy threshold regardless of a normal Pap. The corollary, from the ALTS genotype substudy, is the trap: a non-16/18 high-risk-HPV-positive woman is not safe either — her 2-year CIN3+ risk stays ≥7.8%, above the action threshold — so genotype triage escalates 16/18 but does not discharge the rest.

CIN2 is the unstable middle, not a number on a continuum

The clinically load-bearing subtype distinction within squamous disease is that CIN2 is a poorly reproducible, biologically heterogeneous category — a mix of regressing HPV effect and genuine precancer — whereas CIN3 is a reproducible, obligate-treat lesion. This is why p16 immunohistochemistry (the LAST/WHO recommendation) is used to dichotomise an equivocal CIN2 into a low-risk (p16-negative, manage as LSIL) or high-risk (p16-block-positive, manage as HSIL) lesion rather than reflexively excising it. CIN2 in a young woman is the one squamous diagnosis where active surveillance is legitimate because its regression rate is high and cervical-length preservation matters — a judgement that CIN3 never permits.

The risk paradigm and clinical-action thresholds

The 2019 ASCCP Risk-Based Management Consensus Guidelines translate combined results into immediate CIN3+ risk and map that to one of six actions. The excisional thresholds are worth memorising: expedited treatment (treat without a confirmatory colposcopic biopsy) is preferred at an immediate CIN3+ risk of ≥60%, expedited treatment or colposcopy is acceptable at 25–<60%, colposcopy is recommended at 4–<25%, and below that you surveil at 1, 3 or 5 years on the 5-year-risk bands. What matters is not the arithmetic but why this beats a fixed cytology algorithm: it enforces "equal management for equal risk", lets you de-escalate young women with transient infection, and escalates the HPV-16/18-positive woman whose cytology under-reads her disease. The deeper point is what feeds the risk estimate: current result + prior screening history + genotype, so the same HPV-positive/HSIL result carries a different action in a woman with a recent negative HPV history (lower prior, surveil/colposcope) than in one HPV-positive at two consecutive screens (higher prior, toward expedited treatment). A bare Pap label cannot encode that; a risk does.

"Equal management for equal risk" meets a high-prevalence, single-visit system

The WHO 2021 Guideline for screening and treatment of cervical pre-cancer (2nd ed) endorses HPV-DNA as the primary screening test, with a screen-and-treat or screen-triage-treat strategy permitted in the general population, but screen-triage-treat preferred for women living with HIV (WLHIV). Starting ages and intervals diverge by HIV status: general population from age 30, every 5–10 years; WLHIV from age 25, every 3–5 years. South African public-sector policy historically screened HIV-negative women with cytology (three smears, 10-yearly from age 30) and WLHIV at HIV diagnosis and 3-yearly thereafter (2017 NDoH policy); the SASOG/BetterGyn 2024 guideline drives the transition to HPV primary screening with discriminatory genotyping — HPV 16, 18 and 45 carry the highest risk and may be treated without triage, while "other" high-risk types are triaged (cytology/VIA) before treatment. (SA ages/intervals are mid-transition — state the principle and confirm exact bands against the current BetterGyn 2024 / NDoH policy before quoting numbers.)

The consultant-level point is why the WHO permits two paradigms and where SA sits between them. Screen-and-treat (treat every screen-positive without triage) maximises programme completion in a single visit — its entire justification is that in a system losing 30–50% of women to follow-up, a confirmed but untreated CIN3 is more dangerous than the overtreatment of a few HPV-positive women who would have regressed. Screen-triage-treat reintroduces a triage step (cytology, VIA, genotype or colposcopy) to cut that overtreatment, at the cost of a second visit and the attrition it invites. SA's discriminatory-genotyping compromise is the elegant middle: it uses the genotype result already in hand from the primary HPV test (16/18/45 → treat; others → triage) as a triage that costs no extra visit, concentrating immediate treatment on the women whose absolute risk justifies it. The decisive trade-off is loss-to-follow-up versus overtreatment, single-visit versus sensitivity.

The glandular problem: AIS is not "HSIL that happens to be glandular"

Adenocarcinoma in situ (AIS) behaves differently and is a recurring trap. It is multifocal with skip lesions, sits higher in the canal, is poorly detected by both cytology and colposcopy, and is HPV-18/45-driven. Excision (not ablation) is mandatory, and margin status is a dominant predictor of residual disease: negative margins leave roughly 6% residual AIS versus ~50–60% with positive/uninterpretable margins. The squamous-disease caveat: in the Arbyn 2017 meta-analysis (97 studies, 44,446 women) involved margins raised residual/recurrent CIN2+ (RR 4.8), but post-treatment high-risk HPV testing predicted treatment failure more accurately than margin status (sensitivity 91% vs 56%) — so a negative test-of-cure HPV, not a clear margin alone, is the strongest reassurance after squamous excision. For AIS the margin retains particular weight (multifocality, skip lesions, poor surveillance access), so a positive AIS margin still mandates re-excision. Fertility-sparing conisation is acceptable in a woman desiring fertility only with negative margins, negative endocervical sampling, and committed long-term colposcopic surveillance; multiple cones are sometimes needed and a positive margin mandates re-excision, not surveillance. Completed childbearing → simple hysterectomy remains standard.

The technical nuance: for AIS the cone should be a single intact specimen with adequate canal length (a long, narrow "top-hat" or cylindrical cone, not a shallow ectocervical loop), because a fragmented LLETZ specimen makes the margin uninterpretable in a disease where the margin is decisive, and a shallow loop misses canal disease entirely. This is the one premalignant lesion where cold-knife conisation may be preferred over LLETZ — to avoid thermal artefact at the margin in a glandular lesion whose margin must be read.

Assessment

Reading the colposcopy as a risk modifier, not a verdict

Use the systematic colposcopic look and adequacy judgement from Intermediate as the substrate, then integrate it: a Swede/IFCPC high-grade impression in an HPV-16-positive woman raises her risk into the expedited-treatment band; a normal colposcopy in the same woman does not return her to routine screening, because colposcopy misses canal and glandular disease. The TZ type drives the plan: a Type 3 (endocervical, fully invisible) TZ cannot be assessed or ablated and pushes you toward excision and endocervical assessment, especially post-menopausally where the SCJ recedes.

The advanced reading is that colposcopy is an imperfect, operator-dependent test with a known sensitivity ceiling. A single colposcopic biopsy misses a meaningful fraction of CIN3 — sensitivity rises with the number of directed biopsies and with the colposcopist's experience — which is precisely the evidence base for two modern moves: taking multiple targeted biopsies rather than one, and considering non-targeted (random) biopsies of normal-appearing quadrants in a high-risk woman (HPV-16+ or HSIL cytology) with a "normal" colposcopy. It is also why a high-grade cytology with a normal/low-grade colposcopy is discordance that you must resolve — by excision or by repeat assessment — never by reassurance. The grading systems (Reid, Swede, the IFCPC 2011 terminology) are tools to standardise that impression and to communicate it; the Swede score's value is that it makes the size, margin, vessel and iodine-uptake components explicit and so makes "high-grade impression" defensible rather than impressionistic.

Severity and trajectory: what actually escalates the woman

The judgement is integrating four axes into one action, not reading any single result:

• Genotype (16/18/45 vs other high-risk) — the dominant modifier of absolute risk.
• Cytology grade (HSIL/ASC-H/AGC vs LSIL/ASCUS) — with AGC (atypical glandular cells) carrying disproportionate weight because it points at the under-detected glandular compartment and mandates endocervical and endometrial assessment, not just colposcopy.
• Colposcopic impression and TZ type — high-grade impression or a Type 3 TZ shifts toward excision.
• Persistence and prior history — a second consecutive HPV-positive result, or HPV that persists at the same genotype, is a far stronger precancer signal than a single positive.

A persistent same-genotype HPV infection is the single most ominous of these and is the mechanistic reason "repeat in 12 months" exists as an option: transient infection clears, the dangerous one persists, and persistence sorts them. The difficult presentations cluster around the discordances: HPV-positive but cytology-negative (genotype decides), cytology-high-grade but colposcopy-normal (resolve, do not reassure), and the AGC result (hunt the glandular compartment and the endometrium).

The unmissable drill: suspected invasion

Any of — atypical vessels, a friable contact-bleeding lesion, irregular surface, dense acetowhite with coarse mosaic/punctation, or a clinically suspicious cervix — overrides the screening result. A recent negative HPV or "normal Pap" never excludes cancer in a symptomatic woman. Take a directed biopsy (not a LLETZ) when invasion is suspected, and refer to gynae-oncology for examination under anaesthetic, staging and MDT. Failing to do this is the recurrent cause of delayed cervical-cancer diagnosis in audited SA deaths.

The reasoning to make explicit: a LLETZ through an occult invasive cancer is a clinical error, not just a missed diagnosis. It fragments the specimen and destroys the staging information (depth of invasion, lymphovascular space invasion, horizontal spread) that determines whether the woman has a fertility-sparing IA1 lesion or needs radical surgery/chemoradiation — and it can convert a curable early cancer into one disseminated by an inadequate first procedure. A frankly suspicious cervix is therefore a punch-biopsy-then-refer lesion, never a see-and-treat lesion, and the distinction must be drawn before the loop is energised.

Management

Excision vs ablation, and the overtreatment you must not cause

Ablation (thermal ablation, cryotherapy) is permissible only when the whole lesion and SCJ are visible (Type 1/2 TZ), invasion and glandular disease are excluded, and there is no major cytology–colposcopy discordance (WHO ablation eligibility). Everything else — Type 3 TZ, suspected invasion/AIS, recurrence, lesion into the canal, discordance — requires LLETZ/excision so histology and margins are obtained. The trade-off is quantitative: deeper excision lowers treatment failure (laser cone OR 0.59, CKC OR 0.63 vs LLETZ) but raises preterm birth in lockstep (CKC OR 2.27, laser cone 1.77, LLETZ 1.37 vs untreated colposcopy), whereas ablation does not raise preterm birth but fails more often (laser ablation OR 1.69, cryotherapy 1.84 vs LLETZ). LLETZ sits at the balance point for most women; the discipline is to match aggression to risk — lesion size/location, age and future fertility — not to treat every referral with the deepest cone.

Cone depth is a dose: the obstetric harm is in millimetres, not in the modality alone

The key refinement is that the obstetric cost is driven by how much cervix you remove, not merely by which instrument you use — and the relationship is a graded dose-response. The Kyrgiou 2016 BMJ meta-analysis quantifies it against untreated women:

Two operational lessons fall straight out of that table. First, a shallow LLETZ (<10 mm) carries little or no measurable excess preterm-birth risk, which means the harm is largely avoidable by tailoring depth to the TZ type — a Type 1 ectocervical lesion needs a shallow excision, and only a Type 3 canal lesion justifies a deep one. Second, repeat excision is its own dominant risk factor (RR 3.78), so the imperative to get an adequate margin first time in a young woman is partly an obstetric imperative: a second cone for a positive margin compounds the harm. This is the data that converts "be cautious in young women" from a slogan into a number you titrate.

Post-treatment surveillance: HPV test-of-cure and the lifelong tail

Treatment does not end the episode — it opens a surveillance obligation. The modern standard is HPV-based test-of-cure, because Arbyn 2017 showed post-treatment HPV predicts failure far better than margin status (sensitivity 91% vs 56%) and a negative test-of-cure HPV implies only ~0.8% residual risk. The ASCCP schedule is HPV (or co-test) at 6 months, then at intervals, requiring a run of negative tests before the woman returns to a routine interval; a positive test-of-cure HPV at any point returns her to colposcopy. The SA-pragmatic version is the same principle compressed into what the system can deliver — a test-of-cure visit and a low threshold to re-refer — because here the binding constraint is again attendance, not test choice.

The deeper, easily-missed point is the long tail of risk that never fully resolves. Strander's population cohort (BMJ 2007, 80,442 women treated for CIN3) showed a long-lasting roughly two-fold increased risk of invasive cervical and vaginal cancer that accelerates with age, with the relative excess greatest in women treated when older and rising further as they age. The practical consequence is that a woman treated for CIN3 should not be discharged to never-screen-again at the usual cessation age — she carries an above-population risk into old age and warrants continued surveillance beyond the routine programme's stopping point. "Test of cure passed" means "risk reduced, not abolished."

Special populations

• Pregnancy: colposcopy at the same threshold as the non-pregnant woman, but the purpose is only to exclude invasion. Defer treatment of CIN2/3 to ≥6 weeks postpartum — high regression rates plus a vascular cervix make excision in pregnancy hazardous (haemorrhage) and usually unnecessary; biopsy only if invasion is suspected, and re-evaluate postpartum. The advanced caveat: an excisional procedure in pregnancy is reserved for suspected invasion that must be confirmed to direct delivery and oncology planning, is timed to the second trimester if unavoidable, and carries real haemorrhage and pregnancy-loss risk — it is a gynae-oncology MDT decision, not a clinic procedure. See cancer-in-pregnancy for confirmed invasive disease.
• WLHIV: higher incidence, higher multifocality (VAIN/VIN co-disease — inspect the whole lower tract), higher post-treatment recurrence; optimise ART/viral suppression and screen more frequently. Excision is generally preferred over ablation given recurrence risk. The mechanism: HIV-related immunosuppression impairs HPV clearance, so infections persist and progress rather than regress, and the same loss of immune control drives the field effect across cervix, vagina and vulva and the markedly higher recurrence after treatment — which is why ART and viral suppression are part of the cancer-prevention plan, not a parallel concern, and why surveillance is lifelong and more frequent. Treat the precancer, but treat the immune deficit too.
• Adolescents / nulliparous young women: maximise conservatism — CIN2 may be observed in carefully selected young women; preserve cervical length.
• Post-menopause: receded SCJ degrades VIA/colposcopy; a Type 3 TZ lowers your threshold for diagnostic excision.

Contraceptive counselling intersects here: there is no need to stop combined hormonal contraception for CIN, but see contraception-in-high-risk-women when comorbidity coexists.

The SA see-and-treat reality, appraised

South African programme design leans toward single-visit see-and-treat, and the trade-off cuts both ways. The Chris Hani Baragwanath "Look and LLETZ" audit found a low normal-histology (overtreatment) rate of ~1.3% with CIN1/HPV-only in ~8.4% — i.e. acceptable overtreatment in exchange for eliminating the second visit at which a large fraction of women are lost. Set that against TOMBOLA, run in a high-income system with excellent follow-up, which found that immediate colposcopy for low-grade cytology detected more CIN2+ than cytological surveillance but at the cost of overtreatment, and that conservative surveillance was a defensible strategy because attendance could be relied upon. The two trials are not contradictory — they are the same trade-off resolved by context: where loss-to-follow-up is low, you can afford to watch and avoid overtreatment; where it is high, the cost of watching is the cancer you never see again, so you treat. The deciding variable is follow-up reliability.

Landmark trials & key evidence

The studies below underpin screening strategy, treatment choice and the overtreatment trade-off. The numbers matter, not just the conclusions.

Red flags / pitfalls

• Treating a screen, not a risk. Acting on a bare HPV-positive without genotype/triage over-treats transient infection; jumping to LLETZ on low-grade cytology causes the obstetric harm below.
• Quoting fixed SA intervals as settled. Policy is mid-transition (cytology → HPV primary). State the principle; flag the exact bands.
• Applying the HIV-negative schedule to a WLHIV. Serious under-screening; WLHIV screen from diagnosis, more often, lifelong.
• Forgetting AIS. A glandular abnormality, or HSIL that "doesn't fit", demands excision with margins and endocervical sampling — never ablation; and a single intact, adequate-length cone (consider cold-knife) so the margin is readable.
• Reassuring on a negative colposcopy in a symptomatic or high-risk woman. Colposcopy misses canal/glandular disease; resolve high-grade-cytology/normal-colposcopy discordance by excision or repeat, never by reassurance.
• LLETZ-ing a frankly suspicious cervix. Suspected invasion is a punch-biopsy-then-refer lesion — a loop fragments the specimen and destroys the staging that decides fertility-sparing vs radical treatment.
• Excising in pregnancy for premalignancy. Defer to postpartum unless invasion is suspected.
• Over-long cones in young women. Excision depth is the modifiable, dose-dependent driver of later preterm birth (RR 1.54 at <12 mm rising to 4.91 at ≥20 mm); repeat excision (RR 3.78) compounds it — tailor depth to TZ type and get the margin first time.
• Discharging a treated CIN3 at the usual screening-cessation age. The risk is reduced, not abolished, and rises with age — continue surveillance.
• Treating "other" hrHPV-positive minor disease as benign. Genotype triage escalates 16/18(/45); it does not make the rest safe (2-yr CIN3+ risk ≥7.8%).

Worked viva — how to structure the answer

A typical stem: "A 28-year-old WLHIV on ART (suppressed) is HPV-positive, genotype 'other high-risk', cytology HSIL; colposcopy shows a Type 3 transformation zone and a high-grade impression extending into the canal. She wants more children." A high-scoring answer runs:

1. Frame it as risk, not label. "This is a high-grade lesion in a high-risk host — WLHIV with persistent infection and HSIL cytology — and the Type 3 canal-extending TZ is the decisive feature: I cannot fully assess or ablate this, so this is an excision, not a screen-and-treat ablation."
2. Resolve the must-not-miss first. Exclude invasion clinically and colposcopically; the high-grade impression plus canal extension means the excision doubles as the diagnostic specimen — but a frankly suspicious lesion would be punch-biopsy-and-refer instead.
3. Choose the procedure and tailor it. LLETZ/excision with a margin, depth matched to the canal disease but no deeper than needed; counsel that excision depth carries a dose-dependent preterm-birth risk and that a clear margin first time avoids a second cone (the bigger obstetric hit).
4. Treat the host, not just the cervix. Continue ART/viral suppression as part of cancer prevention, inspect the whole lower tract for VAIN/VIN field disease, and plan more-frequent lifelong surveillance.
5. Plan surveillance. HPV-based test-of-cure (Arbyn: HPV beats margin status), re-refer on a positive test-of-cure, and counsel that even a clear result reduces rather than abolishes long-term risk (Strander).
6. Anchor in SA reality. Single-visit see-and-treat where follow-up is unreliable, against the overtreatment it accepts (Bara audit vs TOMBOLA); confirm the exact SA screening bands against current BetterGyn/NDoH policy.
7. Counsel fertility honestly. Treatment is compatible with future pregnancy; the trade-off is a tailored cone depth now versus surveillance she must commit to.

Evidence anchors

• ASCCP 2019 Risk-Based Management Consensus Guidelines (J Low Genit Tract Dis 2020): risk-based, "equal management for equal risk"; expedited treatment preferred ≥60% immediate CIN3+, acceptable 25–<60%, colposcopy 4–<25%; HPV-based test-of-cure surveillance after treatment. The conceptual core of this objective.
• WHO guideline for screening and treatment of cervical pre-cancer lesions, 2nd ed (2021) and its recommendations table: HPV-DNA primary; general population age 30, 5–10-yearly; WLHIV age 25, 3–5-yearly, screen-triage-treat preferred. International scaffold for SA policy.
• SASOG / BetterGyn Clinical Guideline for cervical cancer screening (2024) with the open-access guideline paper and NDoH 2017 Cervical Cancer Prevention & Control Policy: the SA source of truth. HPV primary with discriminatory genotyping (16/18/45 = highest risk, treat-without-triage; others triaged); WLHIV screened at HIV diagnosis, 3-yearly. Confirm exact bands against the current PDF.
• Ronco et al. — pooled European HPV-screening RCTs (Lancet 2014; Swedescreen, POBASCAM, ARTISTIC, NTCC, n=176,464): HPV-based screening gives 60–70% greater protection against invasive cervical carcinoma than cytology (rate ratio 0.60, 95% CI 0.40–0.89), strongest for adenocarcinoma (0.31) and after 2.5 years — the randomised-outcome justification for HPV-primary screening from age 30 with ≥5-year intervals.
• ATHENA / Castle et al. (Lancet Oncol 2011, n≈40,900): HPV testing was far more sensitive for CIN3+ (92.0% vs cytology 53.3%), and HPV-16/18 positivity conferred a 24.4% absolute CIN2+ risk — the validation of partial genotyping behind discriminatory-genotype triage.
• Gage et al. — ALTS genotype substudy (Cancer Epidemiol Biomarkers Prev 2013): HPV-positive but 16/18/45-negative women with minor cytology still had a 2-year CIN3+ risk ≥7.8% — genotype triage escalates 16/18 but does not safely discharge other high-risk types.
• Kyrgiou et al. — obstetric outcomes after CIN treatment (Lancet 2006, 27 studies): the original quantification of obstetric harm — preterm birth CKC RR 2.59 (1.80–3.72), LLETZ RR 1.70 (1.24–2.35), with no significant increase after laser ablation — the evidence base for caution in young women.
• Kyrgiou et al. — adverse obstetric outcomes by cone depth (BMJ 2016;354:i3633): the dose-response — preterm birth rises with depth (<10–12 mm RR 1.54, ≥15–17 mm 2.77, ≥20 mm 4.91) and with repeat treatment (RR 3.78), while excisions <10 mm carry little measurable excess. The basis for tailoring cone depth to the TZ and avoiding repeat cones.
• Arbyn et al. — incomplete excision as predictor of treatment failure (Lancet Oncol 2017, 97 studies, n=44,446): positive margins raise residual/recurrent CIN2+ (RR 4.8, 3.2–7.2; overall failure 6.6%), but post-treatment hrHPV testing predicts failure more accurately than margins (sensitivity 91% vs 56%) — the basis for HPV test-of-cure.
• Athanasiou et al., comparative effectiveness & preterm-birth risk of local CIN treatments — network meta-analysis (PMC full text, Lancet Oncol 2022): the key appraisal piece. Versus LLETZ, treatment failure is lower with laser cone (OR 0.59, 95% CI 0.44–0.79) and CKC (OR 0.63, 0.50–0.81) but higher with laser ablation (1.69) and cryotherapy (1.84); preterm birth versus untreated colposcopy rises with aggression — CKC OR 2.27 (1.70–3.02), laser cone 1.77 (1.29–2.43), LLETZ 1.37 (1.16–1.62), while ablation shows no significant increase. This is the quantitative basis for "match the modality to the risk."
• TOMBOLA Group — cytological surveillance vs immediate colposcopy for low-grade cytology (BMJ 2009;339:b2546, n=4,439): immediate colposcopy detected more CIN2+ but at the cost of overtreatment; surveillance was safe where follow-up was reliable — the appraisal counterpoint to single-visit see-and-treat, with follow-up reliability as the deciding variable.
• Strander et al. — long-term cancer risk after CIN3 treatment (BMJ 2007, population cohort n=80,442): a ~2-fold long-lasting increased risk of invasive cervical and vaginal cancer that accelerates with age — treatment reduces but does not abolish risk; the basis for surveillance beyond routine cessation age.
• DiaVACCS screening trial — Phase I (SAMJ) and test-strategy performance analysis: SA multicentre data driving the HPV-primary transition; confirms near-doubled precancer prevalence in WLHIV.
• "Look and Lletz" — Chris Hani Baragwanath experience: SA see-and-treat audit — single-visit treatment cuts loss-to-follow-up at an acceptable overtreatment cost (normal histology ~1.3%, CIN1/HPV-only ~8.4%). The local-context appraisal anchor.
• WHO thermal-ablation eligibility: ablation only if no suspicion of invasion/glandular disease and the TZ is fully visible (not Type 3). Defines the excision-vs-ablation boundary.