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Liquid-Based Cytology and Human Papillomavirus Testing to Screen for Cervical Cancer

Appendix Table. Characteristics of Randomized, Controlled Trials of HPV Screening Strategies for Cervical Cancer Screening

Variable Study (Reference)
NTCC Phase II (39) Finnish Trial (45, 51) NTCC Phase I (46) POBASCAM (47) Swedescreen (49, 50) ARTISTIC (48)
Total randomized and screened, n 49,196 71,337 45,174 44,938 12,527 24,510
Ages recruited, y 25–60 25–65 25–60 30–56 32–38 20–64
Older women, n 35,471 59,757 33,364 44,938 12,527 19,344
Number of screening rounds 2 1 2 2 2 2
Round interval, y 3 2–4 3 5 3 3
Follow-up, y 3.5* Mean, 3.3 3.5* 6.5 Mean, 4.1 7§
Screening approach
Round 1 HC2 vs. CC HC2 with cytology triage (CC) vs. CC HC2 + LBC vs. CC PCR + CC vs. CC PCR + CC vs. CC HC2 + LBC vs. LBC
Round 2 CC vs. CC NA CC vs. CC PCR + CC vs. PCR + CC PCR + CC vs. CC HC2 + LBC vs. LBC
Treatment threshold CIN2+ CIN1+
CIN2+||
CIN2+ NR High-grade CIN CIN2+
Treatment NR LEEP NR NR Conization, loop excision Excision, ablation
USPSTF quality rating Fair Fair Fair Fair Fair Fair
Quality and interpretation issues Participants were not blinded.

Cytology may be relatively poor if laboratory standards among the 14 that performed the analyses differ. Colposcopists and local histologists were not blinded to HPV results, but there was blinded central review of diagnosis.

Community colposcopy was repeated if normal but "clearly abnormal cytology"; no biopsies were done in negative colposcopy.

Noncompliant women in round 1 were not invited to round 2 (2.8% in IG vs. 0.7% in CG).

Different tests in round 1 and round 2: HC2 vs. CC in round 1, CC vs. CC in round 2.

Does not exclude women with CIN2+ in round 1 from round 2.

Cytology referral threshold differed by site.

Single screening round, but extended 5-year follow-up.

Cytologist, colposcopists, and pathologists were not blinded to HPV results; community colposcopy; no biopsies were done in normal colposcopy.

Randomization scheme was not reported.

Eligibility (other than age) was not clear.

Cytology may be relatively poor if community standards are not good, especially for LBC (14 labs); blinded to HPV.

Colposcopists and histologists were not blinded to HPV results.

Community colposcopy was repeated if normal but "clearly abnormal cytology"; no clear biopsies done in negative colposcopy.

Noncompliant women in round 1 were not invited to round 2 (2.7% in IG vs 0.6% in CG).

Different tests in round 1 and round 2: HC2 vs. CC in round 1, CC vs. CC in round 2.

Does not exclude women with CIN2+ in round 1 from round 2.

Cytology referral threshold differed by site.

Round 2 results for two thirds of the sample were still not reported.

Blinding was reported for cytology and HPV results but not for participants or histology. 5-y interval between rounds (3 in most trials).

59% of participants had not completed 6.5 y of follow-up at the time of analysis.

For both round 1 and round 2, data were reported only for those completing all 6.5 y of follow-up.

In round 2, all women received both HPV and CC.

Cytology reading was not described; patients were unblinded to HPV at year 3 owing to high CIN2+/3+ in those who were HPV-positive.

Round 2 follow-up is limited to 1 y; does not include retesting results.

Number of women with incomplete follow-up was not quantified.

Round 2 occurs outside study, with registry data only.

Referral threshold differed by site (about one half ASC-US+, one half HSIL+).

Colposcopists were aware of HPV+/cytology− results.

No biopsies in negative colposcopy.

Round 2 data ignored CIN2+ histology after normal cytology to make diagnostic criteria the same in both arms—reduces impact of retesting (HPV+/cyto−).

Interval between round 1 and round 2 ranged from 26 to 54 mo.

Excludes women with CIN2+ from subsequent rounds.

Incomplete round 2 follow-up (34% not attending round 2 at time of analysis).

Maximum follow-up from baselineof 7 y; mean follow-up NR.

Histology follow-up in round 2 after screening shortened (<30 mo) for 29%.

ASC-US = atypical squamous cells of undetermined significance; CC = conventional cytology; CIN = cervical intraepithelial neoplasia; HC2 = Hybrid Capture 2; HPV = human papillomavirus; HSIL = high-grade squamous intraepithelial lesion; LBC = liquid-based cytology; LEEP = loop electrosurgical excision procedure; LSIL = low-grade squamous intraepithelial lesion; NTCC = New Technologies for Cervical Cancer Screening; PCR = polymerase chain reaction; USPSTF = U.S. Preventive Services Task Force.
* NTCC Phase I and NTCC Phase II, maximum follow-up after invitation to Round 2 reported.
Follow-up among a subset of the population.
Median follow-up years between enrollment and colposcopy.
Maximum follow-up reported.
|| Treatment method varied by date and age.
Treatment method varied by site.

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