Table 1 Characteristics of the included studies
From: Screening for cervical cancer: a systematic review and meta-analysis
Randomized (cluster) controlled trial | |||||||||
|---|---|---|---|---|---|---|---|---|---|
Study | Location | Number of participants | Ages (years) | Screening exposure | Disease definition | Participant eligibility | Post screening treatment | Follow-up | |
Intervention | Control | ||||||||
Sankaranarayanan et al. [20] | India | HPV: 34,126 Cytology: 32,058 | 31,488 | 30 to 59 | Only 8 (<0.007%) of the eligible women had ever been screened | Invasive cervical cancer; FIGO stages I+ | No history of cervical cancer | Cryotherapy, LEEP, conization offered for CIN; invasive cancer referred for treatment (surgery, radiotherapy) | 8Â years 2000 to 2007 |
Cohort studies | |||||||||
Study | Location | Number of participants | Ages (years) | Screening exposure | Disease definition | Participant eligibility | Post screening treatment | Follow-up | |
Herbert et al.[21] | UK | 116,022 (four groups based on screening history) | 25 to 69 | Interval since last smear: <3.5Â y, 3.5 to 5.5Â y, >5.5Â y, no record | Invasive cervical cancer; FIGO stages I+ | No hysterectomy | NR | 3Â years 1991 to 1993 | |
Excluded: smears to investigate symptoms, referral smears in screen-detected cases | |||||||||
Rebolj et al. [22] | Netherlands | Cohort 1: 445,382 Cohort 2: 218,847 | C1: 30 to 44 C2: 45 to 54 | Mean interval between three consecutive negative results | Invasive cervical cancer; FIGO stages NR | Three consecutive negative smears in age interval; no history of CIN or cytological abnormalities | NR | 10Â years 1994 to 2002 | |
C1: 39Â m | |||||||||
C2: 40Â m | |||||||||
Case control studies | |||||||||
Study | Location | Number of participants | Ages (years) | Screening exposure/history | Case/disease definition | Control eligibility | Post screening treatment | Case diagnosis dates | |
Cases | Controls | ||||||||
Andrae et al.[24] | Sweden | 1,230 | 6,124 | 20 to 99 | Interval since last smear: 6 to 42 m (ages <53), 6 to 66 m (ages 54 to 65), 6 to 78 m (ages ≥66), not screened during interval | Invasive cervical cancer; FIGO stages 1+ | No history of cervical cancer; alive on case diagnosis date | NR | 1999 to 2001 |
Excluded: smears <6Â m prior to case diagnosis | |||||||||
Aristizabal et al. [15] | Colombia | 277 | 554 | 16 to 60 | Interval since last smear: 12 to 72Â m prior to case diagnosis | Invasive cervical cancer; excluded in situ | Out-patient services from same clinic where case diagnosed or reside in same area as case | NR | 1977 to 1981 |
Excluded: smears <12Â m prior to diagnosis/index date | |||||||||
Berrino et al.[16] | Italy | 121 | 350 | NR | Interval since last negative smear: 0 to 11 m, 12 to 23 m, 24 to 35 m, 36 to 47 m, 48+ m, no prior negative smear | Invasive cervical cancer; FIGO stages I+ | Married women hospitalized for and diagnosed with non-gynecological diseases; no history of breast cancer or hysterectomy | Two controls had been treated for carcinoma in situ after a positive smear result | 1978 |
Included: smears prior to symptoms (cases), smears prior to study mid-point (controls) | |||||||||
Clarke and Anderson [17] | Canada | 212 | 1,060 | Mean 52 | Interval since last smear: <5Â y prior to case diagnosis | Invasive cervical cancer; most <6Â m post diagnosis | No exclusion for hysterectomy | NR | 1973 to 1976 |
Included: non-symptomatic, routine examination smears | |||||||||
Decker et al.[25] | Canada | 666 | 3,343 | ≥18 Mean 50 | Interval since last smear: <5 y prior to case diagnosis | Invasive cervical cancer; FIGO stages I+ | No history of cervical cancer or malignant neoplasms (excluding non-melanoma skin cancer); no hysterectomy | NR | 1989 to 2001 |
Excluded: smears <6Â m prior to case diagnosis | |||||||||
Hernández-Avila et al. [26] | Mexico | 397 | 1,005 | 25 to 80 Mean 48 | Exposure: any lifetime smear(s), no history | Invasive cervical cancer | Eligibility limited only by age and area of residence | NR | 1990 to 1992 |
Excluded: smears <12Â m prior to case diagnosis or control interview | |||||||||
Herrero et al.[18] | Latin America | 759 | 1,430 | <70 | Interval since last smear: 12 to 23Â m, 24 to 47Â m, never screened | Invasive cervical cancer; FIGO stages I+ | No history of psychiatric diagnoses, hysterectomy, cancer, or diseases related to exposures of interest; history of sexual intercourse | NR | 1986 to 1987 |
Excluded: smears <1Â y prior to interview (mean interval between case diagnosis and: case interview 1Â m; control interview 2.3Â m) | |||||||||
Hoffman et al.[27] | South Africa | 524 | 1,540 | <60 | Interval since last smear: <5 y, 5 to 9 y, 10 to 14 y, ≥15 y, unknown, never | Invasive cervical cancer; FIGO stages IB to IV; diagnosed ≤6 m prior to study enrollment | Hospital admission not related to risk of cervical cancer | NR | NR late 1990s |
Analysis excluding smears in prior 12Â m showed no difference in findings | |||||||||
Jiménez-Pérez and Thomas [28] | Mexico | 143 | 311 | Mean 49 | Interval since last smear: 1 to 12 m, 13 to 60 m, >60 m, unknown, never | Invasive cervical cancer; FIGO stages IB to IV | No hysterectomy; not attending clinic for cervical screening, or any gynecologic or obstetric conditions; history of sexual intercourse | NR | 1991 to 1994 |
Excluded: smears ≤12 m prior to diagnosis/index date | |||||||||
Kasinpila et al.[38] | Thailand | 130 | 260 | Mean 48 | Interval since last smear: <6 m, 6 to 11 m, 12 to 35 m, 36+ m, never | Invasive cervical cancer; diagnosed ≤3 m prior to interview | No evidence of cervical disease or any other gynecological disease | Cryotherapy and LEEP offered for confirmed abnormalities | 2009 |
Excluded: smears in previous 6Â m | |||||||||
La Vecchia et al.[19] | Italy | 191 | 191 | 22 to 74 | Interval since last smear: <3Â y, 3 to 5Â y, >5Â y, never | Invasive cervical cancer; FIGO Stages 1+ | Admitted and diagnosed with acute non-malignant, non-hormonal, non-gynecological problems <1Â y prior to interview | NR | 1981 to 1983 |
Excluded: smears to investigate symptoms; cases with positive smear <1Â y prior to diagnosis | |||||||||
Makino et al. [29] | Japan | 129 | 396 | 35 to 79 | Interval since last negative smear to diagnosis/index date: 1 y, 2 y, 3 y, 4 y, ≥5 y | Invasive cervical cancer; diagnosed <6 m after abnormal smear result | No invasive cervical cancer; no hysterectomy; no previous abnormal cytology results; participated in mass screening | NR | 1984 to 1990 |
Exposure: any lifetime smear(s), no history | |||||||||
Excluded: smears to investigate symptoms or taken at time of diagnosis | |||||||||
Miller et al.[31] | USA | 482 | 934 | Mean 49 | Interval from last negative smear to diagnosis/index date: 1Â y (0 to 18Â m), 2Â y (19 to 30Â m), 3Â y (31 to 42Â m), 3 to 5Â y (42 to 66Â m), 5 to 10Â y (67 to 126Â m), >10Â y (>126Â m) | Invasive squamous cell cervical cancer | No prior hysterectomy or radiation to the pelvis | NR | 1983 to 1995 |
Nieminen et al.[23] | Finland | 179 | 1,507 | 30 to 91 Mean 60 | Exposure: any lifetime smear(s), no history | Invasive cervical cancer | Eligibility limited only by catchment (reside in area served by case treatment hospital) | Organized screening program provides colposcopy examinations and treatment for mild abnormalities | 1987 to 1994 |
Excluded: smears <1Â y prior to diagnosis/index date | |||||||||
Sasieni et al.[32] | UK | 348 | 677 | ≥20 | Interval since last negative smear (not immediately following a test showing abnormal results): 0 to 11 m, 12 to 23 m, 24 to 35 m, 36 to 47 m, 48 to 65 m, >66 m, no history | Invasive cervical cancer; FIGO stages IB+ | No hysterectomy | NR | 1992 |
Sasieni et al.[33] | UK | 1,305 | 2,532 | 20 to 69 | Interval since last negative smear (no abnormal smear in prior 12 m): <3 y, 3<5 y, 5+ y, no history of a negative smear | Invasive cervical cancer; FIGO stages IB+ | No hysterectomy | NR | 1990 to 2001 |
Sasieni et al.[34] | UK | 4,012 | 7,889 | 20 to 69 | Exposure: screening or no screening during specific age bands (for example, 20 to 21, 22 to 24, 20 to 24) related to cancers diagnosed in specific and imminent age bands (for example, 25 to 29) | Invasive cervical cancer; FIGO stages I+ | No hysterectomy; registered with a National Health Services general practitioner, still alive, not emigrated | NR | 1990 to 2008 |
Sasieni et al.[35] | UK | 3,305 | 6,516 | 20 to 69 | Maximum interval between smears: <3.5Â y, 3.5 to 5.5Â y, >5.5Â y or no smear history | Invasive cervical cancer; FIGO stages I+ | No hysterectomy | NR | 1990 to 2008 |
Talbott et al.[30] | USA | 143 | 143 | Mean 45 | Exposure: smear <3Â y prior to case diagnosis or control interview | Invasive cervical cancer (localized, regional or distant); excluded in situ | No hysterectomy | NR | 1984 to 1985 |
Diagnostic smears: any positive result <12Â m prior to diagnosis | |||||||||
Yang et al.[36] | Australia | 877 | 2,614 | 20 to 69 | Exposure: 0, 1 or 2+ smears in last 4Â y | Invasive cervical cancer (localized and non-localized) | No invasive cervical cancer diagnosis 1996 to 2003; alive at case diagnosis; no hysterectomy before end point | NR | 2000 to 2003 |
Excluded: smears <3Â m prior to case diagnosis | |||||||||
Zappa et al.[37] | Italy | 208 | 832 | <70 | Interval since last smear (prior to index date): ≤3 y, 3 to 6 y, 6+ y, no record | Fully invasive cervical cancer; excluded micro-invasive | No hysterectomy prior to index date; alive at index date | NR | 1994 to 1999 |
Excluded: smears <12Â m prior to diagnosis/index date | |||||||||