Table 1.

Characteristics of 738 participants used in first smear analyses

CharacteristicCIS cases (N = 375), n (%)Controls (N = 363), n (%)P*
Matching variables
    Age at first smear (y)
        ≤2038 (10.1)35 (9.6)
        20-25116 (30.9)113 (31.1)
        26-30113 (30.1)111 (30.6)
        >30108 (28.8)104 (28.6)
    No. years between first smear and diagnosis
        <5130 (34.7)123 (33.9)
        5-967 (17.9)76 (20.9)
        10-1487 (23.2)77 (21.2)
        ≥1591 (24.3)87 (24.0)
Other risk factors
    Marital status at diagnosis
        Married278 (74.1)281 (77.4)0.71
        Unmarried43 (11.5)41 (11.3)
        Divorced39 (10.4)31 (8.5)
        Widowed15 (4.0)10 (2.8)
    Education (y) at diagnosis
        6-9114 (30.4)88 (24.2)0.18
        10-12102 (27.2)107 (29.5)
        ≥13159 (42.4)164 (45.2)
        Missing01 (1.1)
    Oral contraceptive use at first smear
        Never/prior153 (40.8)180 (49.6)0.01
        Current222 (59.2)183 (50.4)
    Parity at first smear
        Nulliparous141 (37.6)180 (49.6)<0.001
        1101 (26.9)71 (19.6)
        2100 (26.7)73 (20.1)
        ≥333 (8.8)39 (10.7)
    Age at sexual debut (y)
        ≤1592 (24.5)92 (25.3)0.55
        16-17154 (41.1)136 (37.5)
        18-1991 (24.3)84 (23.1)
        ≥2038 (10.1)51 (14.0)
    No. sexual partners at first smear
        0-166 (17.6)103 (28.4)<0.001
        2-3130 (34.7)125 (34.4)
        4-585 (22.7)75 (20.7)
        ≥594 (25.1)60 (16.5)
  • * P values adjusted for age at first smear and number of years between first smear and diagnosis.

  • Current, within 2 years before the smear date.