1. Characteristics of the study population
A total of 34,587 women aged 25 - 65 years old attended our hospital for cervical cancer co-screening; 4,198 of these women (12.1%) had hrHPV infection and 1,839 (5.3%) had abnormal cytology results (Figure 1). Multiple HPV infections were detected in 676 of the 4,198 (16.1%) infected women. The most common hrHPV genotype was HPV16 (1,373, 32.7%), followed by HPV58 (680, 16.2%), HPV52 (571, 13.6%), HPV53 (504, 12.0%), HPV33 (360, 8.6%) and HPV18 (301, 7.2%).
2.hrHPV positive women with normal cytology
Of the 4,198 hrHPV infected women, 2,897 (69.0%) women with normal cytology were analyzed in the present study. The mean age of these women was 39.60±8.99 years old, with a median age of 40. The top six hrHPV genotypes were HPV16 (874, 30.2%), HPV58 (452, 15.6%), HPV52 (395, 13.6%), HPV53 (380, 13.1%), HPV18 (224, 7.7%) and HPV33 (208, 7.2%). Regarding each hrHPV genotype, the proportion of women with normal cytology was higher in those infected with HPV59 (76.3%), HPV45 (75.8%), HPV53 (75.4%), HPV18 (74.4%) and HPV51 (70.65%) than other hrHPV genotypes (Table 1).
3. hrHPV genotype and HSIL+ incidence
Colposcopy was performed in 2,665 HPV-positive women with normal cytology. Colposcopy-guided biopsy and random biopsy were carried out in 1,742 (1742/2665, 65.4%) women. A total of 204 women (204/2665, 7.7%) had HSIL+; 173 women (173/2665, 6.5%) had low-grade squamous intraepithelial lesions; and 2,288 women (2288/2665, 85.8%) had negative histology results or normal colposcopy results. Of the 204 women with HSIL+, 26 women (26/204, 12.7%) had ICC (24 cases with squamous cervical cancer and two cases with adenocarcinoma), including 14 women (14/26, 53.8%) who were FIGO stage IA. In the HSIL+ group, the prevalence of the hrHPV genotypes was HPV16 (119, 58.3%), HPV52 (28, 13.7%), HPV58 (26, 12.7%), HPV33 (22, 10.8%), HPV31(15, 7.4%) and HPV18 (12, 5.9%). The percentage of women infected with multiple hrHPV genotypes was 19.1% (39/204) in the HSIL+ group. In the squamous cervical cancer group, the prevalence of HPV16 (18/24, 75%) was prominent. Of the seven cases of adenocarcinoma in situ and adenocarcinoma, five cases were HPV18-positive and two cases were HPV16-positive, including one case of dual infection with HPV18 and HPV33 (Table 1).
4. hrHPV genotypes and detection of histological HSIL+
The proportion of histological HSIL+ in hrHPV positive women with normal cytology who received colposcopy did not differ significantly by age group (divided into 25−34, 35−44, 45−54 and 55−65 years old. P = 0.42). Of the 801 HPV16-positive women with normal cytology who received colposcopy, 119 (119/801, 14.9%) women were confirmed as HSIL+ by histological diagnosis. The proportion of histological HSIL+ in each genotype was greater than10% for HPV16 (14.9%), HPV33 (22/187, 11.8%) and HPV31 (15/142, 10.6%). The proportion of histological HSIL+ in each genotype was less than 10% for HPV52 (28/362, 7.7%), HPV58 (26/414, 6.3%), HPV18 (12/206, 5.8%) and other types. Compared to women infected with HPV16, the proportion of histological HSIL+ was not significantly different in women infected with HPV33 or HPV31 (P = 0.30, P = 0.19, respectively). While HPV58, HPV52, HPV53 and HPV18 were four of the top six most common genotypes in HPV-positive women with normal cytology, the proportion of histological HSIL+ in each of these four HPV genotypes was significantly lower than those in women infected with HPV16 (P < 0.001, P = 0.001, P < 0.001 and P < 0.001, respectively). The proportion of histological HSIL+ in women infected with HPV33 was significantly higher compared to those infected with HPV18 or HPV58 (P = 0.047, P = 0.03, respectively). The differences between the proportion of histological HSIL+ in women infected with HPV18 and those infected with the HPV31, HPV52 or HPV58 were not statistically significant (P = 0.15, P = 0.50, P = 1.00, respectively) (Table 2). The proportion of histological HSIL+ in women infected with multiple genotypes was significantly higher than those with a single infection (P = 0.03) (Table 2).
Among all 2,665 women with hrHPV-positive and cytology-negative results, following adjustment for age, the odds ratio (OR) for histological HSIL+ was 3.75 (95% CI = 2.79−5.05) in women with HPV16 infection, compared to women with non-HPV16 infection. In women infected with HPV33, the OR for histological HSIL+ was 1.69 (95% CI = 1.04−2.72). Infection with HPV genotypes 18, 31, 52 or 58 did not increase the risk of HSIL+ (OR = 0.72, 1.46, 1.03, 0.78, 95% CI = 0.39−1.32, 0.83−2.57, 0.68−1.57, 0.51−1.20, respectively). The OR for histological HSIL+ was 3.26 (95% CI = 2.41−4.40) in women with HPV16/18 infection. The OR for histological HSIL+ was 4.21 (95% CI = 2.99−5.93) in women infected with HPV16/18/31/33. The OR for histological HSIL+ was 5.73 (95% CI = 3.30−9.97) in women infected with HPV16/18/31/33/52/58 (Table 3).
HPV16/18 infection was detected in 129 of 204 (63.2%) women with histological HSIL+; by contrast, the top six hrHPV genotypes (HPV16/18/31/33/52/58) in the HSIL+ group were detected in 190 (190/204, 93.1%) women. However, the colposcopy per HSIL+ detection ratio also increased significantly from 7.7 to 10.2 (P = 0.01). Adding the HPV31/33 genotype to the HPV16/18 genotype increased the percentage of HSIL+ detection from 63.2% to 77.5% (P = 0.002) without significantly increasing the colposcopy per HSIL+ detection ratio (7.7 to 8.1, P = 0.66). (Table 3).