Abstract
It is valuable to establish a population‐based prevaccination baseline distribution of human papillomavirus (HPV) types among women with high‐grade cervical intraepithelial neoplasia (CIN) grade 2 or 3 and cervical cancer in order to assess the potential impact of HPV vaccination. In four countries (Denmark, Norway, Sweden, and Iceland), we collected consecutive series of cervical cancers (n = 639) and high‐grade precancerous cervical lesions (n = 1240) during 2004‐2006 before implementation of HPV vaccination and subjected the specimens to standardized HPV genotyping. The HPV prevalence was 82.7% (95% confidence interval [CI] 79.0‐86.4) in CIN2, 91.6% (95% CI 89.7‐93.5) in CIN3, and 86.4% (95% CI 83.7‐89.1) in cervical cancer. The most common HPV types in CIN2/3 were HPV16 (CIN2: 35.9%, 95% CI 31.2‐40.6; CIN3: 50.2%, 95% CI 46.8‐53.6) and HPV31 (CIN2: 10.9%, 95% CI 7.8‐13.9; CIN3: 12.1%, 95% CI 9.9‐14.3), while HPV16 and HPV18 were the most frequent types in cervical cancer (48.8%, 95% CI 44.9‐52.7 and 15.3%, 95% CI 12.5‐18.1, respectively). The prevalence of HPV16/18 decreased with increasing age at diagnosis in both CIN2/3 and cervical cancer (P < 0.0001). Elimination of HPV16/18 by vaccination is predicted to prevent 42% (95% CI 37.0‐46.7) of CIN2, 57% (95% CI 53.8‐60.5) of CIN3 and 64% (95% CI 60.3‐67.7) of cervical cancer. Prevention of the five additional HPV types HPV31/33/45/52/58 would increase the protection to 68% (95% CI 63.0‐72.2) in CIN2, 85% (95% CI 82.4‐87.2) in CIN3 and 80% (95% CI 77.0‐83.2) in cervical cancer. This study provides large‐scale and representative baselines for assessing and evaluating the population‐based preventive impact of HPV vaccination.
Highlights
More than 500 000 women are diagnosed every year with cervical cancer, and around 260 000 women die, making it the fourth most common cancer in women.[1]
A few samples had only nononcogenic human papillomavirus (HPV) types (CIN2: 5.2%, 95% CI 3.0‐7.4 and CIN3: 1.6%, 95% CI 0.7‐2.4)
The most prevalent HPV type was HPV16 in CIN2/3 were HPV16 (CIN2) (35.9%, 95% CI 31.2‐40.6 among all and 43.4%, 95% CI 38.1‐48.8 among HPV positive) and CIN3 (50.2%, 95% CI 46.8‐53.6 among all and 54.8%, 95% CI 51.3‐58.4 among HPV positive)
Summary
More than 500 000 women are diagnosed every year with cervical cancer, and around 260 000 women die, making it the fourth most common cancer in women.[1] Normal cervical epithelium may develop through high‐grade cervical intraepithelial neoplastic (CIN) lesions into cervical cancer. This transition requires persistent infection with oncogenic types of human papillomavirus (HPV),[2] of which HPV16 and 18 have the greatest oncogenic potential.[3,4] Together, HPV16/18 causes approximately 70% of cervical cancer.[3,4]. Previous studies have reported a higher prevalence of HPV16/18 with increasing severity of cervical lesions.[10,11] only few studies have examined the age‐specific distribution of HPV types among population‐based series of women with either cervical cancer or high‐grade precancerous cervical lesions.[4,13,14]
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