A multi-center survey of age of sexual debut and sexual behavior in Chinese women: Suggestions for optimal age of human papillomavirus vaccination in China

Abstract

Objective: Cervical cancer is the second most common cancer among women worldwide, and over 85% of cervical cancers occur in developing countries such as China. Lack of resources for nationwide cervical cancer screening in China makes vaccination against oncogenic strains of HPV particularly important. Knowledge of age at sexual debut and sexual behavior is essential prior to implementation of a national vaccination program. Methods and materials: A cross-sectional epidemiologic survey was conducted across 21 urban and rural sites in China to assess age at sexual debut and sexual behavior. 98.6% of the 11,852 recruited women aged 15–59 years were included in the analysis. Data were collected using a short, nurse-administered questionnaire and analyzed using standard descriptive statistics and survival analysis. Results: In urban areas, more than ten percent of the 15–19 year old age group were already sexually active at the time of interview; this number increased to nearly 44% in the 20–24 year old age group. Chinese young women with an occupation were more likely to be sexually active compared to female students of the same age, irrespective of area of residence. The crude median sexual debut age for the youngest age group was 17 years, earlier than the sexual debut age reported by older cohorts. Younger age cohorts had an earlier menarche age than older cohorts and were more likely to have more sexual partners than older women, and more likely to have partners with more than one female partner. Conclusion: There is a trend towards earlier sexual debut and riskier sexual behaviors in younger age groups of Chinese women. These findings suggest that HPV vaccination of women between the ages of 13 and 15 years, before the completion of national compulsory education, is likely to contribute to the prevention of HPV infection and cervical cancer in China.

Introduction

Cervical cancer is the second most common cancer among women worldwide, with an estimated 529,000 new cases and 275,000 deaths occurring every year [1]. Over 85% of the cases occur in developing countries, where it accounts for 13% of female cancers [1]. In China, wide disparities in cervical cancer incidence and mortality exist, and are mainly attributable to the large population and the unequal economic development in different areas across the country [2]. To date, China does not have an established nationwide program for cervical cancer screening, and the majority of Chinese women have never been screened. This is particularly true for women in rural areas with poor access to health resources [2], [3]. Furthermore, cervical cancer incidence has been increasing in young Chinese women, enlarging the overall burden of the disease in China [4].

Human papillomavirus (HPV) is the most common sexually transmitted virus [5] and is the main cause of cervical cancer [6], [7], [8]. HPV genotypes, or strains, are divided into low-risk and high-risk depending on the spectrum of lesions they induce. The low risk strains cause genital warts and low-grade squamous epithelial lesions, while the high risk, or oncogenic, HPV strains cause lesions that may progress to cervical cancer [8], [9]. Two prophylactic vaccines against the highest-risk strains of human papillomavirus, Gardasil^® (Merck & Co. Inc., Darmstadt, Germany) and Cervarix^®, (GlaxoSmithKline Biologicals, Rixensart, Belgium) have been developed and approved in more than 100 countries around the world [10], [11]. Numerous studies have been published on the efficacy of the vaccines, as well as issues related to policy and implementation in many countries [10], [11], [12], [13]. There is great potential for HPV vaccines to significantly decrease the cervical cancer burden worldwide in generations to come.

Studies of HPV prevalence and incidence indicate that the most consistent predictor of infection is sexual activity, particularly the age of first sexual intercourse, or “sexual debut” [14]. As soon as girls begin having sex, their risk of infection with HPV increases dramatically, so the best vaccination strategy is to reach girls before first exposure. However, to date there are no reliable data on the age of sexual debut in Chinese women, or on the potential differences between women in rural and urban areas, making it difficult to plan for a nationwide HPV vaccination policy. As government approval for the HPV vaccines will likely be forthcoming after the completion of ongoing clinical trials, a comprehensive understanding of the current patterns of age of sexual debut among Chinese women is very important. Such data will help determine the appropriate age for HPV vaccination of Chinese females across the country when the vaccines are adopted in China in the near future. In this paper, we report the average age of sexual debut of Chinese women stratified by urban or rural area and age group.