Co-factors of high-risk human papillomavirus infections display unique profiles in incident CIN1, CIN2 and CIN3

Ranking lifestyle risk factors for cervical cancer among Black women: A case-control study from Johannesburg, South Africa

BACKGROUND

Aside from human papillomavirus (HPV), the role of other risk factors in cervical cancer such as age, education, parity, sexual partners, smoking and human immunodeficiency virus (HIV) have been described but never ranked in order of priority. We evaluated the contribution of several known lifestyle co-risk factors for cervical cancer among black South African women.

METHODS

We used participant data from the Johannesburg Cancer Study, a case-control study of women recruited mainly at Charlotte Maxeke Johannesburg Academic Hospital between 1995 and 2016. A total of 3,450 women in the study had invasive cervical cancers, 95% of which were squamous cell carcinoma. Controls were 5,709 women with cancers unrelated to exposures of interest. Unconditional logistic regression models were used to calculate adjusted odds ratios (ORadj) and 95% confidence intervals (CI). We ranked these risk factors by their population attributable fractions (PAF), which take the local prevalence of exposure among the cases and risk into account.

RESULTS

Cervical cancer in decreasing order of priority was associated with (1) being HIV positive (ORadj = 2.83, 95% CI = 2.53-3.14, PAF = 17.6%), (2) lower educational attainment (ORadj = 1.60, 95% CI = 1.44-1.77, PAF = 16.2%), (3) higher parity (3+ children vs 2-1 children (ORadj = 1.25, 95% CI = 1.07-1.46, PAF = 12.6%), (4) hormonal contraceptive use (ORadj = 1.48, 95% CI = 1.24-1.77, PAF = 8.9%), (5) heavy alcohol consumption (ORadj = 1.44, 95% CI = 1.15-1.81, PAF = 5.6%), (6) current smoking (ORadj = 1.64, 95% CI = 1.41-1.91, PAF = 5.1%), and (7) rural residence (ORadj = 1.60, 95% CI = 1.44-1.77, PAF = 4.4%).

CONCLUNSION

This rank order of risks could be used to target educational messaging and appropriate interventions for cervical cancer prevention in South African women.

Risk Factors for Non-Human Papillomavirus (HPV) Type 16/18 Cervical Infections and Associated Lesions Among HPV DNA-Negative Women Vaccinated Against HPV-16/18 in the Costa Rica Vaccine Trial

BACKGROUND

Factors that lead human papillomavirus (HPV) infections to persist and progress to cancer are not fully understood. We evaluated co-factors for acquisition, persistence, and progression of non-HPV-16/18 infections among HPV-vaccinated women.

METHODS

We analyzed 2153 women aged 18-25 years randomized to the HPV-vaccine arm of the Costa Rica HPV Vaccine Trial. Women were HPV DNA negative for all types at baseline and followed for approximately 11 years. Generalized estimating equation methods were used to account for correlated observations. Time-dependent factors evaluated were age, sexual behavior, marital status, hormonally related factors, number of full-term pregnancies (FTPs), smoking behavior, and baseline body mass index.

RESULTS

A total of 1777 incident oncogenic non-HPV-16/18 infections were detected in 12 292 visits (average, 0.14 infections/visit). Age and sexual behavior-related variables were associated with oncogenic non-HPV-16/18 acquisition. Twenty-six percent of incident infections persisted for ≥1 year. None of the factors evaluated were statistically associated with persistence of oncogenic non-HPV-16/18 infections. Risk of progression to Cervical Intraepithelial Neoplasia grade 2 or worst (CIN2+) increased with increasing age (P for trend = .001), injectable contraceptive use (relative risk, 2.61 [95% confidence interval, 1.19-5.73] ever vs never), and increasing FTPs (P for trend = .034).

CONCLUSIONS

In a cohort of HPV-16/18-vaccinated women, age and sexual behavior variables are associated with acquisition of oncogenic non-HPV-16/18 infections; no notable factors are associated with persistence of acquired infections; and age, parity, and hormonally related exposures are associated with progression to CIN2+.

Updating the natural history of human papillomavirus and anogenital cancers

This chapter addresses the natural history of anogenital human papillomavirus (HPV) infection. Cervical infections are the best understood HPV infection. Cervical HPV persistence is the known necessary event for the development of cervical cancer. New infections appearing at any age are benign unless they persist. Several long-term natural history studies have now shed light on the very low risk of cervical intraepithelial neoplasia (CIN) 3+ in women past the peak of HPV acquisition (e.g., 30 or older) who are HPV-negative or clear their HPV. Although data on transmission of HPV are finally emerging, rates of transmission between heterosexual couples vary widely among studies. Factors that affect the calculations of these rates include a) intervals between testing points, b) rates of concordance or discordance at baseline, and c) difficulty in defining established infections versus contamination. Both cervix to anus and anus to cervix autoinoculation in the same woman appears to be quite common. Whether either site serves as a long-term reservoir is unknown. Studies show that anal infections in women and in men who have sex with men are quite common with cumulative rates up to 70-90%. Similarly, clearance of anal HPV is also common, with few individuals showing persistence unless they are human immunodeficiency virus (HIV)-infected. HIV strongly influences the development of anal intraepithelial neoplasia (AIN). The few studies on the natural history of AIN in HIV-infected men suggest that high-grade AIN is a precursor to invasive anal cancer. Although no natural history studies of AIN are available in women, women with other HPV-associated lesions, including CIN3+ and vulvar cancer, have higher rates of anal cancer. Data on the natural history of HPV of the male genitalia are also emerging, although penile intraepithelial neoplasia is poorly understood. Cumulative rates of HPV are extremely high in men and risks are associated with sexual behavior. Unlike women, prevalence rates are steady across all ages, suggesting that men do not develop protection against reinfection. This article forms part of a special supplement entitled "Comprehensive Control of HPV Infections and Related Diseases" Vaccine Volume 30, Supplement 5, 2012.

The role of co-factors in the progression from human papillomavirus infection to cervical cancer

OBJECTIVE

Co-factors for cervical cancer, including oral contraceptive (OC) use, smoking and multiparity have been identified; however, the stage at which they act in cervical carcinogenesis is not clear. We compared established risk factors among women with CIN2 and CIN3 to evaluate the heterogeneity of these factors in precancer and also assessed their role during cervical carcinogenesis.

METHODS

The current analysis included 2783 women with various stages of cervical disease who were enrolled in the Study to Understand Cervical Cancer Early Endpoints and Determinants (SUCCEED) and the Biopsy Study. Associations of co-factors within cervical precancer and at different stages of cervical carcinogenesis were estimated using logistic regression.

RESULTS

Long-term OC use (10+years vs. never: OR=2.42, 95% CI: [1.13-5.15]), multiparity (3+ births vs. nulliparous: OR=1.54 [1.04-2.28]), smoking (ever vs. never: OR=1.95 [1.48-2.58]), and no Pap test in the previous five years (2.05 [1.32-3.17]) were positively associated with CIN3 compared to CIN2. We observed that long-term OC use, parity and smoking were associated with an increased risk of CIN3 compared to <CIN2 (1.97 [1.12-3.46]; 2.23 [1.59-3.11]; 2.60 [2.04-3.30], respectively), whereas associations were not significantly different (OC use, parity) or showed decreased risk (smoking) when comparing cancer to CIN3.

CONCLUSIONS

Differences in established risk factors suggest that CIN3 is a more specific definition of precancer than CIN2. Hormonally-related factors and smoking play a role in the transition from human papillomavirus infection to precancer.