Vaginal delivery and low immunity are strongly associated with high-grade cervical intraepithelial neoplasia in a high-risk population

Is smoking an independent risk factor for developing cervical intra-epithelial neoplasia and cervical cancer? A systematic review and meta-analysis

Introduction: Cervical cancer is the fourth most common form of cancer among women. Smoking tobacco seems to be a risk factor for the development of cervical intra-epithelial neoplasia (CIN) and cervical cancer, but the exact role of smoking in the process of cervical carcinogenesis is not known. The aim of this study is to investigate the relationship between smoking and the development of CIN and cervical cancer. Areas covered: We searched Embase, Medline, Cochrane Central, Web of Science, and Google Scholar for studies on smoking and CIN and cervical cancer, published between 2009 and 2018. The following were the outcomes: CIN3 alone, CIN2 and CIN3 combined, CIN2+, CIN3+, and cervical cancer alone. We included 49 studies in our review and 45 in our meta-analyses. Expert opinion: Based on the available evidence it can be - cautiously - concluded that smoking increases the risk of cervical abnormalities. However, the high risk of bias indicates that for future studies, it will be important to adjust for relevant predictors, to separate CIN from cervical cancer as outcome measures, and to report research methods in detail.

The Influence of Hormonal Factors on the Risk of Developing Cervical Cancer and Pre-Cancer: Results from the EPIC Cohort

BACKGROUND

In addition to HPV, high parity and hormonal contraceptives have been associated with cervical cancer (CC). However, most of the evidence comes from retrospective case-control studies. The aim of this study is to prospectively evaluate associations between hormonal factors and risk of developing cervical intraepithelial neoplasia grade 3 (CIN3)/carcinoma in situ (CIS) and invasive cervical cancer (ICC).

METHODS AND FINDINGS

We followed a cohort of 308,036 women recruited in the European Prospective Investigation into Cancer and Nutrition (EPIC) Study. At enrollment, participants completed a questionnaire and provided serum. After a 9-year median follow-up, 261 ICC and 804 CIN3/CIS cases were reported. In a nested case-control study, the sera from 609 cases and 1,218 matched controls were tested for L1 antibodies against HPV types 11,16,18,31,33,35,45,52,58, and antibodies against Chlamydia trachomatis and Human herpesvirus 2. Multivariate analyses were performed to estimate hazard ratios (HR), odds ratios (OR) and corresponding 95% confidence intervals (CI). The cohort analysis showed that number of full-term pregnancies was positively associated with CIN3/CIS risk (p-trend = 0.03). Duration of oral contraceptives use was associated with a significantly increased risk of both CIN3/CIS and ICC (HR = 1.6 and HR = 1.8 respectively for ≥ 15 years versus never use). Ever use of menopausal hormone therapy was associated with a reduced risk of ICC (HR = 0.5, 95%CI: 0.4-0.8). A non-significant reduced risk of ICC with ever use of intrauterine devices (IUD) was found in the nested case-control analysis (OR = 0.6). Analyses restricted to all cases and HPV seropositive controls yielded similar results, revealing a significant inverse association with IUD for combined CIN3/CIS and ICC (OR = 0.7).

CONCLUSIONS

Even though HPV is the necessary cause of CC, our results suggest that several hormonal factors are risk factors for cervical carcinogenesis. Adherence to current cervical cancer screening guidelines should minimize the increased risk of CC associated with these hormonal risk factors.