Risk factors in invasive cervical cancer among Mexican women.

Objective. To evaluate the association between invasive Cervical Cancer (CC) and high risk Human Papilloma Virus (HR-HPV) (viral load and type 16), along with other gynecological and socioeconomic factors. Material and Methods. Individually matched case-control study (215 women with invasive CC and 420 controls). The study population was recruited between 2000 and 2001. A set of variables traditionally linked with CC (gynecological and socioeconomic factors) and two variables related to HPV infection (viral load and type 16) were assessed. Hybrid Capture II was used to detect HR-HPV DNA. Viral load was measured by light measurements expressed as relative light units (RLU) and they were categorized for analysis into four groups: negative (< 1 RLU), low viral load (1-49 RLU), middle load (50-499 RLU) and high load (> 499 RLU). The analysis included univariate, bivariate and multivariate techniques being the final step the estimation of Odds Ratios (OR) by means of conditional logistic regression models. Results. The probability of having invasive CC was 78 times higher in patients with infection of HR-HPV Risk increases with HPV type 16 (OR=429.7) as compared with other types of HR-HPV (OR=64.1). An important trend was observed with the increase of the viral load (from 46.6 with low viral load; to 250.7 with intermediate and 612.9 with high load). The findings also indicate significant diferences in the viral load between cases and controls according to age groups and HR-HPV types (16 versus others high risk types). Finally, the partner-demographic and obstetrical variables related to the disease increased the risk of invasive CC. No association between CC and smoking was observed in this population. Conclusions. This study helps in identifying women at higher risk of developing invasive CC as a subset of those patients infected with HR-HPV. The findings point strongly to the importance of the viral load in HR-HPV as a cofactor in the development of this disease. This biomarker contributes to improving the prevention and early detection of this disease and also to identify women at higher risk who carry a high viral load of HR-HPV.