Human Papillomavirus and Other Relevant Issues in Cervical Cancer Pathogenesis

Cancer of the uterine cervix (cervical cancer) is a leading cancer among women worldwide, although its incidence has been reducing in many developing nations. In the majority of cervical cancer cases, the presence of high-risk human papillomavirus (HPV) is usually detected. However, a growing body of evidence currently considers that exclusive HPV infection may not be sufficient for cancer development. Apart from certain common risk factors for cervical cancer, like poor nutritional status and smoking, many studies documented an association with other viral infections, such as human immunodeficiency virus (HIV) and herpes simplex virus type 2 (HSV-2). Similarly, vaginal bacterial populations perhaps play a key role in cervical cancer. It may be worth mentioning that different bacterial species can immensely influence (either protecting or adversely) the biochemical characteristics of the cervicovaginal environment-for example, Lactobacillus crispatus, Gardnerella vaginalis, and Chlamydia trachomatis. As a result, chronic infections with unfavorable microorganisms (other than HPV) may affect the pathological processes of malignancy. On the other hand, the cervix is an estrogen-sensitive organ like the corpus uteri (i.e., the body of the uterus). Estrogen and different estrogen receptors are implicated in the development and promotion of various cancers, including endometrial cancer. A number of reports also suggest a close association between estrogen and HPV in the development of cervical cancer. Furthermore, estrogen is linked with the characteristics of the vaginal microenvironment including bacteria. Therefore, several of the abovementioned factors (some are preventable) could play an important role in the progression of cervical neoplastic lesions.