Sex steroids and cervical cancer.

During the 19th century, studies indicated that reproductive events were involved in cervical cancer. Human papillomavirus (HPV) infection is a prerequisite for development of cancer, but co-factors, among them the action of sexual steroid hormones, are necessary. Childbirth has been an important risk factor but now probably plays a minor role in the industrialized world, where parity is low. Long-term oral contraceptive use has been thoroughly studied epidemiologically, and correlates to cervical cancer in most studies. In vitro studies on cervical cell lines transfected with HPV and animal studies indicate that sex steroid hormones are capable to induce cancer. In in vivo cervical cancer tissue studies there have been observations that endogenous progesterone in serum correlates to a negative pattern of expression of cellular and extracellular proteins, tumor markers. Immune response could be another mechanism. Estradiol might be associated with a positive pattern and high estradiol and low progesterone levels increase duration of survival in cervical cancer. Studies where treatment of compounds that influence sex steroid hormones have been given are rare and have been disappointing.