Risk of cancer development in relation to oral contraception

An update on contraceptive therapy options

The introduction of new contraception formulations and different routes of administration offers women more options when choosing birth control methods. Despite new options, there are still risks to consider when prescribing contraception to women on an individual basis. In the past 5 years alone, there has been the introduction of extended and continuous cycle oral contraceptives, a new subdermal implant, and shorter hormone-free intervals in 28-day cycles. Cardiovascular risks including stroke, myocardial infarction, and venous thromboembolism are risks that must still be considered in certain populations. In 2005, the Food Drug and Administration issued a press release concerning the higher exposure to estrogen in the transdermal patch compared with 35-μg oral contraceptives. This statement led to concerns of serious adverse events. Women who have no contraindications for contraception continue to struggle with adherence to daily, weekly, and even monthly regimens. Patients must take responsibility for taking their contraception as scheduled or risk becoming pregnant. The relationship of weight and efficacy of combined hormonal contraception is a concern that many health care practitioners have, and unfortunately, the data available do not answer the question at this time. The most important aspect of prescribing contraception is communication with the patient. Taking complete histories and prescribing contraceptive methods on an individualized basis will offer the patient the optimal method available to the patient.

Use of oral contraceptives, intrauterine devices and tubal sterilization and cancer risk in a large prospective study, from 1996 to 2006

The association of contraceptive methods, including oral contraceptives (OC), intrauterine devices (IUD) and tubal sterilization (TS), with overall and site-specific cancer were prospectively investigated in a cohort of 66,661 Chinese women in Shanghai, 76.7% of whom used contraception. During a median follow-up time of 7.5 years, 2,250 women were diagnosed with cancer. Ever-use of any contraceptive method was not associated with overall cancer risk [adjusted hazard ratio (HR(adj)) = 1.02, 95% CI, 0.92-1.12]. Use of any contraceptive method was associated with increased risk of rectal cancer (HR(adj) = 1.68, 95% CI, 1.08-2.62) and reduced risk of thyroid cancer (HR(adj) = 0.63, 95% CI, 0.38-1.04). Risk of gallbladder cancer increased with ever use of OC (HR(adj) = 2.38, 95% CI, 1.26-4.49). IUD use was associated with a possible reduced risk of thyroid cancer (HR(adj) = 0.64, 95% CI, 0.38-1.07). Longer duration of IUD use decreased risk for breast, thyroid and lung cancers. Ever having a TS was associated with increased uterine body cancer (HR(adj) = 2.50, 95% CI, 1.47-4.25) and decreased risk of stomach cancer (HR(adj) = 0.59, 95% CI, 0.39-0.91). We did not find any contraceptive method to be related to the risk of ovarian cancer but the analyses were based on few events. Although chance findings are a likely explanation for some of the associations found in our study, these findings suggest that various contraceptive methods or reproductive patterns may play a role in the etiology of cancer.

Anchoring junctions as drug targets: role in contraceptive development

In multicellular organisms, cell-cell interactions are mediated in part by cell junctions, which underlie tissue architecture. Throughout spermatogenesis, for instance, preleptotene leptotene spermatocytes residing in the basal compartment of the seminiferous epithelium must traverse the blood-testis barrier to enter the adluminal compartment for continued development. At the same time, germ cells must also remain attached to Sertoli cells, and numerous studies have reported extensive restructuring at the Sertoli-Sertoli and Sertoli-germ cell interface during germ cell movement across the seminiferous epithelium. Furthermore, the proteins and signaling cascades that regulate adhesion between testicular cells have been largely delineated. These findings have unveiled a number of potential "druggable" targets that can be used to induce premature release of germ cells from the seminiferous epithelium, resulting in transient infertility. Herein, we discuss a novel approach with the aim of developing a nonhormonal male contraceptive for future human use, one that involves perturbing adhesion between Sertoli and germ cells in the testis.