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Pregnancy Prevention, Cancer Conception?
By: Sara Fernandez
October 1, 2010
In a world where both public sexuality and the role of women are on the rise, an exponential increase in the number of teenage pregnancies would be guaranteed without the prevalent use of oral contraceptives. With a single prescription, many women, teenagers and beyond, have access to a market catering a wide variety of oral contraceptives(OC). In some cases, the effect of oral contraceptives extends beyond the use of simply preventing pregnancy and assumes the role of lessening the annoyances of irregular periods or excessive amounts of acne. However, because oral contraceptives find success in exposing a woman's body to high amounts of hormones during usage, many woman are hesitant to use them. The rift between uninformed usage and total comprehension of how OCs effect the body leads many women to focus on the immediate positives of OC usage while the acknowledgement of potential dangers remains out of sight and mind. The rumored association OCs have with breast cancer has been the subject of many studies in order to truly solve the matter.
The Functioning of Oral Contraceptives:
In order for a woman to become pregnant, she must release an egg to be fertilized. If the oocyte is fertilized, it becomes a zygote that is then implanted on the nutrient-rich inner-lining of the uterus where it will continue to develop as an embryo. Once the zygote begins its development, the hormones estradiol and progesterone prevent the formation and release of additional oocytes by inhibiting the secretion of follicle stimulating hormone and luteinizing hormone (Losos et al., 2008). The role of birth control in pregnancy prevention is to use man-made versions of estradiol and progesterone, which are naturally used by the body to prevent ovulation. The two major types of OC pills that can be found in the pharmacy today include the estrogen and progestin containing pill and the progestin-only pill (http://www.goaskalice.columbia.edu/0663.html). The "minipill," or progestin-only pill, is known to be less effective; however, the rare side-effects of estrogen usage that bother some women are eliminated when using this pill. While taking birth control, pills are supposed to be administered every day at the same time for approximately three weeks or twenty-one days. During the following seven days, a woman using a twenty-eight day pack will continue to take placebo pills that lack any hormones. A woman will get her normal period during this seven day time span.
Oral Contraceptives on the Market:
Currently there are over thirty oral contraceptive brands available for women to purchase. They each use different formulations, and most claim a 99% pregnancy prevention rate. The three main categories of combination birth control pills include monophasic, biphasic, and triphasic (http://women.webmd.com/features/comparing-birth-control-pill-types-combination-minipills-more). Monophasic pills contain the same levels of estrogen and progesterone, biphasic pills have two different levels, and triphasic have three.
Link Between Estrogen and Breast Cancer:
Systemic hormones, like estrogen and progesterone stimulate tissues, such as the breast, and regulate the synthesis and release of growth factors (http://grants.nih.gov/grants/guide/rfa-files/RFA-DK-94-007.html). Growth factors continue to induce mitosis and development in target tissues. A literary review conducted by J. Russo and I.H. Russo (1998) found that the hormone estrogen plays an important part in the development of breast cancer. The review also states that this development of hormone dependent breast cancer is most prevalent during a woman's postmenopausal years. Russo and Russo observed that estrogen usage leads to increased cell growth and cell division which "could result in turn in the accumulation of genetic damage and stimulation of the synthesis of growth factors that act on the mammary epithelial cells." It is also possible that "estrogen may induce cell proliferation through negative feedback by removing the effect of one or several inhibitory factors present" in the body that would normally prevent the development of mutant cells (Russo & Russo, 1998).
Analysis of Studies:
In a study titled Breast Cancer Among Young U.S. Women in Relation to Oral Contraceptive Use (White et al., 1994), researchers conducted a case-control study on a cohort of women aged 21 to 45. This study sought to determine the association of OC use with breast cancer prevalence in a group of women who had had a lifetime availability of contraceptives. The case group consisted of 747 women with diagnosed breast cancer, while the control group was composed of 961 women without cancer. The study sought to determine the case group's risk factor exposure in comparison to that of the control's. The experiment concluded that "long-term OC use among young women or use beginning near menarche may be associated with a small excess breast cancer risk, possibly due to the susceptibility to genetic damage in breast epithelial cells at ages of high breast cell proliferative activity"(White et al., 1994). The increased odds risk for long term usage (more than ten years) was found to be 1.3. Those who had used OCs for only a short period of time (less than one year) were found to have an odds ratio of 1.0. This odds ratio closely coincides to that of those individuals who had never used OCs.
One of the more recent and larger studies observing the correlation between long-time oral contraceptive use and breast cancer was conducted with a cohort consisting of 116,608 25 to 42 year-old female nurses (Hunter, 2010). This study began in 1989 and concluded in 2001. These women were surveyed in order to categorize them as OC never, past, or current users. Those who were currently using oral contraceptives, and those who had in the past, were asked to note the brand of OC currently being used or used in the past. Follow-up surveys were conducted every two years in order to assess the individuals and the emergence of breast cancer among them. After surveying, 1,344 cases of breast cancer were noted, and it was determined that "current use of any oral contraceptive was related to a marginally significant higher risk"(Hunter, 2010). From a 1.12 relative risk associated with past usage, current usage creates a 1.33 relative risk. Current, long-term OC users, those who had been using for eight years or more, had an increased relative risk at 1.42. Breast cancer was more frequently found in individuals using oral contraceptives with the ingredients triphasic ethinyl estradiol and levonorgestrel together. Relative risk rose to 3.05. Though risks for cancer were found to be higher in those currently using OCs and those having used OCs within the past ten years, these risks returned to an individual user's baseline after approximately ten years of non-usage. The discussion of this study acknowledges the fact that low incidences (less than 2%) of breast cancer cases in their final data "emphasizes that current oral contraceptive use is not a major cause of breast cancer"(Hunter, 2010).
Because breast cancer is a common cause of death for women, it is a prevalent foe to our society. In fact, an article titled Breast Cancer Risk: Perception versus Reality (Westoff, 1999) indicates that when surveyed, "women's perceptions of their risk of developing and dying of breast cancer exceeded the actual risk." The supposed correlation between oral contraceptives and breast cancer only adds to societal paranoia. However, after a period of ten years or more, it was found that the minimal, additional risk caused by hormonal contraceptive use returned to normal for an individual. Though the evidence from these studies indicates that there is a slight increase, if any, for an elevated rate of developing breast cancer during oral contraceptive use, further research should be done on this topic. Major drawbacks to this type of society-wide epidemiological research include the fact that it is difficult to follow such a large cohort of women before and after OC usage. For most researchers, a study with a time span of twenty to thirty years is one that would require adequate funding that may be lacking. And if long term effects cannot be noted in this way, it is difficult to have conclusive results about long-term OC effects on women. Similarly, these studies are out of date in relation to current birth control formulas on the market today. With the most current research available, it can be decided that the probability of developing breast cancer is only minimally increased during and after recent OC usage. In this case, the benefits of a contraceptive pill offer more in preventing unwanted pregnancy than increasing the risk of breast cancer.
Russo, I., Russo J. (1998) Role of Hormones in Mammary Cancer Initiation and Progression. Journal of Mammary Gland Biology and Neoplasia , 3 (1), 49-61.
Losos, J., Mason, K., & Singer, S. (2008). Biology (eighth ed.). New York: McGraw Hill.
Westhoff, C. (1999). Breast Cancer Risk:Perception Versus Reality. 25S-28S.
White, E., Malone, K., Weiss, N., & J, D. (1994). Breast Cancer Among young U.S. Women in Relation to Oral Contraceptive Use. Journal of the National Cancer Institute , 86 (7), 505-14.
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