Birth Control in Teens – Why Not? The Breast Cancer Link

By Dr. Susan Caldwell

In the last post, we explored how the hormones in birth control interfere with the normal process of maturation of the reproductive system in a teen girl. Doctors may have good intentions when they prescribe these medications, but most do not realize the potential harmful effects that may develop as a result of taking this medication, such as significantly increasing the risk of breast cancer later in life. For this and many other reasons, we must be cautious when considering prescribing birth control to teens.

There is no disputing the fact that the hormones found in the birth control pill are classified as carcinogens. Not just mild carcinogens but the most dangerous type – Group 1 carcinogens[1]. This is the same category where you would find nicotine and asbestos. The hormones in birth control increase the risk of breast, cervical, and liver cancers. The link between hormonal contraceptives and breast cancer is significant. I was skeptical when I first heard this until I studied the mechanisms by which this can occur.

Breast cancer is an epidemic in the United States. One in every 8 women are diagnosed with breast cancer. The incidence of breast cancer has significantly increased in the last 50 years since the birth control pill was introduced. Although there are many factors that have likely contributed to this increased incidence, we must consider birth control as to be a major contributor given its effect on breast tissue. Many newly diagnosed breast cancer patients have told me on the first visit after their diagnosis, quite defensively, that they could no longer take any hormonal contraceptives due to the breast cancer diagnosis. They frequently lamented that they took birth control pills in the first place.

Whether a woman’s breast cancer risk is increased by hormonal birth control or not depends on when in her life she is exposed to the hormones in birth control.

Let’s look at the natural process of breast maturation. Prior to a woman’s first full-term pregnancy, her breast tissue remains in a very immature, fragile stage of development. At this stage, her breast tissue is much more susceptible to the carcinogenic effects of birth control. For example, the estrogen-like component in hormonal birth control (ethinyl estradiol) mimics natural estradiol but is not the same hormone; therefore, its effects on the breast, and other organs, are different, and in many cases, toxic. All hormones are not created equal, remember.

credit: Breast Cancer Prevention Institute

Breast tissue becomes fully mature during pregnancy/breastfeeding, and only then becomes much less vulnerable to carcinogens compared to the breasts of adolescent girls. Breast tissue is made of lobules, where milk is made, and ducts, the passageways through which milk flows to the nipple. Consider the analogy of an oak tree. When an oak tree is young, its leaves and branches are tiny and vulnerable to damage from storms. However, when that tree is decades older, it is much more likely to withstand the weather. Breasts are similar in that over time, maturation occurs so that breast tissue is much more resilient and less likely to be harmed by carcinogens. For a woman, this maturation occurs when she becomes a mother during pregnancy due to the continued high levels of estradiol, progesterone, and hCG (human chorionic gonadotropin) hormones. The further the woman’s first pregnancy continues, the more mature (cancer resistant) the breast tissue becomes.

Interestingly, if a pregnancy is terminated (by abortion or pre-term delivery) before the breast tissue has become significantly mature (at about 32 weeks gestation), her risk of developing breast cancer increases. If a pregnancy is interrupted by abortion or pre-term delivery, the natural process of tissue maturation is suspended and the developing cells are then more vulnerable to carcinogens. [2]

You may have heard that women who have never been pregnant are at higher risk of breast cancer. This makes since if you understand the process of breast tissue maturation. These women have breast tissue that has remained in an immature state that is more susceptible to carcinogens.