The pill and breast cancer

What are oral contraceptives and how do they work?

Oral contraceptives are pills containing hormones which are taken in order to prevent pregnancy occurring. They prevent pregnancy by preventing the sperm from reaching the egg and so prevent fertilisation of the egg. They do this in three ways:

It delays or prevents the release of the egg from the ovary. This process is known as ovulation
It creates a physical barrier to prevent the sperm from reaching the eg by causing the mucus around the neck of the cervix to thicken and so making it more difficult for the sperm to pass-through
It makes the lining of the uterus thinner; if a fertilised egg then tries to become implanted, the lining is not suitable and so the implantation fails

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What is the connection between the pill and cancer?

Studies have provided consistent evidence that the risk of both breast cancer and cervical cancer is increased in women who use the combined pill, however, the risks of endometrial, ovarian and colorectal cancers are reduced.

The link between breast cancer and the hormones oestrogen and progesterone which are found in the combined pill is not clear, however, it is known that these hormones can cause a growth increase in some breast cancers which may explain why taking the pill increases the risk of breast cancer.

What are the risks?

There are factors which may add to the risk of developing breast cancer whilst taking the pill. These factors include the following:

The woman's age
Whether the woman is a smoker
Whether the woman is a heavy drinker
Her general health
Being overweight
Her own personal risk of breast cancer such as family history

Can the pill reduce the risk of other types of cancer

As mentioned earlier, it has been noted that taking the contraceptive pill may actually reduce the risk of colorectal cancer, endometrial cancer, and ovarian cancer:

Endometrial cancer - it has been shown that the pill can reduce your risk of endometrial cancer and the longer that you take the pill the lower your risk becomes. In addition, the risk reduction remains for at least 10 years after you stop taking the pill.

It has also been suggested that the use of an intrauterine device (IUD) can also help reduce the risk of endometrial cancer

Ovarian cancer - again, the combined oestrogen/progesterone pill can lower the risk of ovarian cancer and the benefit begins three to six months after starting the pill. Again, the longer you take it the lower your risk becomes. Using the contraceptive injection Depo-Provera has been shown to have the same effect
Colon cancer - it appears that the reduction in risk of cancer is not restricted to cancers of the reproductive system; it has been shown that use of the pill may reduce the risk of developing colorectal cancer although more studies are required before this is proven beyond all doubt.

Naturally occurring oestrogen and progesterone can stimulate the growth and development of some cancers and so it is likely that their synthetic equivalent found in the pill could act in the same way; this would explain the increased risk of breast and cervical cancer from taking the pill

Researchers have now proposed a few reasons why the same hormones may actually reduce the risk of some cancers. These include the following:

They cause the suppression of endometrial cell overproduction as in endometrial cancer
The reduction of the number of ovulation cycles in a woman’s lifetime will reduce that woman's exposure to naturally occurring female hormones and so reduce the risk of ovarian cancer
Lower levels of bile acids in women taking oestrogen orally may reduce the risk of colorectal cancer

Other forms of hormonal contraception and the risks

There are a variety of hormonal birth control medications available. They include the following:

Combination of Birth Control Pills - orally taken medication. The pills contain oestrogen and progesterone
The vaginal ring - it is a small plastic ring which is placed in the vagina. It releases a continuous dose of oestrogen and progesterone
The contraceptive implant or Nexplanon. This contains progesterone and is implanted under the skin. It does not need to be replaced for three years
The contraceptive injection or Depo Provera - this releases progesterone into the body
The hormonal IUD (Mirena or Skyla IUD) - this releases progesterone into the system
The Mini-Pill - also known as the progesterone-only pill

It is believed that the risks of developing breast cancer that is associated with the combined pill may also be associated with other hormonal contraception

Conclusion

Whilst it is considered that the pill has some associated risk of increasing the chance of developing cancer, they are not the same risks as may have existed with the older types of pills which contained higher levels of hormones. Newer pills have much lower levels of hormone and represent a small increased risk of developing breast cancer.

This needs to be taken in context. Safe, effective birth control is vital to many women; not only does the pill prevent unwanted pregnancy, but it is also a useful treatment for acne, premenstrual syndrome, heavy periods and mood swings alongside reducing the risk of some cancers.

It is up to each individual to make an informed decision and balance the risk according to their age, lifestyle, family history and general health