WETZSTEIN: Birth history raises cancer risk

In 1987, I was deeply grateful to welcome my first child into the world.

I have no regrets there.

However, the fact that her arrival occurred when I was 33 years and 6 months old seems to have affected my personal journey.

I have recently been diagnosed with breast cancer.

In reviewing the list of known risk factors, I saw that three were clearly out of my control — I am a woman, white and over 55.

But the only other risk factor that fit me was that my first child was born after age 30.

Why should age at first birth be a risk factor for cancer? And what is the larger meaning of this risk factor in a culture that fully endorses delayed marriage and delayed childbearing?

First of all, the number 30 “isn’t magical. It’s not like on your 30th birthday, all of a sudden, things change” and breast cancer risk shoots up, said Susan Gapstur, vice president for epidemiology at the American Cancer Society and a researcher on behavioral and environmental risk factors for breast cancer.

It’s just that when researchers look at all women and their ages at first childbirth, “it’s in that area of around age 30” that the cancer risk emerges, she explained.

Second, late childbearing is a relatively low risk factor for breast cancer, added Ms. Gapstur, who has a doctorate in epidemiology. Major risk factors include having close female relatives (mother, sister) with breast cancer diagnoses early in life, having mutations on certain genes (known as BRCA1 or BRCA2), and having high doses of radiation to the chest during childhood, she said.

Still, there is a clear correlation between breast cancer risk and not having a full-term pregnancy before 30.

The reason for this is complex, but here’s the gist: When a woman nears the end of her pregnancy, the hormonal changes cause her breast tissues and cells to “fully mature.”

Mature breast tissue is more resistant to abnormal cell changes (i.e., cancer) than immature breast tissue.

So having a baby is protective — and “[i]n particular, having more than one child at a younger age decreases a woman’s chances of developing breast cancer during her lifetime,” says the National Cancer Institute.

We can stipulate that no one knows for sure why anyone gets breast cancer, and many women who get cancer don’t have any risk factors (other than being a woman).

Story Continues →

© Copyright 2013 The Washington Times, LLC. Click here for reprint permission.