So far, we have discussed the physiology of the breast and how it becomes prone to breast cancer (BC) under the influence of estrogen, a WHO Group 1 carcinogen. We have seen that the hormone placental lactogen, secreted in the third trimester, helps to mature 85% of the immature, cancer-prone cells of the breast into cancer-resistant cells. With each successive pregnancy, more of the remaining 15% of cancer-prone cells become cancer resistant. See here to catch up on the details.
I’ve written a brief glossary of the terms used in these studies here. If you see a term with which you are unfamiliar, you’ll find it in the glossary.
Today we look at an important paper in the breast cancer literature. This paper reports on the single greatest reproductive risk factor in the development of breast cancer: age at first birth. As we shall discuss after the summation of the paper, the results tie in very well with our model of breast physiology and the effects of induced abortion.
Title: AGE AT ANY BIRTH AND BREAST CANCER RISK
Authors: Dimitrios Trichopoulos, Chung Cheng Hsieh, Brian MacMahon, Tong-ming Lin, C. Ronald Lowe, Antonio P. Mirra, Bozena Raynhar, Lva J. Salber, Vasilios G. Valaoras, Shu Yuasa.
Journal: International Journal of Cancer, 1983, 31:701-704
{The authors of this international study are from Harvard University, Duke University, Yugoslavia, Wales, Greece, Taiwan, and Japan}
This case control study contained reproductive data from 4,225 women with BC (cases), and 12,307 hospitalized women without BC (controls). It is important to note that abortions prior to 5 months were excluded from the study.
Nulliparous women were used as controls for parous women.
All data are reported with the statistical significance of the 95% confidence interval.
Overall, the average age at first birth in this study was 24.8 years. The authors established an increase of 3.5% per year in the relative risk (RR) of developing breast cancer, for every year that women delay a first full term pregnancy (FFTP) after the age of 24.8 years.
The relative risk (RR) of breast cancer in parous women with multiple pregnancies is reported as follows for increasing ages with single through multiple births:
Age at first birth: 15. In these women, if the woman had one child per year beginning at age 15, then her RR of breast cancer was:
1 child- 0.52
2 children- 0.53
3 children- 0.38
4,5 children- 0.37
That means that this young mother’s lifetime RR is half of that of a nulliparous woman (52%) at one child and drops to almost 1/3 (37%) the risk of a nulliparous woman’s risk if she has 4 or 5 children.
Age at first birth: 18. In this group, if the women have a two-year interval between children, the RR’s are:
1 child- 0.58
2 children- 0.60
3 children- 0.45
4,5 children- 0.43
Age at first birth: 18 (that’s not a typo. It’s 18). Five-year interval between children. RR’s are:
1 child- O.58
2 children- 0.61
3 children- 0.49
4,5 children- 0.46
Age at first birth: 30. Two-year interval between children. RR’s are:
1 child- 0.87
2 children- 0.98
3 children- 0.84
4,5 children 0.83
Age at first birth: 35. One-year interval between children. RR’s are:
1 child- 1.03
2 children- 1.19
3 children- 1.05
4,5 children- 1.06
The numbers for the last category of women actually show slight increases in the risk for breast cancer.
Another curious phenomenon is the slight uptick in RR between a first and second pregnancy in all age categories, followed by a significant drop in RR in 3+ pregnancies. Even so, The RR’s are well below those of nulliparous women.
The results of this study are entirely consistent with what is known of breast physiology. The longer women delay a FFTP, the longer the immature Type 1 and Type 2 cells of the lobules have to become cancerous, and the longer the woman delays the protective effect of placental lactogen, which matures those cancer-prone cells in the last trimester.
These data present the most significant, but hardly the only, risk factor for BC. While the authors did not include women who had abortions, we shall see in many studies to come that there is a consistent RR of BC from induced abortion.
This October, please consider $upporting the following who desperately need our $upport to get the truth out*:
Breast Cancer Prevention Institute
Coalition on Abortion/Breast Cancer
*I have no institutional affiliation or membership with either group. Karen Malec and BCPI have been great resources for me, utterly generous with their time and resources.
18 is very young to have children
how does the effect of breastfeeding enter into this equation?
especially prolonged and ecological breastfeeding.
Although I had my first child at age 30 (I would have married younger but hey, men weren’t interested in women who didn’t want to sleep around)
I had 4 children every 2 years and breastfed until the next baby was born.
My last child I breast fed for 3 years.
Pregnancy and lactation changed my body for the better!
[…] See some-more here: The ABC Literature: #2 « Coming Home […]
[…] discerning reader will recognize Trichopoulos as one of the authors in yesterday’s paper #2. This group is from Harvard University, Greece, and […]
Mary Catherine:
You ask, ” How does the effect of breastfeeding enter into this equation?” The study, Beral et al. 2002, reviewed 47 studies conducted in 32 countries and concluded that if women in developed nations would increase their lifetime duration of breastfeeding and increase the sizes of their families, they would cut breast cancer rates by over one-half. Research shows that the more months a woman spends breastfeeding, the greater the reduction in breast cancer risk. One reason for this is that breastfeeding suspends the menstrual cycles or they have anovulatory cycles, so they are exposed to less estrogen. Experts agree that women, who start menstruating at a late age and go into menopause at an early age, have fewer menstrual cycles and a lower breast cancer risk.
Thank you Karen.
Although I started to have my family a little late (my first baby at 31) I had 3 more children after that spaced about 2.5 years apart and breastfed pretty much for a period of 10 years.
My last child I breastfed for 3 years and when my periods returned they were very different from those I experienced prior to childbearing.
In fact, other than migraines and some mild cramping, it was a breeze and I went into menopause by age 50.
Pregnancy, childbirth and breastfeeding had a great positive impact on my physical health. Although I was sick alot during those years, those illnesses were simply colds and flu from being tired etc.
I have few complaints if any now. I’m much healthier and look about 10 years younger than my peers.
Four children is not alot and I would have loved to have more but circumstances did not permit this.
I have several friends who have 7 or more children and all are in great health and look much younger than their age.
Women have been sold a lie. We have been told that pregnancy and childbearing are enslaving. We have been told that having child kills your career opportunities.
Instead of fighting for better maternal health care, better mat leave and benefits, feminists have two solutions: contraception and abortion.
It’s our duty to see that our daughters don’t buy into that lie.
Thanks for all the great work you do in this area.🙂