Coming Home

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.