Causes Of Breast Cancer

From WebHealth

[edit] Causes Of Breast Cancer

We do not know what causes breast cancer, but we know about several breast cancer risk factors. For instance, it is known that the length of ovarian estrogen activity between the first period (menarche) and the last period (menopause) of a woman is directly related to breast cancer risk. The incidence curve of breast cancer is highest just prior to menopause and flattens out after. Another observation, which supports this, is the fact that removal of both ovaries (oophorectomy) at a younger age reduces the risk for breast cancer later in life.

The birth control pill (=oral contraceptives or BCP), which was originally feared to possibly produce breast cancer, does not pose an increased risk during the reproductive years as the ovarian function gets suppressed by it making the BCP breast cancer risk neutral or even 20% less frequent.

However, in the menopause postmenopausal estrogen replacement carries with it an estrogen side effect consisting of a 1.5 to 2-fold accumulative risk for breast cancer over a 10 to 20 year time span. In the past it was thought that a reduced rate of osteoporosis and reduction in heart attacks would increase life expectancy overall with hormone replacement therapy following menopause. However, this has been proven wrong in large trials that came out in 2004 and now the issue of hormone replacement therapy is in flux. Currently the thinking is that one has to individualize therapy, use good nutrition and exercise to prevent osteoporosis and in the case of control of hot flashes use the lowest possible estrogen hormone replacement for less than a total of 5 years. However, discuss this with your family doctor and/or gynecologist.

There is a peculiar linear relationship between total fat intake per day and the death rate from breast cancer. Epidemiological studies show that the daily fat intake in the Netherlands is about 160 grams/day. In El Salvador it is only 40 grams/day.

The adjusted death rate from breast cancer in the Netherlands is 25-fold higher than in El Salvador. Although we do not have all the answers why breast cancer deaths (and by the way many other cancer rates as well) are lower with less fat intake, it is self explanatory that a diet with less than 40 grams of fat per day is highly recommendable to prevent breast cancer and also heart attacks.

There are also genetic risks for some families with a higher breast cancer incidence. In such families the risk is 1.5 to 3 times higher than for the average population. This is due to an inherited mutation in a BRCA1 or BRCA2 breast cancer­susceptibility gene, which can now be determined with special blood tests. As the lifetime incidence of breast cancer in mutation carriers is above 50 percent, these women have to be screened much more vigorously as the rest of the female population. These women come from families where close female relatives had early onset breast cancers (at an age of the late twenties/early to mid thirties).

Home page

Cancer overview

More breast cancer

References:

The following references were used apart from my own clinical experience:

1. Cancer: Principles &Practice of Oncology, 4^th edition, by V.T. De Vita,Jr., et. al J.B. Lippincott Co.,Philadelphia, 1993. Vol.2: Chapter 48.

2. The Merck Manual, 7^th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 177.

3. Cancer: Principles&Practice of Oncology. 5th edition, volume 1. Edited by Vincent T. DeVita, Jr. et al. Lippincott-Raven Publ., Philadelphia,PA, 1997. Chapter 36: 1541-1616.

4. BS Herbert et al. Breast Cancer Res 2001;3(3):146-149.

5. BS Herbert et al. J Natl Cancer Inst 2001 Jan 3;93(1):39-45.

6. Conn's Current Therapy 2004, 56th ed., Copyright © 2004 Elsevier

7. Ferri: Ferri's Clinical Advisor: Instant Diagnosis and Treatment, 2004 ed., Copyright © 2004 Mosby, Inc