Tuesday, October 2, 2007

Risk Factors for Breast Cancer

Updated 3/2017-- photos and all links (except to my own posts) removed as many no longer active.

October is breast cancer awareness month. It's a good time to review the risk factors for breast cancer. A risk factor is anything that affects your chance of getting a disease, such as cancer. But having a risk factor, or even several, does not mean that you will get the disease. Most women who have one or more breast cancer risk factors never develop the disease, while many women with breast cancer have no apparent risk factors (other than being a woman and growing older). Even when a woman with breast cancer has a risk factor, there is no way to prove that it actually caused her cancer. The National Cancer Institute has an interactive Breast Cancer Risk Assessment Tool that can be used to measure risk of invasive breast cancer.
Risk Factors that can not be changed
  • Gender--Just being a woman puts you at risk of having breast cancer. Yes, men can develop breast cancer, but this disease is 100 X's more likely to develop in a woman.
  • Age--Your risk goes up as you get older. [I'm with George Burns--"don't like the alternative"] Close to 80 percent of breast cancers occur in women older than age 50. In your 30s, you have a one in 233 chance of developing breast cancer. By age 85, your chance is one in eight.
  • Genetic Risk Factors--Between 5 percent and 10 percent of breast cancers are inherited. Defects in one of several genes, especially BRCA1 or BRCA2, put you at greater risk of developing breast, ovarian and colon cancers. Usually these genes help prevent cancer by making proteins that keep cells from growing abnormally. But if they have a mutation, the genes aren't as effective at protecting you from cancer.
  • Race--While white women are slightly more likely to develop breast cancer than are African-American women, the African-American women are more likely to die of this cancer. Asian, Hispanic, and Native-American women have a lower risk of developing and dying from breast cancer.
  • Personal History of Breast Cancer--A woman with cancer in one breast has a 3- to 4-fold increased risk of developing a new cancer in the other breast or in another part of the same breast. This is different from a recurrence (return) of the first cancer.
  • Family History of Breast Cancer--If you have one first-degree relative — a mother, sister or daughter — who was diagnosed with the disease before age 50, your risk is doubled. If you have two or more relatives, your risk increases even more. Just because you have a family history of breast cancer doesn't mean it's hereditary, though.
  • Abnormal Breast Biopsy Results--The proliferative lesions without atypia (those with excessive growth of cells in the ducts or lobules of the breast tissue) seem to raise a woman's risk of breast cancer slightly (1½ to 2 times normal). The proliferative lesions with atypia (those with excessive growth of cells in the ducts or lobules of the breast tissue, and in which the cells no longer appear normal) have a stronger effect on breast cancer risk, raising it 4 to 5 times higher than normal.
  • Menstrual Periods--Women who started menstruating at an early age (before age 12) or who went through menopause at a late age (after age 55) have a slightly higher risk of breast cancer.
  • Previous Chest Radiation--Women who, as children or young adults, had radiation therapy to the chest area as treatment for another cancer (such as Hodgkin disease or non-Hodgkin lymphoma) are at significantly increased risk for breast cancer. This varies with the age of the patient at the time of radiation.
  • Diethylstilbestrol (DES) Exposure--For more information on DES see the separate American Cancer Society document, DES Exposure: Questions and Answers. (Table credit)

Risk Factors Related to Life Style (ones that can often be changed)
  • Oral Contraceptive Use --While women are taking oral contraceptives and for 10 years after stopping these agents, there is a small increase in the relative risk of developing breast cancer. There is no significantly increased risk of having breast cancer diagnosed 10 or more years following cessation of the oral contraceptive agent.
  • Postmenopausal Hormone Therapy (PHT)--Among current users of HRT and those who have ceased use 1-4 years previously the relative risk of having breast cancer diagnosed increases by a factor of 1.023 for each year of use. The risk of breast cancer appears higher with combined oestrogen and progestogen combinations. Mammograms of patient before and after three years of hormone replacement therapy showing increase in density caused by treatment 
  • Not Having Children, or Having Them Later in Life--Women who have had no children or who had their first child after age 30 have a slightly higher breast cancer risk. Having multiple pregnancies and becoming pregnant at an early age reduces breast cancer risk.
  • Breast-feeding--Some studies suggest that breast-feeding may slightly lower breast cancer risk, especially if breast-feeding is continued for 1.5 to 2 years. But this has been a difficult area to study, especially in countries such as the United States, where long-term breast-feeding is uncommon.
  • Physical Activity--Evidence is growing that physical activity in the form of exercise reduces breast cancer risk. The question is how much exercise is needed. In one study from the Women's Health Initiative (WHI) as little as 1.25 to 2.5 hours per week of brisk walking reduced a woman's risk by 18%. So lace up.
  • Alcohol--A recent study showed the following: Compared to women who consumed less than one drink per day, risk of breast cancer was increased by 10% among women who consumed one to two drinks per day, and by 30% among women who consumed three or more drinks per day. Each type of alcohol (beer, wine, or spirits) appeared to have a similar effect on breast cancer risk. The link between alcohol and breast cancer did not appear to vary by age or ethnicity.
The Susan G Komen Foundation has a very nice interactive program (audiovisual) that will enable you to better understand the development of breast cancer, the risk factors of breast cancer, diagnosis and prognostic factors and treatment options. Anatomy of Breast Cancer - Updated

  • All Types of Alcohol Increase Breast Cancer Risk--CancerConsultants.com
  • Abortion and Breast Cancer--Once Again, There is no Link--TBTAM
  • National Cancer Institute-- Breast Cancer Information Page
  • Clinical Review--ABC of Breast Diseases--Breast Cancer--Epidemiology, Risk Factors, and Genetics; BMJ 2000;321(7261):624 (9 September); K McPherson, C M Steel, J M Dixon
  • Rating the Risk Factors for Breast Cancer; Ann Surg. 2003 April; 237(4): 474–482; S. Eva Singletary, MD, FACS
  • What Are the Risk Factors for Breast Cancer?--American Cancer Society article
  • Breast Cancer--MayoClinic.com article
  • breast cancer risk factors-- Susan G. Komen Breast Cancer Foundation


Jeffrey Parks MD FACS said...

Well done!

Randi said...

You listed family history of breast cancer as a major part of breast cancer risk. Now, there's a way that those with that history can make a difference in breast cancer research.

Women play many important roles throughout their lives—daughter, mother, and friend—but no relationship is as unique as the one between two sisters. Sister Study researchers hope the sisters of women with breast cancer can play another important role by helping discover how our environment and genes affect our chances of developing breast cancer.

The Sister Study is a nationwide effort, conducted by the National Institute of Environmental Health Sciences, to learn about environmental and genetic causes of breast cancer. Women ages 35 to 74 are eligible to join if their sister (living or deceased), related to them by blood, had breast cancer; they have never had breast cancer themselves; and they live in the United States or Puerto Rico.

The Sister Study is particularly committed to enrolling women in every state, and from all backgrounds, occupations, races and ethnicities, so the study results represent and benefit all women. The women enrolled in the Sister Study look like many of our relatives, friends, and co-workers. They may even look like you.

Of the more than 41,000 women currently enrolled, here are a few who are making a difference in breast cancer research. Retiree Cruz Mireles, 58, joined because her sister is a breast cancer survivor. Jean Peelen, 65, a government retiree and senior model enrolled and helps spread the word about the Sister Study because one sister is a breast cancer survivor and another died as a result of the disease. Also, Donna Castleberry, 46, who works in a busy Los Angeles advertising firm, and Barbara Moore, 57, an on-the-go Labor Relations Specialist for AFSCME did it because their sisters died of breast cancer, before they even reached the age of 50.

The study needs to enroll 50,000 women by spring 2008, and with your help, it can.

“Many women have heard about the Sister Study, but they haven't signed up yet, and we really need them now,” said Dale Sandler, Ph.D., Chief of the Epidemiology Branch at NIEHS and Principal Investigator of the Sister Study. “Doctors know very little about how the environment may affect breast cancer, that is why the Sister Study is so important. We hope women will make that call today,” she added.

Organizations in partnership with the Sister Study include the American Cancer Society, the Intercultural Cancer Council, the National Center on Minority Health and Health Disparities of the National Institutes of Health, Sisters Network Inc., Susan G. Komen for the Cure, and Y-ME National Breast Cancer Organization.

The Sister Study is available in English and Spanish and can be done from home when it is convenient for women. To learn more about the Sister Study, visit the web site www.sisterstudy.org, or for Spanish www.estudiodehermanas.org. A toll free number is also available 1-877-4SISTER (877-474-7837). Deaf/Hard of Hearing call 1-866-TTY-4SIS (866-889-4747).

Woman by woman….Sister by sister…We can make a difference.

Karen Little said...

A lecturer at university (I can't now remember what his specialty was, but Ithink he was a surgeon) once told us that women who have a university degree are more likely to get breast cancer, as well as women who work night shift (something to do with us missing our 2am melatonin surge which can only occur in complete darkness). I don't know what his references were, but I'm not sure if I believe him.

This was a really interesting post - thanks

rlbates said...

I've never seen the "melatonin surge" listed as a reference. I have seen the education thing listed, but it usually refers back to the delay in having babies.

denverdoc said...

Melatonin is protective against breast cancer--Alzheimer's too! Statistics show a much lower incidence of breast cancer in blind women.

Lest women freak out at your before and after pictures of breast density after use of HRT is initiated--this is much less likely to occur if micronized progesterone is used in therapy rather than medroxyprogesterone aka Provera. And it does not necessarily happen to this degree to every woman who chooses HRT after menopause.