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Breast Cancer

Hereditary breast cancer and tamoxifen

07/12/2001

Question:

I have a few questions regarding hereditary breast cancer. I was wondering if the type of tumor and hormone receptors give any indication to whether breast cancers are hereditary. I understand only approx. 10 % of breast cancers are hereditary.

My mother was diagnoased postmenopausal, age 55, had a lumpectomy and radiation treatment and has been cancer free fo 14 years. She has 4 sisters and 3 nieces with no history of breast cancer. I was diagnosed premenopausal, age 39, with mastectomy and 4 cycles of CA chemotherapy treatment and cancer free 5 years.

It has been suggested to my sister, current age 38, by her doctor to consider genetic testing and tamoxifen preventive treatment.

We are looking for the information regarding the type of tumor and hormone receptors my mother had. I had a medullary tumor with 2 intra-mammary nodes positive and 14 axillary nodes negative. My tumor was both estrogen and progesterone negative. I have been told and read that tamoxifen would not benefit me.

If my mother`s tumor was hormone receptor negative also, would there be any benefit for my sister to consider tamoxifen? Also, if my mother`s tumor was a completely different type of breast cancer tumor than mine, does that have any relationship with whether our cancers are hereditary.

I see so much about herediary breast cancer and the number of family members who have it. But I can`t seem to find any information as to whether any other factors help to determine the hereditary factor. I would like any information you can give me or wher I can find more information on this subject.

Thank you.

Answer:

You have submitted a very important question that I will answer in detail for others to read as well. An inherited predisposition to breast cancer is determined by the presence of mutations of certain genes. At this time, the two genes most associated with breast cancer are BRCA1 and BRCA2(breast cancer 1 and 2). These genes, when functioning correctly, help to suppress the growth of cancer cells. When the function becomes altered, called mutation, the risk of developing breast cancer increases. It does not mean that every person with such mutations will develop cancer. Many never will. Tests have been developed that can detect mutations in these genes. Only 5-10% of all breast cancer patients have the inherited BRCA1 or BRCA2 mutation. Most breast cancer cases have no family history of inherited predisposition to breast cancer. The important facts to consider about being tested for BRCA1 and 2 mutations are: The test does not prevent women who carry the mutation from getting breast cancer. It cannot cure existing disease. The test does not deliver conclusive results about a woman`s predisposition to disease. For example, the mutation may be a normal variation or a harmful one. There could be an unidentifed gene predisposing to breast cancer we have not labeled as yet. If a woman tests negative for the gene mutation, it does not protect her from breast cancer as 1 in 8 women without mutations face the lifetime risk of delevoping breast cancer. On the positive side, if test results find the woman does have the mutations, she is in a position to make health management decisions. One risk reduction option is a bilateral prophylactic mastectomy. One study showed a reduction in breast cancer incidence by 90% in women with family history of the disease who had this surgery. Another option is called chemoprevention, taking the drug Tamoxifen. Tamoxifen has been approved by the FDA for reduction of breast cancer in women at a high risk for the disease. This decision was based largely on results of one clinical trial called BCPT(Breast Cancer Prevention Trial). The drug has diverse side effects such as increased risk of endometrial cancer, stroke and deep vein blood clots. The decision to take it is very complex. There are many unanswered question that have not been researched such as: Does it reduce breast cancer risk in BRCA1 and 2 mutations carriers? There have been no studies to answer this question. Other unanswered questions are, does the drug really reduce mortality and extend a woman`s life, or how long can one take the drug? High risk women must carefully weigh thse benefits and limitations. Your sister must have reliable quality information on all of the risks and benefits of chemoprevention drugs before she decides whether to take Tamoxifen.

Women considering genetic testing must receive genetic counseling to receive accurate and unbiased information about the benefits and limitations of taking the test. Women must weigh the benefits of genetic testing against potential discrimination. Women with a strong family history of breast cancer should seek maximum surveillance of mammograms, clinical breast exams, and breast self exams. The question you have about estrogen negative receptors reacting to tamoxifen is accurate. In the BCPT the risk reduction with taking Tamoxifen resulted in estrogen postive breast cancer but not with estrogen negative receptors. Thank you for your question. If any of this information is unclear to you, please do not hestitate to write again for clarification.

For more information:

Go to the Breast Cancer health topic, where you can:

Response by:

University of Cincinnati Janet Trigg, RN, MSN, EdD
Formerly:
College of Nursing
University of Cincinnati
Janet Trigg, RN, MSN, EdD