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Cancer Genetics

Hereditary Breast Cancer Factors

07/16/2001

Question:

I have a few questions regarding hereditary breast cancer. Besides the breast cancer genes, do other factors affect whether the breast cancer in a family is hereditary? I was wondering if the type of tumor and/or hormone receptors give any indication to whether breast cancers are hereditary?

I understand only approx. 10 % of breast cancers are hereditary.

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

We are researching to see what type of tumor my mother had and whether her receptors were positive or negative.I had a medullary tumor with 2 intra-mammary nodes positive and 14 axillary nodes negative. My tumor was both estrogen and progesterone negative.

It has been suggested to my sister, age 38, to consider genetic testing and tamoxifen preventive treatment. 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 hereditary 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 where I can find more information on this subject.

Answer:

I need to reverse your question. You asked for `any information as to whether any other factors help to determine the hereditary factor.` The hereditary factor is only determined by your genes. Other factors may interact with your genes (environment, viruses, cigarette smoking). The question I will answer is, `In breast cancer caused by a hereditary susceptibility, what kind of characteristics do the tumors have?`

Women who develop breast cancer due to an inherited susceptibility, particularly due to a change in the BRCA1 or BRCA2 genes, can have tumors with a variety of characteristics. While tumors caused by a change in the BRCA1 gene are most likely to be estrogen/progesterone receptor negative, they can still be receptor positive. Tumors caused by a change in the BRCA2 gene are about 50% receptor positive and 50% receptor negative.

Women with changes in the BRCA1 or BRCA2 genes can have any type of breast cancer although invasive ductal carcinoma is the most common -- because it is the most common in general.

Women with inherited susceptibilities are also more likely to develop cancer at an earlier age although they can develop cancer at any age. They are also more likely to develop other types of cancer, particularly ovarian cancer in the case of BRCA1 and BRCA2.

Tamoxifen will not prevent cancer recurrence in a person who has had receptor negative breast cancer. Since many cancers are receptor positive, even in women with an inherited susceptibility, tamoxifen may still be appropriate to help prevent breast cancer in a woman who has not had cancer herself.

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Response by:

Judith A Westman, MD Judith A Westman, MD
Associate Professor, Clinical Internal Medicine, Pediatrics and Medical Biochemistry
College of Medicine
The Ohio State University