In part one of this series, I discussed the growing incidence of breast cancer around the world, among other issues. In this section, I will shed light on how our genes influence this disease.

As with many other diseases, the prognosis of a woman with breast cancer may be heavily influenced by her genetic make-up. For instance, in the United States of America, most women who develop breast cancer are of European ancestry. Most of these ladies have a type of breast cancer that is partially stimulated by exposure to estrogen. After decades of monthly hormonal cycles during menstrual cycles, this disease typically hits.

Estrogen-sensitive breast cancers may be manipulated, so to speak, by treatment with drugs which block estrogen receptors on cancerous cells. Herceptin and tamoxifen are two popular drugs used for this purpose. Look at it this way, these cancerous cells thrive off estrogen. Since these drugs block the passage of estrogen into malignant breast cancer cells, they essentially help “starve” the cancerous tissue.

On the other side of the coin, Asian women, as well as black women in the U.S.A.and Africa are more likely to develop the type of breast cancer that does not respond to estrogen blockade. This type of cancer, know as estrogen-receptor negative or ER-negative breast cancer can be particularly aggressive. To make matters worse, ER-negative breast cancer strikes women an average of 10 years earlier than ER-positive breast cancer, making a bad situation even worse.

If that were not enough bad news, medical research has shown that approximately 40% of African-American breast cancer patients who develop their disease before the menopause have a particularly aggressive form of ER-negative breast cancer. This type of cancer is called the basal-like subtype, and is resistant not only to estrogen, but also to progesterone, the other female hormone that can be targeted in breast cancer treatment.

Asian ladies have their own battle to fight. While fewer than 10% of Americans with breast cancer have the form caused by an inherited genetic mutation, such is not the case with Asian women which have a higher likelihood of inheriting these potentially lethal genes. Those who inherit these mutated genes, namely, BRCA1 and BRCA2, have up to a sevenfold increased risk of developing breast cancer. In addition these women are more likely to develop their case of breast cancer prior to age 50 and are also more likely to develop recurrence of cancer in their other breast.

Asian women have to contend with yet another obstacle. They tend to have denser breast tissue than others, making mammograms more difficult to interpret. Furthermore, studies have shown that dense breast tissue is more likely to sprout cancer.

There's still more to learn, so stay tuned for the next article.