Researchers Develop New Classification for Breast Cancer

Dorian Martin Health Guide
  • Menopause can bring many things. One of them can be breast cancer. For instance, the American Cancer Society reports that women who experienced more menstrual cycles because they started menstruating early (before age 12) and/or went through menopause later (after age 55) face a slightly elevated risk of breast cancer, possibly due to a longer lifetime exposure to the hormones estrogen and progesterone. In addition, aging is another risk factor for breast cancer. In fact, two out of three invasive breast cancers are found in women who are 55 and older.

    And the numbers of people who are stricken with breast cancer are daunting. The World Health Organization reports that there are approximately 1.3 million new cases of breast cancer annually. Furthermore, 450,000 die from this disease each year. Additionally, some places in the world are seeing increases in the number of cases diagnosed. For instance, the BBC reported in 2011 that breast cancer rates for British women who are in their 40s and 50s had increased by 50 percent between 1979 and 2009.

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    But equally important is new research that underscores that breast cancer does not fall into one succinct category. In a newly released study, researchers used six different technologies to identify defects in DNA, RNA and proteins in 348 tumors from women who had breast cancer. The scientists ended up identifying four standard molecular subtypes of breast cancer.  

    This finding marks a change from the three groups of breast cancer that doctors previously have used. According to a story in the Houston Chronicle, this previous group consisted of:

    • Hormone receptor-positive disease, which were treated with hormone-targeted therapy.
    • HER2-positive. The National Institutes of Health reported that breast cancer tumors that have the HER2 receptor fall into this category.
    • Triple-negative disease, which lacks the receptors for estrogen and progesterone and the HER2 genes.  

    The National Institutes of Health reports that the new subtypes are:

    • Basal-like. The TCGA Research Network identified significant genomic similarities between this subtype of breast cancer, which is one of the most deadly subtypes of cancer, and serious ovarian cancer.  The researchers’ analysis suggest that both of these types of cancer could be successfully treated by agents that inhibit blood vessel growth, thus cutting off the supply of blood that feeds the tumor, and compounds that target DNA repair. The Houston Chronicle reported that this study suggests that women who have this subtype could benefit from doses of the less toxic drugs used to treat ovarian cancer rather than with anthracyclins, which are presently used but provide harsh side effects.
    • HER2-enriched (HER2E.) Using the genomic findings of HER2-positive tumors, researchers determined that half of the samples could be characterized as the HER2E subtype. The other half make up the Luminal subtypes, which are described below.
    • Luminal A (LumA), which forms in the luminal cells that line milk ducts. The Luminal A subtype had a good prognosis, suggesting that women with these types of tumors might benefit from hormonal therapy to block estrogen from feeding the cancer.
    • Luminal B (LumB), which also forms in the luminal cells. This subtype did not have a good prognoses so researchers believe that women with this subtype may benefit from chemotherapy and hormonal therapy.

    The Luminal subtypes had the lowest overall mutation rate, but also had the largest number of genes that were significantly mutated. The researchers believe that each of the genes that have significantly mutated in these two subtypes is speeding the cancer progression.

  • So what are these subcategories important? Researchers believe that they can now identify which treatments work best for patients based on the tumor’s genetic profile, thus creating a personalized approach to fighting breast cancer. And that potentially may be very good news for the successful treatment of women who are diagnosed with this disease!

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    Primary Sources for This Sharepost:

    American Cancer Society. (2012). Breast cancer.


    Colliver, V. (2012). Breast cancer gets redefined. Houston Chronicle.

    National Institutes of Health. (2012). Study reveals genomic similarities between breast cancer and ovarian cancer.

    Preidt, R. (2012). Gene study yields new clues to breast cancer. MedlinePlus.

Published On: September 24, 2012