The Effects of Genetics on Breast Cancer: An Update
In the United States, breast cancer is the most common cancer among women of all races. Unfortunately, it is also the second leading cause of cancer death in this gender population. It is estimated that in 2012, about 227,000 new cases of invasive breast cancer and about 63,000 new cases of non-invasive breast cancer (an early form of breast cancer) will be diagnosed in this country. This will lead to about 39,500 deaths from breast cancer. In their lifetime, about 1 in 8 (12 percent) women in the US will develop invasive breast cancer. This is a very chilling statistic, which makes early screening and detection only that much more important. Breast cancers that are discovered at earlier stages have a much higher change of cure and survival.
Up to 10 percent of breast cancers are thought to be hereditary. These cancers are a result of genetic information passed from a parent to their offspring. Genetic information is passed through chromosomes. During conception, half of a person’s 46chromosomes are obtained from the mother and half from the father. The genetic information in these chromosomes is encoded in DNA. This DNA contains the instructions for building proteins that make up your body and help with all its functions. Unfortunately, if there is an error, or mutation, in this DNA, that mutation will appear in all the cells produced by that particular DNA.
Most inherited cases of breast cancer are associated with two abnormal mutations in the DNA: BReast CAncer gene one and BReast CAncer gene two, abbreviated BRCA1 and BRCA2. Everyone has BRCA1 and BRCA2 genes, because the normal function of the BRCA genes is to repair cell damage and keep breast cells growing normally. This prevents us from developing cancer. But the problem is that when these genes contain abnormalities or mutations, the breast cancer risk increases, since this leads to irregularities with the normal repair mechanism in breast cancer tissue.
Abnormal BRCA1 and BRCA2 genes may account for up to 10 percent of all breast cancers, or 1 out of every 10 cases. Women having these particular abnormal genes can have up to an 80 percent risk of being diagnosed with breast cancer during their lifetimes. Breast cancer in these women is more likely to occur at a younger age, be more aggressive with a higher chance of spreading, and occur in both breasts. Apart from breast cancer, these women are also much more likely to develop cancer of the ovary (2nd most common cancer after breast), pancreas, cervix, uterine, colon, stomach, gall bladder, bile duct, thyroid, and a type of skin cancer called melanoma.
. The BRCA1 and BRCA2 mutations are passed onto children in an autosomal dominant pattern. This means that even if one parent is carrying a mutation on even one of their 46 chromosomes, half of their children will be affected.
The BRCA mutation is detected through a blood test collected at your doctor’s office or a lab. Possible women who qualify for BRCA mutation testing include those with a personal or family history of:
- Breast cancer diagnosed at age 50 or younger
- Ovarian cancer at any age
- Two separate breast cancers in the same person, or two family members with breast cancers on the same side of the family
- Male breast cancer
- Triple negative type of Breast Cancer (meaning breast cancer carrying no receptors to target)
- Pancreatic cancer and a breast or ovarian cancer in the same person, or on the same side of the family
- Ashkenazi Jewish ancestry with breast, ovarian, or pancreatic cancers
- Two or more relatives with breast cancer, one under age 50
- Three or more relatives with breast cancer at any age
- A previously identified BRCA mutation in any member of the family
Women who carry a BRCA mutation tend to have breast cancers that are triple negative. Triple negative breast cancers are: Estrogen receptor-negative, Progesterone receptor-negative, and HER2/neu-negative. This means there is no receptor on the outside of the cancer cell to target during treatment. These cancers also tend to be more aggressive and have a high chance of metastasis (meaning theyspread to other parts of the body).
To bring some positive light to this discussion, a recent study at the M. D. Anderson Cancer Center showed that triple-negative breast cancer patients with BRCA mutations experienced a significantly lower chance of the cancer coming back after completing treatment. Also a new class of drugs, called PARP inhibitors, has shown promise in BRCA mutations and/or triple negative breast cancers. Even women who were treated with and failed multiple prior chemotherapies responded favorably to these new agents.
It is imperative that women at risk for carrying the deleterious BRCA mutations be identified prior to the development of a BRCA-associated cancer. In the event that this mutation is detected after the development of cancer, then she should be treated with the most up-to-date, new, and robust treatments that oncologists have to offer at this time.
Dr. Kashif Ali earned his MD Degree from Ross University School of Medicine. He completed his residency in Internal Medicine at the Seton Hall University in New Jersey. While at Seton Hall University, he became the Chief Resident and then went on to complete his training in Hematology and Oncology. During this training he was appointed Chief Fellow. Dr. Ali is presently board certified in Internal Medicine, Hematology and Oncology. Dr. Ali is available to see patients in Hematology and Oncology.