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【medical-news】家族史只是乳腺癌的病因之一
DR. MARLA SHAPIRO
When I was first diagnosed with breast cancer, one of the most frequent questions I would get was whether I had a family history of breast cancer. I do not. Mystified, questioners would throw up their hands and ask: "Why, then, did you get breast cancer?"
Family history is only one factor that plays a role in this complex disease. As the Canadian Cancer Society points out, as many as 20 per cent of women with breast cancer will have a family history of the disease, but only 5 per cent of women are born with a specific genetic mutation -- BRCA1 or BRCA2 -- that has been clearly linked to an elevated risk of breast cancer as well as to ovarian cancer.
A woman with this particular genetic defect faces an 80-per-cent chance of developing breast cancer at some point in her lifetime.
By contrast, a typical woman's lifetime risk is roughly 11 per cent.
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So, there is a big difference between having a member of your family with breast cancer and being born with this high-risk gene.
Essentially, women with a family history, but not an inherited gene defect, are thought to either have a negligible or moderate increase in risk.
After I was diagnosed, it was important for me to be clear that I was "gene negative" and that my daughters might face a moderate increase risk over the general population -- rather than the greatly increased "gene positive" risk.
It is critical for women to understand where they might lie along this continuum of risk. Most women greatly overestimate their risk when it comes to breast cancer in terms of their family history.
Breast cancer is, indeed, the most common cancer among women, with all of them being at risk. It is estimated that one out of every nine Canadian women will eventually develop breast cancer.
That said, risk actually goes up with age. For instance, at 30, four out of 1,000 women will get breast cancer over the next 10-year period. At the age of 50, 20 out of 1,000 women will develop breast cancer within 10 years. And by the age of 70, the number is 30 out of 1,000.
Known risk factors do include family history; a previous diagnosis of atypical hyperplasia (abnormal cells) or lobular carcinoma in situ (a cancer that starts in the glands that produce milk); radiation therapy to the chest before the age of 30 to treat an earlier cancer; and high alcohol intake. Hormonal factors also play a role. Risk factors include not having been pregnant before 30; having periods before the age of 12; experiencing menopause after 51; being overweight after menopause; and use of hormone replacement therapy.
But many women who get breast cancer have no known risk factors at all.
And many questions remain about specific dietary risk factors, the role of inactivity, environmental toxins and not breast feeding.
As physicians, we begin to wonder about the role of inherited breast cancer when we see cases of breast or ovarian cancer in several members on the same side of the family -- and it can be either your mother or your father's side.
Being diagnosed with breast cancer before 50 might be suggestive of a genetic risk. As well, having a family history of both breast and ovarian cancer increases the index of concern -- especially for someone of Jewish ancestry. (The BRCA1 and BRCA2 mutations are more common among certain Jewish populations.) And if a male family member develops breast cancer -- a rare event -- it may point to an elevated inherited risk.
All these situations can ring alarm bells, but they don't necessarily mean the breast cancer arose from an inherited genetic mutation.
All women should be aware of possible signs of breast cancer. Among experts in the field, there is agreement that breast cancer can appear as a lump or even an area of thickening in the breast or your armpit, where lymph nodes drain the breast tissue. If you notice a change in appearance of the breast such as size or shape, dimpling or puckering, that is also of concern. Any discharge or bleeding from the nipple should be investigated.
Lifestyle is important to helping reduce the risk of breast cancer. Make sure you eat a well-balanced diet and don't smoke. Maintain your weight, exercise routinely and avoid drinking excessive amounts of alcohol.
Talk to your doctor about when and how often to have a mammogram. Make sure you have regular breast examinations and be vigilant about any changes in your body.
My patients often tell me that they didn't go for their mammogram because they didn't have the time. That is not a good excuse. Make it a priority. Early detection can save your life.
Dr. Marla Shapiro can be seen Tuesdays on CTV's Canada AM. Her book, Life in the Balance: My Journey with Breast Cancer, was published recently by HarperCollins Canada. For more information, see http://www.drmarla.ca
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作者:admin@医学,生命科学 2011-01-02 05:14
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