Her first breast cancer may hold some clues, according to a new study, published in the advance online edition of Cancer.

-Not every woman who has breast cancer will get another breast cancer in the opposite breast

“We tried to distill down some of those factors with our study and figure out which ones may be the most important ones, says a professor of surgical oncology at the University of Texas, Anderson Cancer Center.

But the findings don’t amount to a checklist for getting a preventive mastectomy; breast cancer experts say that’s still a personal decision that each patient must weigh with her doctors.

Mastectomy Study

The  study included 542 women who had a mastectomy at the Anderson Cancer Center to remove a cancerous breast, and also chose to get a precautionary mastectomy in the unaffected breast, a procedure called contralateral prophylactic mastectomy.

Immediately after the contralateral prophylactic mastectomy, tests showed that the vast majority of women, about 95%, had no cancer in that breast, and only 1.5% had an invasive tumor in that breast.

Because women typically get preventive mastectomies to curb their future risk, doctor team also followed another 1,574 women who had mastectomy to remove a cancerous breast but chose not to have a preventive mastectomy in their second breast. Over the next four years or so (50 months), only 2.4% of the women developed breast cancer in their remaining breast. It’s not clear how many of those cancers were invasive tumors.

Key Factors

There are three factors that were more common among women with cancer in the breast that they had removed as a precaution. Those factors are:

• Having more than one tumor in the breast that was first diagnosed.
• Having invasive lobular cancer in the breast that was first diagnosed.
• Being at high risk for breast cancer, according to the Gail model.

Invasive lobular breast cancer isn’t common; it accounts for about 5% of all breast cancers. And she notes that the Gail model was designed to gauge future breast cancer risk for women who haven’t been diagnosed with breast cancer; it wasn’t intended for use for breast cancer patients.

Gail model may be a “useful tool” for women with breast cancer, but it will take more studies to confirm that. “We’re hoping to develop a risk calculator that we can put online that would be useful to clinicians and patients,”

“We’re learning more and more that all breast cancers are not the same and they really shouldn’t all be treated the same,”. “We have general guidelines that really help to make sure women get the appropriate treatment, but each individual patient has unique factors and features … that are important to consider.”

Breast Cancer Experts Weigh In

Julie Gralow, director of medical oncology at the Seattle Cancer Care Alliance and an associate professor of oncology at the University of Washington, tells that the above risk factors “make sense,” but the study “doesn’t convince me that we should be recommending” preventive mastectomy based on those factors.

“Nobody would recommend a prophylactic mastectomy in a group that over the next four years only had a 2.4% chance of getting it on the other side,” says Gralow, referring to the comparison group on above study.

Women who have had breast cancer are at “high risk” for another breast cancer, “but ‘high’ is a relative term,” notes Victor Vogel, the American Cancer Society’s national vice president for research.

“Whether the Gail model is the appropriate way to estimate that risk is highly debatable,” Vogel says. “What you’d want is a study in which patients with a first breast cancer had a Gail model score, and then in five years, you look to see whether the Gail model accurately predicted the number of second breast cancers. And I am not aware that any such study has ever been done.”

Gralow and Vogel also point out that when breast cancer is diagnosed, many doctors now perform MRI scans of both breasts. Those scans help show the extent of breast cancer in the affected breast and check the other breast for cancer.

The study started before that practice became common, so not all of the patients got MRI scans before opting for preventive mastectomy. Genetic testing also wasn’t a routine procedure for the patients in the study, and isn’t recommended for most breast cancer patients.

No Rush to Decide

Gralow, and Vogel encourage women to take their time in deciding whether or not to get a contralateral prophylactic mastectomy and to focus on treating the breast cancer that they already know they have.

“A lot of women will come to my office and immediately say, ‘Why don’t you just take both breasts off?’ and I try to explain to them that depending on their risk, not everyone needs that dramatic measure,”. “I always try to get patients to give much more time and consideration to it.”

“There shouldn’t be this sense that we have to do this [preventive mastectomy] right now,”. “This is not urgent, it’s not life-threatening immediately … it can be done after the primary therapy, when you get a little emotional distance from it and you can make these decisions with a calm heart.”

Gralow notes that preventive mastectomy hasn’t been shown to improve breast cancer survival, though it does cut the odds of getting breast cancer again. That’s because if a recurrence happens, chances are it would be found and treated.

Still, “it’s perfectly understandable that maybe women wouldn’t want to go through that a second time,”. “For some women, even a couple percent chance of getting another breast cancer is enough to say, ‘I just don’t want to deal with it.’”

Gralow says she would support a woman who made that choice, as long as the patient understood the risks and benefits. Her advice: “If you’re not sure, you shouldn’t do it, because it’s permanent.”

As in all forms of cancer, the abnormal tissue that makes up breast cancer is the patient’s own cells that have multiplied uncontrollably. Those cells may also travel to locations in the body where they are not normally needed, which means the cancer is malignant.

Breast cancer develops in the breast tissue, primarily in the milk ducts (ductal carcinoma) or glands (lobular carcinoma). The cancer is still called and treated as breast cancer even if it is first discovered after traveling to other areas of the body such as the lungs, liver, or bones. In those cases, the cancer is referred to as metastatic or advanced breast cancer.

Breast cancer usually begins with the formation of a small, confined tumor (lump) and then spreads through channels to the lymph nodes or through the blood stream to other organs. The tumor may also grow and invade tissue around the breast, such as the skin or chest wall. Different types of breast cancer grow and spread at different rates – some take years to spread beyond the breast while other move quickly.

Some lumps are benign (not cancerous). The only safe way to distinguish between a benign lump and cancer is to have the tissue examined by a doctor.

Men can get breast cancer, too, but they account for less than one-half of one percent of all cases. Among women, breast cancer is the most common cancer and the second leading cause of cancer deaths behind lung cancer.

If eight women were to live to be at least 85, one of them would be expected to develop the disease at some point during her life. Two-thirds of women with breast cancer are over 50, and most of the rest are between 39 and 49.

Fortunately, breast cancer is very treatable if detected early. Localized tumors can usually be treated successfully before the cancer spreads; and in nine in 10 cases, the woman will live at least another five years. Experts usually consider a five-year survival to be a cure although late recurrences are not rare.

Once the cancer begins to spread, getting rid of it completely is more difficult, although treatment can often control the disease for years. Improved screening procedures and treatment options mean that at least seven out of 10 women with breast cancer will survive more than five years after initial diagnosis, and half will survive more than 10 years.

What Causes Breast Cancer?

Although the precise causes of breast cancer are unclear, we know what the main risk factors are. Still, most women considered at high risk for breast cancer do not get it, while many who do have no known risk factors. Among the most significant factors are advancing age and a family history of breast cancer. Risk increases slightly for a woman who has had a benign breast lump and increases significantly for a woman who has previously had cancer of the breast or the ovaries.

A woman whose mother, sister, or daughter has had breast cancer is two to three times more likely to develop the disease, particularly if more than one first-degree relative has been affected. Researchers have now identified two genes responsible for some instances of familial breast cancer – called BRCA1 and BRCA2.  About one woman in 200 carries it. Having the gene predisposes a woman to breast cancer but does not ensure that she will get it.

Generally, women over 50 are more likely to get breast cancer than younger women, and African-American women are more likely than Caucasians to get breast cancer before menopause.

A link between breast cancer and hormones is gradually becoming clearer. Researchers think that the greater a woman’s exposure to the hormone estrogen, the more susceptible she is to breast cancer. Estrogen tells cells to divide; the more the cells divide, the more likely they are to be abnormal in some way, possibly becoming cancerous.

A woman’s exposure to estrogen and progesterone rises and falls during her lifetime, influenced by the age she starts and stops menstruating, the average length of her menstrual cycle, and her age at first childbirth. A woman’s risk for breast cancer is increased if she starts menstruating before age 12, has her first child after 30, stops menstruating after 55, or has a menstrual cycle shorter or longer than the average 26-29 days. Current information indicates that the hormones in birth control pills probably do not increase breast cancer risk. Some studies suggest that taking hormone replacement therapy after menopause may increase risk, especially when taken for more than 5 years. The jury is still somewhat out on this matter though. Heavy doses of radiation therapy may also be a factor, but low-dose mammograms pose almost no risk.

The link between diet and breast cancer is debated. Obesity is a noteworthy risk factor and drinking alcohol regularly – more than a couple of drinks a day – may promote the disease. Many studies have shown that women whose diets are high in fat are more likely to get the disease. Researchers suspect that if a woman lowers her daily calories from fat – to less than 20%-30% – her diet may help protect her from developing breast cancer.