Understanding Breast Cancer Risk

All women are at risk for breast cancer -- and most of us think our risk is higher than it actually is.

The commonly cited statistic – that women have a 1 in 8 lifetime risk of breast cancer – is a bit misleading because 1 in 8 women in the United States do not actually get breast cancer. The 1 in 8 number is an estimate of lifetime risk. A woman with average risk has a 1 in 8 chance of getting breast cancer sometime during her life if she lives to be 90. Some women are less likely to get breast cancer, and some have a greater risk. Some will not live to be 90.

A more meaningful way to look at risk is the chance of getting breast cancer during each decade of life. A woman in her twenties has a 1 in 1,837 (0.05%) risk of getting breast cancer, and her risk increases as she ages to a maximum in her seventies of 1 in 26 (3.88%). If you add up the percentages for each decade, you get 13% lifetime risk (1 in 8). During no ten-year period during her lifetime, though, does a woman face a risk of getting breast cancer as high as 1 in 8.

Of course, some women are at greater risk of developing breast cancer. And they, too, overestimate their risk for getting this disease.

Women with a faulty breast cancer gene are said to have “up to” an 85% lifetime risk of getting breast cancer, but according to the National Cancer Institute, the risk ranges from 36% to 87%. As with women who have an average risk, their chance of getting breast cancer increases as they age. (The exception to this is women with close relatives who got breast cancer when they were young.)

Others with a higher than average risk for breast cancer are women diagnosed with precancerous conditions like lobular carcinoma in situ or atypical hyperplasia. Women who have had breast cancer or ductal carcinoma in situ, a noninvasive cancer, are also at increased risk.
It should be noted that many women who are high risk will never get breast cancer. No one knows why they don’t or why some women get breast cancer even though they have no risk factors. The interplay of genetic make-up, age, reproductive history, environmental exposures, and lifestyle determines whether or not we develop breast cancer.

But those of us who are high risk can’t help feeling we’re destined to get breast cancer. Some choose overly aggressive treatment because they can’t live with the possibility that they might get this disease. They get bilateral mastectomies, reducing their risk by 90%. In some cases, this surgery is more drastic treatment than is necessary, and it does not guarantee they will never get breast cancer.

Women do it to ease their fears. Being high risk for breast cancer is more frightening than it should be because of misperceptions about the level of risk for the average woman.

Overestimating Breast Cancer Risk

Whenever I hear that a woman has a 1 in 8 risk of being diagnosed with breast cancer, I cringe. First, because this is a scary statistic. And second, because it is misleading.

It does not mean that 1 in 8 women in the United States will actually get breast cancer. It is an estimation that a woman has a 1 in 8 (12.3%) chance of getting breast cancer during her entire lifetime -- if she lives to the age of 85. Of course, some women die from other causes before they reach 85. The leading cause of death in women is heart disease and the leading cause of cancer death in women is lung cancer, not breast cancer.

The 12.3% figure comes from adding up the average risk women face during each decade of their lives. Some women face a higher or lower risk than average, but according to the American Cancer Society, a woman’s chance of being diagnosed with breast cancer is:

Age
20-29...........0.05%..........1 in 1,837
30-39...........0.43%.............1 in 234
40-49...........1.43%...............1 in 70
50-59...........2.51%...............1 in 40
60-69...........3.51%...............1 in 28
70-79............3.88%..............1 in 26
----------------------------------------------
Lifetime......12.28%.................1 in 8

The lifetime risk is roughly the sum of the risk in each decade. (The math whizzes among us may have noticed that the percentages for each decade do not add up to 12.28%, but to 11.81%. These numbers were taken directly from the American Cancer Society’s Breast Cancer Facts and Figures 2007-2008, and do not include risk to age 85.) What is clear – though a bit mysterious mathematically – is that at no time during her life does a woman face a risk of getting breast cancer as high as 1 in 8. No one should be mislead to think that if she’s sitting in a room with 8 women, one of them is destined to get breast cancer.

I am not among the mathematically inclined, but I do have to question whether it’s valid to add up the risk during different periods to get a picture of overall risk. Suppose we were trying to predict the weather instead of the likelihood of getting breast cancer. If the forecast next week was for a 10% chance of rain each day, you’d expect pleasant weather. But if you added up the risk for each day and estimated that there was a 70% chance of rain next week, you’d be sure to take your umbrella.

Carrying around an umbrella is one thing, but when women are made unduly anxious about breast cancer, they may opt for overly aggressive treatment – prophylactic mastectomy -- when they are diagnosed with precancerous conditions, ductal carcinoma in situ (DCIS), or the breast cancer gene. Hearing you’re high risk for breast cancer becomes even more frightening when you have an inaccurate perception of what average risk is.

Confusion About Lobular Carcinoma In Situ?

Almost every day, someone comes to this blog because they have done a Google search on the terms “LCIS” and “prophylactic mastectomy.” My breast surgeon was surprised that women needed to look this up.

Ideas have changed in the 20 years since she gave me the diagnosis of lobular carcinoma in situ (LCIS) and advised me to have regular check-ups. She added that I would hear about another way to treat LCIS, but left no doubt that her recommendation was careful follow-up. She was firm enough that when I learned the alternative was double mastectomy, I gave it less consideration than I might otherwise have.

At the time, the medical community was evenly divided on whether to recommend careful follow-up for women with LCIS or a bilateral prophylactic mastectomy. (A single mastectomy is not an option because LCIS indicates a risk for breast cancer in both breasts.) These days it would be unusual for doctors to suggest a double mastectomy, but something else may be recommended. Tamoxifen is sometimes used for prevention in women who are high risk for breast cancer.

So why, then, are people Googling “LCIS” and “prophylactic mastectomy?”

I suspect women are told there are options without being told as clearly as I was that one of the choices is by far the most reasonable. When we hear there are various ways to treat a disease, we might assume the most drastic must be the best. In this case it is not.

LCIS is not cancer, and it is not even considered a true precancer because if invasive cancer develops, it does not necessarily arise from the LCIS cells. LCIS is a warning sign that a woman is at risk for breast cancer. It sounds scarier than it is because it is called a carcinoma, or cancer. It got that label when it was first identified years ago under a microscope because the LCIS cells looked like cancer cells. The fact that there were important differences in their biological activity was learned later on.

The danger with invasive cancer is that it can spread outside the breast to other organs. LCIS does not have that capacity and remains in the breast. The phrase “in situ” is Latin for in place – and that is where LCIS stays.

There are some exceptions to favoring careful surveillance for women diagnosed with LCIS. Those who have a strong family history of breast cancer, those who have a defective form of the breast cancer gene, and those who have a type of LCIS called pleomorphic LCIS might take this warning more seriously and act more aggressively.

When the choice is not clear, however, it is wise to go for a second opinion. The best place would be one of the National Cancer Institute approved cancer centers. If there is not one nearby, look for a breast specialist by checking with a large hospital in your area. Friends, family, or your internist or gynecologist may be able to recommend a breast surgeon.

It might also be advisable to get a second opinion for the pathology report on tissue removed during biopsy. My doctor does this because there are sometimes difficulties identifying LCIS on pathology slides.

New Genetic Test for Breast Cancer Risk

The deCODE genetic test for breast cancer risk has hit the market, and here are some reasons to save yourself $1625.

1. No gene can predict that a woman will get breast cancer. Even the better understood breast cancer susceptibility genes, BRCA-1 and BRCA-2, do not indicate that a woman will get breast cancer -- only that her risk is high. The interplay of genes, lifestyle factors, and exposure to environmental hazards determines whether or not a woman develops breast cancer.


2. Scientists question the validity of using this test to predict the risk of getting breast cancer. (The opinions of some noted breast cancer specialists can be found in an article in the Washington Post.) This test may indicate that you have certain genes associated with breast cancer risk, but no one knows what the implications are for having any one of the many combinations of these and other genes.


3. There are ways to reduce breast cancer risk, but doctors do not know which option might work for any particular woman. Medications like Tamoxifen or Evista might be recommended, but they have side effects that a woman would want to avoid unless her risk was extremely high. This test would not be necessary to know that, as family history, the presence of a precancerous condition, or diagnosis with a BRCA gene mutation would indicate high risk.


4. Positive results may cause undue alarm and anxiety. It is frightening to hear you're high risk for breast cancer. Given that the reliability of this test for predicting breast cancer risk is questionable, and that doctors don't really know what to recommend to reduce risk, it seems unwise to subject yourself to hearing that you might be high risk.


5. Negative results could lull you into a false sense of security. These genes are not the only factors that increase breast cancer risk.

Women do not need to know their genetic make-up to understand that they should have regular screening and check-ups. And every woman should strive to have a healthy lifestyle to reduce her risk for breast cancer -- and for heart disease, diabetes, Alzheimer's, and other cancers at the same time.

Carcinoma in situ

A diagnosis of lobular carcinoma in situ (LCIS) or ductal carcinoma in situ (DCIS) is not as scary as it sounds. The Latin term "in situ" means in place. LCIS and DCIS can not spread outside the breast unless they undergo a transformation to become invasive cancer. That capacity for spreading, or metastasizing, is what makes invasive breast cancer dangerous.

The two types of carcinoma in situ are similar in that there are abnormal cells growing within the breast, but the similarities end there. LCIS develops in structures in the breast called lobules, which are the milk-producing glands, while DCIS develops in the ducts that carry milk from these glands.

LCIS serves as a warning sign that a woman is at risk for developing breast cancer, while DCIS is considered a very early stage of breast cancer. DCIS might more accurately be called a precancer, though, because it has no capacity to metastasize as invasive cancer does unless it first undergoes a change. It is thought that DCIS, if left untreated, would not become invasive in approximately half the women who have it, but its presence is taken seriously enough for it to be treated as early cancer.

Depending on how extensive the DCIS is and what its characteristics are, it may be removed surgically with a lumpectomy or a mastectomy, and it may require radiation. The risk of recurrence is very low.

The usual treatment for LCIS is not really treatment, but careful surveillance. Women get regular breast exams and a yearly mammogram. Thirty or forty years ago, LCIS was considered cancer, and women would have a mastectomy after it was diagnosed. It was later determined that LCIS was simply a warning sign that breast cancer could develop in either breast. Both breasts have to be removed for risk to be reduced, but prophylactic mastectomy for LCIS is considered "an overly aggressive approach" according to the National Cancer Institute.

Ideas about carcinoma in situ have changed over the years and are still changing. There is some uncertainty about the implications of having it for any particular woman. No one likes to be told they are high risk for breast cancer or that they have an early stage of the disease, but it is important to understand that there is a distinction between carcinoma in situ and invasive cancer so as not to take more drastic measures than necessary.

Having a bilateral prophylactic mastectomy for either LCIS or DCIS is more than is needed unless there are additional risk factors like having a faulty BRCA gene or a very strong family history of breast cancer.

So why are women diagnosed with LCIS or DCIS told that prophylactic mastectomy is a possibility? Doctors are obligated to describe all options for treating a disease. With carcinoma in situ, as with some others, it is important to understand that the most drastic treatment is not necessarily the best.

Prophylactic Mastectomy: A Cautionary Tale

Hearing you're high risk for breast cancer is frightening. There is uncertainty as to what you should do about it -- and you desperately want to do something. But taking the most drastic step of having both breasts removed is not the right choice for many women. It wasn't for me.
I had no family history of breast cancer and would never have thought I was at risk until a routine mammogram showed a suspicious spot. A biopsy revealed that I had a precancerous condition that put me at high risk for getting breast cancer.
I thought my days were numbered. Adding to my concern was confusion about what this condition was and how it should be treated. Lobular carcinoma in situ (LCIS) is a cancer "in place" that has no potential for spreading outside the breast unless it undergoes a transformation. It is classified as a "Stage 0" breast cancer but is not a true cancer because it lacks the potential to metastasize, or spread.
Now there is more certainty about what women with LCIS should do, but when I was diagnosed almost twenty years ago, the medical community was evenly divided on what to recommend. Around half the doctors surveyed for a study at the time said they would carefully monitor women with LCIS with regular check-ups and mammograms. The other half said they would advise LCIS patients to have both breasts removed.
A double mastectomy for a precancerous condition seemed extreme -- since the treatment for a more threatening invasive cancer would have been a lumpectomy or a single mastectomy. LCIS indicates a potential for developing breast cancer in either breast, so to fully reduce the likelihood of breast cancer, both breasts have to be removed. But even with a double mastectomy, there is no guarantee you won't get breast cancer.
I considered the bilateral mastectomy, but followed the recommendation of my wise and progressive breast surgeon to have careful follow-up. Now most doctors favor this approach, and the women most likely to be grappling with the issue of having prophylactic bilateral mastectomy are those who have been diagnosed with a gene that causes susceptibility to breast cancer. Some are taking the initiative in deciding to have this surgery -- and in many cases, they are ignoring the recommendation of their doctors.
And why shouldn't they, you might ask. They are told their risk for getting breast cancer can be as high as 85%, and they are living with the uncertainty that breast cancer could strike at any time. Many have watched mothers or sisters struggle through surgery, radiation, and chemotherapy. They understandably want no part of that.
But there are reasons they should not rush into having this surgery.

• Some women with the gene will never get breast cancer. The risk of a woman with a susceptibility gene getting breast cancer at some point during her lifetime is 36% to 85%, as compared to a risk of 12.7% in the general population. The risk for women with the gene is often described as being "up to" 85%, but that number represents the worst case scenario.
• These estimates of risk are not etched in stone. They are likely to change as scientists learn more about how these genes lead to breast cancer, just as ideas about LCIS changed. One group has already reported that the risk may be lower than currently believed.
• Scientists are trying to learn why some women with the gene do not get breast cancer, and at some point, they may be able to predict who is at greatest risk and should consider prophylactic mastectomy.
• Women who get bilateral mastectomy can still get breast cancer. The surgery reduces risk by 90%, but does not eliminate it. Breast tissue is spread out in the chest, and some remains after mastectomy.
• There are less drastic ways to reduce breast cancer risk. Tamoxifen and Evista reduce breast cancer risk by around 50%. Some women can reduce their risk with a healthy lifestyle.
• The risk of getting breast cancer increases with age, even in women with a susceptibility gene unless they have close relatives who got breast cancer when young. For women whose mother or sister didn't get breast cancer until close to menopause, though, having breasts removed in their 30's -- as some women are doing -- may be premature.
• No surgery is free of risk, and further surgery may be necessary. Women having mastectomies can develop infections or have bad reactions to drugs, just as with any surgery. Implants need to be replaced periodically.

Of course, bilateral mastectomy may be the wisest choice for some women who have the gene, but it is too drastic a step for many others.