Factors of unproven effect on breast cancer risk

Diet and vitamin intake

Many studies have looked for a link between certain diets and breast cancer risk, but so far the results have been conflicting. Some studies have indicated that diet may play a role, while others found no evidence that diet influences breast cancer risk. Studies have looked at the amount of fat in the diet, intake of fruits and vegetables, and intake of meat. No clear link to breast cancer risk was found.

Studies have also looked at vitamin levels, again with inconsistent results. Some studies actually found an increased risk of breast cancer in women with higher levels of certain nutrients. So far, no study has shown that taking vitamins reduces breast cancer risk. This is not to say that there is no point in eating a healthy diet. A diet low in fat, low in red meat and processed meat, and high in fruits and vegetables may have other health benefits.

Most studies have found that breast cancer is less common in countries where the typical diet is low in total fat, low in polyunsaturated fat, and low in saturated fat. But many studies of women in the United States have not linked breast cancer risk to dietary fat intake. Researchers are still not sure how to explain this apparent disagreement. It may be at least partly due to the effect of diet on body weight (see below). Also, studies comparing diet and breast cancer risk in different countries are complicated by other differences (such as activity level, intake of other nutrients, and genetic factors) that might also alter breast cancer risk.

More research is needed to better understand the effect of the types of fat eaten on breast cancer risk. But it is clear that calories do count, and fat is a major source of calories. High-fat diets can lead to being overweight or obese, which is a breast cancer risk factor. A diet high in fat has also been shown to influence the risk of developing several other types of cancer, and intake of certain types of fat is clearly related to heart disease risk.

Antiperspirants

Internet e-mail rumors have suggested that chemicals in underarm antiperspirants are absorbed through the skin, interfere with lymph circulation, and cause toxins to build up in the breast, eventually leading to breast cancer.

There is very little laboratory or population-based evidence to support this rumor. One small study has found trace levels of parabens (used as preservatives in antiperspirants and other products), which have weak estrogen-like properties, in a small sample of breast cancer tumors. However, the study did not look at whether parabens caused the tumors. This was a preliminary finding, and more research is needed to determine what effect, if any, parabens may have on breast cancer risk. On the other hand, a large population-based study found no increase in breast cancer in women who used underarm antiperspirants and/or shaved their underarms.

Bras

Internet e-mail rumors and at least one book have suggested that bras cause breast cancer by obstructing lymph flow. There is no good scientific or clinical basis for this claim. Women who do not wear bras regularly are more likely to be thinner or have less dense breasts, which would probably contribute to any perceived difference in risk.

Induced abortion

Several studies have provided very strong data that neither induced abortions nor spontaneous abortions (miscarriages) have an overall effect on the risk of breast cancer. For more detailed information, see the separate American Cancer Society.

Breast implants

Several studies have found that breast implants do not increase the risk of breast cancer, although silicone breast implants can cause scar tissue to form in the breast. Implants make it harder to see breast tissue on standard mammograms, but additional x-ray pictures called implant displacement views can be used to examine the breast tissue more completely.

Breast implants may be linked to a rare type of lymphoma called anaplastic large cell lymphoma. This lymphoma has rarely been found in the breast tissue around the implants. So far, though, there are too few cases to know if the risk of this lymphoma is really higher in women with implants.

Chemicals in the environment

A great deal of research has been reported and more is being done to understand possible environmental influences on breast cancer risk.

Compounds in the environment that studies in lab animals have found to have estrogen-like properties are of special interest. These could in theory affect breast cancer risk. For example, substances found in some plastics, certain cosmetics and personal care products, pesticides, and PCBs (polychlorinated biphenyls) seem to have such properties.

Although this issue understandably invokes a great deal of public concern, at this time research does not show a clear link between breast cancer risk and exposure to these substances. Unfortunately, studying such effects in humans is difficult. More research is needed to better define the possible health effects of these and similar substances.

Tobacco smoke

For a long time, studies found no link between cigarette smoking and breast cancer. In recent years though, some studies have found that smoking might increase the risk of breast cancer. The increased risk seems to affect certain groups, such as women who started smoking when they were young. In 2009, the International Agency for Research on Cancer concluded that there is limited evidence that tobacco smoking causes breast cancer.

An active focus of research is whether secondhand smoke increases the risk of breast cancer. Both mainstream and secondhand smoke contain chemicals that, in high concentrations, cause breast cancer in rodents. Chemicals in tobacco smoke reach breast tissue and are found in breast milk.

The evidence on secondhand smoke and breast cancer risk in human studies is controversial, at least in part because the link between smoking and breast cancer is also not clear. One possible explanation for this is that tobacco smoke may have different effects on breast cancer risk in smokers compared to those who are just exposed to secondhand smoke.

A report from the California Environmental Protection Agency in 2005 concluded that the evidence about secondhand smoke and breast cancer is "consistent with a causal association" in younger, mainly pre-menopausal women. The 2006 US Surgeon General's report, The Health Consequences of Involuntary Exposure to Tobacco Smoke, concluded that there is "suggestive but not sufficient" evidence of a link at this point. In any case, this possible link to breast cancer is yet another reason to avoid secondhand smoke.

Night work

Several studies have suggested that women who work at night, such as nurses on a night shift, may have an increased risk of developing breast cancer. This is a fairly recent finding, and more studies are looking at this issue. Some researchers think the effect may be due to changes in levels of melatonin, a hormone whose production is affected by the body's exposure to light, but other hormones are also being studied.

Breast Cancer

The importance of finding breast cancer early

The goal of screening exams for early breast cancer detection is to find cancers before they start to cause symptoms.Screening refers to tests and exams used to find a disease, such as cancer, in people who do not have any symptoms. Early detection means using an approach that lets breast cancer get diagnosed earlier than otherwise might have occurred.

Breast cancers that are found because they are causing symptoms tend to be larger and are more likely to have already spread beyond the breast. In contrast, breast cancers found during screening exams are more likely to be smaller and still confined to the breast. The size of a breast cancer and how far it has spread are some of the most important factors in predicting the prognosis (outlook) of a woman with this disease.

Most doctors feel that early detection tests for breast cancer save thousands of lives each year, and that many more lives could be saved if even more women and their health care providers took advantage of these tests. Following the American Cancer Society's guidelines for the early detection of breast cancer improves the chances that breast cancer can be diagnosed at an early stage and treated successfully.

What are the risk factors for breast cancer?

A risk factor is anything that affects your chance of getting a disease, such as cancer. Different cancers have different risk factors. For example, exposing skin to strong sunlight is a risk factor for skin cancer. Smoking is a risk factor for cancers of the lung, mouth, larynx (voice box), bladder, kidney, and several other organs.

But risk factors don't tell us everything. Having a risk factor, or even several, does not mean that you will get the disease. Most women who have one or more breast cancer risk factors never develop the disease, while many women with breast cancer have no apparent risk factors (other than being a woman and growing older). Even when a woman with risk factors develops breast cancer, it is hard to know just how much these factors might have contributed to her cancer.

There are different kinds of risk factors. Some factors, like a person's age or race, can't be changed. Some are related to personal behaviors such as smoking, drinking, and diet. Still others are linked to cancer-causing factors in the environment. Some factors influence risk more than others, and your risk for breast cancer can change over time, due to factors such as aging or lifestyle changes.

Shigeaki Hinohara

At the age of 98, Shigeaki Hinohara is one of the world’s longest-serving physicians and educators. Hinohara’s magic touch is legendary: Since 1941 he has been healing patients at St. Luke’s International Hospital in Tokyo and teaching at St. Luke’s College of Nursing.

After World War II, he envisioned a world-class hospital and college springing from the ruins of Tokyo; thanks to his pioneering spirit and business savvy, the doctor turned these institutions into the nation’s top medical facility and nursing school. Today he serves as chairman of the board of trustees at both organizations.

Always willing to try new things, he has published around 150 books since his 75th birthday, including oneLiving Long, Living Good that has sold more than 1.2 million copies. As the founder of the New Elderly Movement, Hinohara encourages others to live a long and happy life, a quest in which no role model is better than the doctor himself.

Here now, in his own words, is advice on this doctor of long life on how to live a long life.

Energy comes from feeling good, not from eating well or sleeping a lot. We all remember how as children, when we were having fun, we often forgot to eat or sleep. I believe that we can keep that attitude as adults, too. It’s best not to tire the body with too many rules such as lunchtime and bedtime.

All people who live long – regardless of nationality, race or gender — share one thing in common: None are overweight. For breakfast I drink coffee, a glass of milk and some orange juice with a tablespoon of olive oil in it. Olive oil is great for the arteries and keeps my skin healthy. Lunch is milk and a few cookies, or nothing when I am too busy to eat. I never get hungry because I focus on my work. Dinner is veggies, a bit of fish and rice, and, twice a week, 100 grams of lean meat.

Always plan ahead. My schedule book is already full until 2014, with lectures and my usual hospital work. In 2016 I’ll have some fun, though: I plan to attend the Tokyo Olympics!

There is no need to ever retire, but if one must, it should be a lot later than 65. The current retirement age was set at 65 half a century ago, when the average life-expectancy in Japan was 68 years and only 125 Japanese were over 100 years old. Today, Japanese women live to be around 86 and men 80, and we have 36,000 centenarians in our country. In 20 years we will have about 50,000 people over the age of 100.

Share what you know. I give 150 lectures a year, some for 100 elementary-school children, others for 4,500 business people. I usually speak for 60 to 90 minutes, standing, to stay strong.

When a doctor recommends you take a test or have some surgery, ask whether the doctor would suggest that his or her spouse or children go through such a procedure. Contrary to popular belief, doctors can’t cure everyone. So why cause unnecessary pain with surgery? I think music and animal therapy can help more than most doctors imagine.

To stay healthy, always take the stairs and carry your own stuff. I take two stairs at a time, to get my muscles moving.

My inspiration is Robert Browning’s poem “Abt Vogler.” My father used to read it to me. It encourages us to make big art, not small scribbles. It says to try to draw a circle so huge that there is no way we can finish it while we are alive. All we see is an arch; the rest is beyond our vision but it is there in the distance.

Pain is mysterious, and having fun is the best way to forget it. If a child has a toothache, and you start playing a game together, he or she immediately forgets the pain. Hospitals must cater to the basic need of patients: We all want to have fun. At St. Luke’s we have music and animal therapies, and art classes.

Don’t be crazy about amassing material things. Remember: You don’t know when your number is up, and you can’t take it with you to the next place.

Hospitals must be designed and prepared for major disasters, and they must accept every patient who appears at their doors. We designed St. Luke’s so we can operate anywhere: in the basement, in the corridors, in the chapel. Most people thought I was crazy to prepare for a catastrophe, but on March 20, 1995, I was unfortunately proven right when members of the Aum Shinrikyu religious cult launched a terrorist attack in the Tokyo subway. We accepted 740 victims and in two hours figured out that it was sarin gas that had hit them. Sadly we lost one person, but we saved 739 lives.

Science alone can’t cure or help people. Science lumps us all together, but illness is individual. Each person is unique, and diseases are connected to their hearts. To know the illness and help people, we need liberal and visual arts, not just medical ones.

Life is filled with incidents. On March 31, 1970, when I was 59 years old, I boarded the Yodogo, a flight from Tokyo to Fukuoka. It was a beautiful sunny morning, and as Mount Fuji came into sight, the plane was hijacked by the Japanese Communist League-Red Army Faction. I spent the next four days handcuffed to my seat in 40-degree heat. As a doctor, I looked at it all as an experiment and was amazed at how the body slowed down in a crisis.

Find a role model and aim to achieve even more than they could ever do. My father went to the United States in 1900 to study at Duke University in North Carolina. He was a pioneer and one of my heroes. Later I found a few more life guides, and when I am stuck, I ask myself how they would deal with the problem.

It’s wonderful to live long. Until one is 60 years old, it is easy to work for one’s family and to achieve one’s goals. But in our later years, we should strive to contribute to society. Since the age of 65, I have worked as a volunteer. I still put in 18 hours seven days a week and love every minute of it.