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Does Obesity Cause Breast Cancer

What Happens To Cancer Risk After A Person Stops Drinking Alcohol

How does obesity cause cancer? | Cancer Research UK

Most of the studies that have examined whether cancer risk declines after a person stops drinking alcohol have focused on head and neck cancers and on esophageal cancer. In general, these studies have found that stopping alcohol consumption is not associated with immediate reductions in cancer risk. The cancer risks eventually decline, although it may take years for the risks of cancer to return to those of never drinkers.

For example, ex-drinkers still had higher risks of oral cavity and pharyngeal cancers than never drinkers even 16 years after they stopped drinking alcohol, although it was lower than before they stopped drinking . One study estimated that it would take more than 35 years for the higher risks of laryngeal and pharyngeal cancers associated with alcohol consumption to decrease to the level of never drinkers .

General Conclusions On Obesity And Breast Cancer Risk

Obesity neither causes nor increases the risk of breast cancer. Connecting the two conditions is logically flawed when you observe two health effects you cannot logically conclude that one causes the other. Both are the most likely the result of pre-existing genetic causes, and both tend to affect women in the latter half of their lives. Most BMI related studies are done in comparison to a population of normal weight BMI people, with an average age in their early 20s. . Large breast cancer studies, however, tend to focus on women in their 40s and 50s.., by which time many more women have become overweight, and some have developed breast cancer.

A recent study estimated that in the United States, up to 18 000 deaths per year due to breast cancer for women over 50 may not have occurred had the women been able to maintain a BMI under 25 during their adult lives. This conclusion is highly dubious. A more likely observation would be that a certain percentage of women who died of breast cancer, also happened to be obese. It is possible that breast cancer severity is affected by altered hormonal levels influenced by extra fat tissues, but this effect is very small.

For further reading, you may want to visit a cool and handy tool called The Gail Model, which is specifically meant for estimating breast cancer risk. Know your risk now!

What Types Of Cancer Are Caused By Obesity

Being overweight or obese increases the risk of 13 types of cancer:

Breast , bowel, womb, oesophageal , pancreatic, kidney, liver, upper stomach , gallbladder, ovarian, thyroid, myeloma , and meningioma 12,13.

This includes two of the most common types of cancer breast and bowel cancers – and three of the hardest to treat pancreatic, oesophageal and gallbladder cancers.

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Breast Cancer And Weight: What’s The Link

Carrying extra weight increases your risk for 12 cancers. But when itcomes to weight and breast cancer risk, the story gets complicated. Ourexpert explains the link.

The link between excess weight and increased cancer risk is well established. Being overweight or obese increases your risk for 12 cancers, including uterine, kidney, liver and colorectal cancer.

When it comes to breast cancer, the story isn’t so clear. Being overweight does affect your breast cancer risk. But that effect is different before and after menopause.

Confusing? We talked to Karen Basen-Engquist, Ph.D., professor in Behavioral Science at MD Anderson. Here’s what she had to say.

First, how do you know if you are a healthy weight, overweight or obese?

BMI, or body mass index, is a good way to get a general idea if you are a healthy weight. BMI is a tool to compare your height to your weight to see if you fall into one of four ranges: underweight, normal, overweight or obese.

Tips To Reduce Your Cancer Risk:

The public doesn
  • Limit the portion size of your meals and snacks.
  • Eat plenty of fruit, vegetables, legumes, wholegrain and high-fibre foods.
  • Cut out unhealthy snacks and replace with nuts, fruit, yoghurt or cheese.
  • Swap sugary drinks for water.
  • For breakfast, add fruit and yoghurt to wholegrain cereal or serve some veggies with your eggs and toast.
  • Visit gethealthynsw.com.au or call 1300 806 258 for more tips and support.
  • If youve had cancer, visit Life after cancer treatment to find out what support is available.

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How Might Body Weight Affect Cancer Risk

Excess body weight may affect cancer risk in a number of ways, some of which might be specific to certain cancer types. Excess body fat might increase cancer risk by affecting:

  • Inflammation in the body
  • Cell and blood vessel growth
  • Cells’ ability to live longer than they normally would
  • Levels of certain hormones, such as insulin and estrogen, which can fuel cell growth
  • Other factors that regulate cell growth, such as insulin-like growth factor-1
  • The ability of cancer cells to spread

Does Stress Cause Cancer

Theres no conclusive evidence that stress increases your risk of breast cancer.

A number of studies have looked at the links between stress and breast cancer, but there isnt enough evidence to show a clear association.

Stress can be linked to a rise in other lifestyle behaviours, such as being less active or drinking alcohol, which could increase your risk of breast cancer.

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How Can Body Weight Affect Breast Cancer Risk After Menopause

Blood estrogen levels

Before menopause, most estrogens in the body are produced in the ovaries.

After menopause, the ovaries no longer produce much estrogen and estrogens mainly come from fat tissue.

Fat tissue contains an enzyme called aromatase that converts hormones called androgens to estrogens. So, heavier women have higher blood estrogen levels than leaner women .

Women with higher estrogen levels have an increased risk of breast cancer compared to women with lower estrogen levels . So, the extra estrogen likely explains at least some of the increased breast cancer risk among postmenopausal women who are overweight.

Learn more about estrogen and breast cancer risk.

Insulin levels

Women who are heavier tend to have higher levels of insulin in their bodies compared to leaner women .

Some studies have shown an increased risk of breast cancer among postmenopausal women with high levels of insulin, including women with type 2 diabetes .

Among premenopausal women, a possible link between insulin levels and breast cancer risk is less clear .

These topics are under study.

Does It Matter Where The Fat Is Stored In The Body

How does obesity cause cancer?

Yes, it can matter. When too much fat is carried around the middle of the body, near the stomach, it may be more harmful. Some research shows that people who carry a lot of fat around their middle are at an even greater risk of certain types of cancers.

It isn’t clear exactly why this is, but it could be to do with how quickly certain chemicals from fat can get into the blood.

The NHS recommends trying to lose weight if your BMI is above 25 or your waist circumference is over 94cm or 80cm .

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Why Does Weight Affect Breast Cancer Risk

Hormones such as oestrogen help some breast cancers to grow. After the menopause, the ovaries stop producing oestrogen, so levels in the body drop.

Women who are overweight or obese after the menopause have a higher level of oestrogen in their bodies, which may encourage the growth of some breast cancers. This is because the hormone is also made by fatty tissue.

Being overweight or obese also alters the levels of other hormones, including insulin .

These changes might increase the chance of breast cancer developing.

Paradoxical Effects Of Body Mass Index On Breast Cancer Risk In Relation To Menopausal Status

Overweight is defined as a body mass index . The association between breast cancer risk and excess weight varies according to menopausal status , with independent studies reporting a negative correlation between obesity and risk in premenopausal women . Indeed, a pooled analysis of 7 studies including a total of 337,819 women reported a risk ratio of 0.54 for breast cancer risk when comparing premenopausal women with BMI > 31 kg/m2 versus those with a BMI of 21 kg/m2 . Likewise, a separate meta-analysis involving 9 studies also demonstrated an inverse correlation between obesity and per unit increase in BMI with regards breast cancer risk in premenopausal women . Similar findings were reported in an independent meta-analysis consisting of 34 datasets of women in which breast cancer risk was investigated relative to BMI . In total, breast cancer was reported in 7,930 premenopausal and 23,909 postmenopausal women and, overall, breast cancer risk was shown to be reduced by approximately 8% per 5 kg/m2 BMI increase in premenopausal women . In contrast, the risk was increased in postmenopausal women . This latter meta-analysis undertaken by Renehan and colleagues included prospective cohort and large observational studies, and provides a stronger level of evidence than earlier case-control reports.

Table 1 Summary of large studies/analyses investigating the association of obesity with breast cancer according to menopausal status.

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Sugar & The Western Diet

Additionally, the dietary pattern that most often goes hand-in-hand with increased refined sugar intake is associated with the Western so-called unhealthy diet and includes red or processed meats, refined grains, sweets, and high-fat dairy products, all of which have been associated with increased cancer risk.

Conversely, a prudent and healthy diet pattern which includes higher intake of vegetables, fruits, fish, poultry, whole grains, and low-fat dairy products has been shown to decrease cancer risk. In specific regard to breast cancer, the evidence has been less consistent, with some reports supporting the prudent dietary pattern as being inversely associated with risk of breast cancer while others found no association. However, dietary fat, alcohol, and processed and red meat intakes have more consistently been attributed to an increased risk of breast cancer.5

Furthermore , when consuming sugar and empty calories takes the place of more nutritious and cancer-fighting foods, we deprive ourselves of the opportunity to optimize our bodies and change the scenery that is developing or already in place.

Therefore, instead of focusing on what feeds cancer, lets invert our lens to view what enhances an internal environment supportive to health.

How Do We Know Obesity Causes Cancer

Does obesity cause cancer?

There is lots of high-quality research showing the link between excess weight and cancer.

There are consistent results from decades of research involving millions of people. We see more cancer cases in groups that are overweight compared to groups that are a healthy weight.

The risk increases the more weight is gained, so we can be more sure the link is real . And there are good explanations for how extra fat cells in the body could cause cancer. We can confidently rule out other explanations .

International organisations like the International Agency for Research on Cancer and the World Cancer Research Fund agree.

A person’s risk of cancer depends on lots of different factors. This includes things you can’t change like your age and genes. Factors like smoking, obesity and UV rays also affect our cancer risk.

This doesn’t mean that everybody who is overweight, smokes or spends too much time in the sun will develop cancer. But, they are more likely to get cancer.

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Whats My Risk Of Developing Cancer If I’m Overweight Or Obese

Being overweight doesnt mean that you’ll definitely develop cancer. But if you are overweight you are more likely to get cancer than if you are a healthy weight. Your exact risk will depend on lots of factors, including things you can’t change such as your age and genetics.

Losing weight or avoiding putting on more weight can help reduce the risk of cancer.

People keeping a healthy weight could prevent around 22,800 cases of cancer every year in the UK.

There are lots of other benefits to keeping a healthy weight including having increased energy and reducing the risk of conditions such as heart disease, stroke and osteoarthritis.

Extra fat in the body doesnt just sit there, its active, sending out signals to the rest of your body. These signals can tell cells in our body to divide more often, which can lead to cancer.

The signals released by fat cells can affect:

These are the main ways scientists have identified so far, but research continues to find out more about the ways extra body fat can cause cancer.

Which Cancers Are Related To Obesity

Being overweight and having obesity are linked with a higher risk of getting 13 kinds of cancer. These cancers include

  • Adenocarcinoma of the esophagus.
  • Meningioma .
  • Multiple myeloma.

Other risk factors can also contribute to these cancers. Some of these risk factors are hormone levels, changes in genes, long-lasting infections, and tobacco and alcohol use. Being overweight or having obesity doesnt mean that someone will definitely get cancer. But it does mean that they are more likely to get cancer than if they kept a healthy weight.

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Weight Gain After Menopause

Its not just the weight a woman gains after age 18 that seems important to risk. The weight a woman gains after menopause also appears to be linked to an increased risk of breast cancer .

One large study showed women who gained 20 pounds or more after menopause had an 18 percent higher risk of breast cancer compared to those who gained little or no weight after menopause .

For a summary of research studies on weight gain and breast cancer, visit the Breast Cancer Research Studies section.

How Does The Combination Of Alcohol And Tobacco Affect Cancer Risk

The Link Between Obesity and Breast Cancer

Epidemiologic research shows that people who use both alcohol and tobacco have much greater risks of developing cancers of the oral cavity, pharynx , larynx, and esophagus than people who use either alcohol or tobacco alone. In fact, for oral and pharyngeal cancers, the risks associated with using both alcohol and tobacco are multiplicative that is, they are greater than would be expected from adding the individual risks associated with alcohol and tobacco together .

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Effects Of Tamoxifen For Obese Women With Breast Cancer

Tamoxifen is most frequently used as chemical therapy for inhibiting growth and recurrence of breast cancer. This drug is oriented towards a womans hormonal system and is a highly effective treatment for HER2 positive patients. For obese women, there is no difference in success rates or recurrence compared to women of normal weight, but, there is a suggestion of an increased risk of breast cancer development in the opposite breast. There may also be an increased risk for obese women of developing other cancers. However, these developments cannot be conclusively traced to the tamoxifen and are far more likely to be caused by pre-existing genetic factors associated with both cancer development and obesity, to begin with.

Physical Activity Associated With Reduced Breast Cancer Risk

In the Women’s Health Initiative study of 155,723 women who were followed over a median of 7.3 years, the risk of breast cancer was lower by 15% to 23% in the tertile with the highest recreational physical activity relative to the lowest tertile. Similarly, among 25,624 Norwegian women, over 4 hours of leisure time PA per week was associated with a 37% lower risk , with an inverse dose response between PA and risk. Two casecontrol studies also associated higher recreational PA versus none with a 30% to 60% lower breast cancer risk , with a significant decrease in premenopausal, receptornegative cancers .

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Obesity Causes Breast Cancer 15 Breast Cancer Rumours Debunked

Breast cancer awareness is on the rise and so are the tumorous rumors surrounding it. See how many of the following 15 myths/facts you know or have heard of to avoid serious repercussions.

1. Myth: If I had a normal mammogram, then I neednt worry about breast cancer.

Fact: Mammograms fail to detect around 10% to 20% of breast cancers. Just because one exam comes back normal doesnt mean breast cancer would not develop later. To be safe, conduct self-examinations, paying particular attention to any changes in how your breasts look or feel.

2. Myth: Breast implants can raise your cancer risk.

Fact: Breast implants wouldnt increase your chance of getting breast cancer, according to research.However, additional X-rays are sometimes needed for more thorough examination of the breast tissue because standard mammograms dont always work well on women with implants.

3. Myth: You cant get breast cancer after a mastectomy.

Fact: Some women get breast cancer at the site of the scar after a mastectomy. Angelina Jolie underwent an elective double mastectomy after tests revealed that she carried a breast cancer causing gene. However, she still has the possibility to get breast cancer though the risk is reduced by an average of 90% after prophylactic mastectomy.

4. Myth: Obesity doesn’t play a role in breast cancer.

5. Myth: Having an abortion increases your risk of getting breast cancer.

6. Myth: Wearing an underwire bra increases your breast cancer risk.

Does Body Weight Affect Cancer Risk

Does obesity cause cancer?

Being overweight or obese is clearly linked to an overall increased risk of cancer. According to research from the American Cancer Society, excess body weight is thought to be responsible for about 11% of cancers in women and about 5% of cancers in men in the United States, as well as about 7% of all cancer deaths.

Being overweight or obese is clearly linked with an increased risk of many types of cancer, including:

  • Breast cancer
  • Colon and rectal cancer
  • Endometrial cancer
  • Esophagus cancer
  • Meningioma

Being overweight or obese might also raise the risk of other cancers, such as:

  • Non-Hodgkin lymphoma
  • Cancers of the mouth, throat, and voice box
  • Aggressive forms of prostate cancer

The link to body weight is stronger for some cancers than for others. For example, excess body weight is thought to be a factor in more than half of all endometrial cancers, whereas it is linked to a smaller portion of other cancers.

The links between body weight and cancer are complex and are not yet fully understood. For example, while studies have found that excess weight is linked with an increased risk of breast cancer in women after menopause, it does not seem to increase the risk of breast cancer before menopause. The reasons for this are not clear.

Clearly, more research is needed to better define the links between body weight and cancer.

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