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The American Cancer Society

Can Vitamin D prevent cancer?

June 16, 2015

By Marji McCullough, ScD, RD

You may be aware that Vitamin D is important for helping make strong bones. But vitamin D often appears in the media because of its potential role in a host of other health effects, from preventing cancer, diabetes, and heart disease to simply living longer.  However, most of these "non-skeletal" (not having to do with your bones) roles of vitamin D are not clearly established and remain a topic of active investigation and debate. To add to the confusion, several recent scientific reviews of the vast data on vitamin D arrived at different conclusions about whether it helps prevent disease or not.

In this blog, I am going to focus on the evidence on vitamin D and cancer prevention, highlight some key unresolved questions, and give some advice to consider while we await more solid answers (which may take a while).

Where does vitamin D come from?


People can get vitamin D from exposure to sunlight, from certain foods, and from supplements.

Current vitamin D recommendations from the Institute of Medicine (IOM), the organization tasked with developing the Recommended Dietary Allowances (RDAs), are 600 International Units (IU) per day for most adults, and 800 IU of vitamin D per day for those over age 70. Very high doses of vitamin D over a long period of time can be toxic, so the IOM recommends that no one should exceed 4,000 IU/day. 

Vitamin D is found naturally in very few foods, including cod liver oil, fatty fish like sardines or salmon, and in smaller amounts in eggs and leafy greens. In the U.S., vitamin D is added to milk, some yogurts, orange juices, and cereals. One cup of milk or yogurt contains about 100 IU, whereas fatty fish contains about 500 IU per serving. Read about other sources of vitamin D. Vitamin D supplements are available in a range of doses. 

Sun exposure can provide a wallop of vitamin D, depending on amount of skin exposed, skin tone, time of day, time of year, location, and a variety of other factors. For example, a Caucasian adult wearing a bathing suit exposed to enough sun to have a light pink sunburn has received roughly 10,000-20,000 IU of vitamin D. It takes dark-skinned individuals 5-10 times longer to form the vitamin because of higher concentrations of melanin in the skin, and dark-skinned individuals often have lower vitamin D levels. Other factors that can influence vitamin D formation in the skin include use of sunscreens and sun-protective clothing (because they block UV rays). 

But don't look to the sun as a source of vitamin D because the same UV radiation that forms vitamin D in the skin also burns the skin and can lead to skin cancer. Studies have not identified a level of sun exposure that is safe for avoiding skin cancer. The American Cancer Society recommends limiting sun exposure to prevent skin cancer, including melanoma (the most serious type of skin cancer). 

What the studies say

It has been suggested that vitamin D itself may prevent, or even increase the risk for, some forms of cancer. Different types of studies are used to understand if this is true. All have their strengths and weaknesses and add a piece to the puzzle.

Laboratory studies provide some strong biological evidence to support a role for vitamin D in cancer prevention. Vitamin D can "turn on" or "turn off" a host of genes, including some that regulate cell growth, limit inflammation, and reduce levels of a signaling protein that can allow cancer cells to spread. The exact role of vitamin D in these processes is a very active area of research.

Observational Studies


In humans, the idea that vitamin D might help protect against cancer first came from studies that mapped cancer death rates in the US by region. These studies showed that Northern states, where sun exposure was lowest, had higher death rates from several different cancers compared to the Southern, sunnier states. Because the sun is a source of vitamin D, scientists thought that vitamin D might protect against cancer. However, different cancer rates by region also may be due to other factors that vary among people living in different parts of the country.

So far, the most support for a role of vitamin D comes from prospective studies of colorectal cancer (includes both colon and rectal cancer). In several studies, compared to people with low blood vitamin D levels, people with higher blood levels have a significantly lower risk of colorectal cancer. However, there are inconsistencies in results across studies, potentially due to different methods used, such as how vitamin D was measured.  An ongoing study, called the "Vitamin D Pooling Project of Breast and Colorectal Cancer" is carefully measuring blood levels of vitamin D and examining their association with colorectal and breast cancer in 21 prospective studies, using the same methods. These findings should be published in the next year. 

Observational studies of vitamin D and risk of other cancers do not provide clear evidence of benefit. In a combined analysis from 10 prospective cohort studies, the amount of vitamin D in the blood before diagnosis was not associated (no link was found) with the risk of kidney, lymphoid, ovarian, endometrial, or upper gastrointestinal cancers like stomach or esophagus. For other cancers, including prostate and pancreas, studies have had inconsistent results, some even suggesting increased risk of cancer in those with the highest levels.

A strength of observational prospective cohort studies is that they can typically examine wide ranges of vitamin D in the blood that occur naturally in a population. Their main limitation is that they cannot prove that it's the vitamin D in the blood that really prevents cancer. For example, people with low vitamin D levels may also tend to be less physically active and more overweight or obese, both of which are risk factors for certain cancers. For this reason, researchers conducting observational studies collect detailed information on other risk factors and account for them when they're examining the results.  

Randomized Controlled Trials (RCTs)


When conducted well, RCTs can prove if something prevents disease because people are randomly assigned to get vitamin D or a placebo (sugar pill). The randomization helps to ensure that on average people are more alike in other ways (e.g. body weight, physical activity, and other known or unknown risk factors), so researchers can isolate the effect of the vitamin D supplement. But these studies are very expensive and logistically difficult, and may not study the right dose, for the right amount of time, in the right (susceptible) population.   

So far, a large RCT did not find that 400 IU vitamin D combined with calcium lowered colorectal or breast cancer risk. In this study, women were allowed to take their own supplements, and by the end of the trial, most were. In other words, the placebo group as well as the intervention group were exposed to vitamin D, increasing the risk of results that aren't significant (null results). 

Other RCTs of vitamin D that reported on development of cancer or death from cancer had very small sample sizes and did not provide conclusive results. For some of these trials, the initial goal was to study bone health, not cancer, increasing the likelihood of "chance" findings. There are currently a handful of larger trials underway, including the large U.S. VITAL trial, which will examine vitamin D and fish oil supplements in relation to cancer outcomes and heart disease. Study results are not expected for several years.

What to do in the meantime?


The key for research will be to identify the amount of vitamin D that may lower the risk of certain diseases, but not increase the risk of others. Until we know more, make sure you meet the IOM recommendations for bone health of 600 IU for most adults or 800 IU of vitamin D/day for those over age 70. Even for people who are not exposed to the sun, the recommended doses are thought to be enough for 97.5% of people in the US. Depending on your health status, your doctor may choose to measure how much vitamin D you have in your blood, but routine vitamin D measurements are currently not recommended by any agency for cancer prevention or to avoid other serious illnesses.

Bottom line: we don't know yet if vitamin D can help prevent cancer or other diseases, but we're working on finding out. In the meantime, make sure to meet the IOM recommendations for bone health through food choices as much as you can, and discuss with your health care provider whether you need a supplement to help.

 

McCullough is strategic director of nutritional epidemiology for the American Cancer Society.

World No Tobacco Day is about Driving Down Tobacco Use

May 28, 2015

By Jeffrey Drope, PhD


May 31 is World No Tobacco Day, an important annual event when we pause to reflect on how to move the world away from tobacco use and toward improved public health.  

Tobacco is one of the leading risk factors for non-communicable diseases, including cancer - 32% of all cancer deaths in the United States, including a staggering 87% of lung cancer deaths, are attributable to tobacco use. Tobacco use is also one of the most preventable causes of cancer deaths.  

This year's World No Tobacco Day theme is illicit trade - tobacco products produced, exported, imported, purchased, sold, or possessed illegally. While illicit trade in tobacco products is undoubtedly troubling from a number of perspectives, including lost tax revenue for governments, increased revenue to tobacco companies, and links to organized crime and possibly terrorism, it's important to look at the whole picture. The tobacco industry consistently tries to claim that strong tobacco control policies increase illicit trade. But, in fact, the single best way to fight the illicit trade in tobacco products is to redouble efforts to use what we already know works to drive down the use of all cigarettes, legal and illegal. Such practices include:

  • increasing tobacco excise taxes,
  • requiring graphic warning labels on tobacco packaging,
  • making laws to ban tobacco marketing and
  • demanding smoke-free public and work places and anywhere where children might be present.

It's also important to make very clear some fundamental truths about illicit trade. More...

Recent progress in cancer research, prevention, and treatment

April 22, 2015

By Fadlo R. Khuri, MD, FACP

2014 was another banner year for cancer research, particularly in the areas of treatment, prevention, and early detection. While there were several significant spheres of progress, we find the following five major advances particularly noteworthy.   

Targeted therapies

First is the development of new targeted therapies for cancer. Targeted therapies specifically block key molecules that are crucial for cancer cell growth and survival.

The promise of such therapies was first established about 15 years ago by the development of imatinib (Gleevec), which blocks the oncogene (cancer-promoting gene) responsible for development of chronic myelogenous leukemia (CML), and led to dramatic responses in patients with this cancer. Many more targeted agents have since been developed. This development has been greatly helped in recent years by the sequencing of the human and the cancer genome, which has led to a more complete understanding of genes that drive cancer. 

Targeted agents have transformed modern cancer care by keeping cancer under control for longer periods of time and reducing side effects. However, for all but a handful of patients, cancer is able to develop resistance to targeted therapy over time.

A number of newer, more potent targeted therapies were developed in 2014 that further reduce side effects and help overcome resistance, at least for some time. Targeted therapy treatments have evolved and improved for patients with certain forms of lung cancer, leukemia, breast cancer and renal cell carcinoma.

Patients with cancer and their family members should be prepared to ask how specific the targeted treatment is for their own type of cancer (how well does it target their type of cancer cell), how long most people stay on the treatment, the benefits from the treatment, and what the side effects could be like. More...

Filed Under:

Promising Research

Making End-of-Life Plans

March 24, 2015

By Agnes Beasley, MSN, RN, OCN

A lot of us are planners. We plan work projects, celebrations, careers, family vacations, and retirements. However, the one area that most of us avoid thinking about, much less planning, is the end of our life. After all, we don't plan on having a terminal illness. We don't plan on dying any time soon. Decisions about end-of-life care are deeply personal, and are based on personal values and beliefs. No one wants to think about end-of-life issues when there are so many other happier activities to fill our calendars.

Still, at some point in time many of us will face making decisions about the dying process. How do you bring up the topic? When do you bring up the topic? Who do you talk to? Thinking about your end-of-life wishes, also known as advance care planning, can be hard and overwhelming. Most people expect their doctors to start the conversation about end-of-life planning - but only when it's necessary and not a moment sooner! That's especially true for people with cancer, especially when treatment may no longer be working. Many cancer patients and close family members may be thinking about discussing end-of-life issues with their doctor when the time comes, but where do they begin?  More...

Filed Under:

Caregiving | General

What keeps people from lifesaving colon cancer testing?

March 12, 2015

By Richard Wender, MD


We have made amazing progress in reducing colon cancer death rates. This progress is a direct result of increasing screening for colon cancer and pre-cancerous polyps. We are actually preventing thousands of cancers by finding and removing pre-cancerous polyps. The nation has embraced the goal of increasing national screening rates to 80% by the end of 2018 - an achievement that will substantially reduce the terrible toll that colon cancer exacts every year.  Everyone is at risk for colon cancer, whether or not someone in your family has ever had a colon polyp or colon cancer. For that reason, everyone has to start being screened for colon cancer at age 50, and people with inflammatory bowel disease or a family history of colon cancer or polyps have to start before they reach age 50. Colon cancer screening is one of the best opportunities to prevent cancer that we've ever discovered.

Despite this compelling reason to be screened, many people either have never had a colon cancer screening test or are not up-to-date with screening. Interestingly, nearly all of these unscreened people know that they should be screened, In fact, awareness about colon cancer screening recommendations approaches 100%. The American Cancer Society asked more than 2,000 unscreened adults a series of questions about screening, and we now have a pretty clear idea about what's stopping people from taking that lifesaving step:

  • Some people are concerned about the cost of the test
  • Others have heard that the test is difficult or painful, and they may be embarrassed to discuss colon cancer screening
  • Some people think screening is only for those who have symptoms
  • Others think that having no family history of colon cancer means that they are not at risk and don't have to be screened

Finally, and perhaps most importantly, many people are concerned about the complexity and cost of having a colonoscopy, like the need to take time off from work, the need to have a ride home, and the potential for high out-of-pocket expenses, which all combine to discourage them from having a colonoscopy. More...

Celebrating 25 Years of Smoke-Free Airplanes

February 25, 2015

By John R. Seffrin, PhD

Twenty-five years after a federal law passed banning smoking on all domestic flights, many of us don't even notice the lit "No Smoking" sign above our airplane seats. Until that landmark public health legislation took effect on February 25, 1990, flight attendants were subjected to deadly secondhand smoke during every flight and travelers who sat in "non-smoking" sections couldn't escape the fumes.

As a member of the American Cancer Society National Board of Directors 25 years ago, I agreed it was imperative for the Society to utilize its scientific expertise and passionate volunteer base to counteract the tobacco industry and protect non-smokers and flight attendants from the hazardous effects of secondhand smoke on every flight. We had the evidence to prove that smoke-free laws saved lives, so we decided to take the issue to Capitol Hill. The Society and its public health partners had champions in Senators Dick Durbin (D-IL) and Frank Lautenberg (D-NJ), whose unwavering support was instrumental in passing the legislation. (You can hear more about Senator Durbin's involvement in this video.)

The smoke-free airplanes legislation sparked a nationwide movement in support of smoke-free workplaces. In 2002, Delaware became the first state to enact a comprehensive smoke-free law covering all workplaces, including bars and restaurants. Since then, 23 other states and the District of Columbia have followed suit, and today nearly half of the U.S. population is protected by a comprehensive smoke-free law. 

The Society's advocacy affiliate, the American Cancer Society Cancer Action Network (ACS CAN), believes that the momentum that began 25 years ago cannot stall, especially with a tobacco industry that continues to use egregious tactics to addict kids to its deadly products. There are still 26 states lacking comprehensive smoke-free laws, 58 million Americans exposed to secondhand smoke and minority and low-income populations disproportionately subjected to the deadly impact of tobacco. It's hard to imagine that cigarettes were ever allowed on flights, and smoking in other workplaces, including restaurants and bars should become relegated to history books as well.

Tobacco will claim the lives of nearly half a million Americans this year. Evidence shows that enacting strong smoke-free laws that cover all workplaces, increasing tobacco excise taxes on a regular basis and fully funding tobacco prevention and cessation programs help people quit using tobacco and keep kids from ever starting. ACS CAN is working to make strong tobacco control laws a priority with elected officials at every level. From passing local smoke-free ordinances, to increasing the meager $1.01 federal cigarette tax, to funding tobacco education and cessation programs, to supporting strong federal regulation over the tobacco industry, ACS CAN is strengthening public policies in ways that help to change cultural views of tobacco use and will lead to a smoke-free, tobacco-free generation. 

 

Dr. Seffrin is the chief executive officer f the American Cancer Society and its advocacy affiliate the American Cancer Society Cancer Action Network.

Palliative care is part of good cancer care

February 16, 2015

By Diane E. Meier, M.D., FACP

Deborah, a 36-year-old mother of two young children, was diagnosed with breast cancer 2 years ago, and the disease has metastasized (spread) to her bones. The pain is severe, making it hard to care for her children or get to work.

Like any young mother, Deborah is determined to fight her cancer and be present for her son and daughter as they grow up. Deborah's oncologists, doctors at the top of their field, are intensely focused on controlling her cancer and identifying the chemotherapy plans that are most likely to work for her. But they have been unable to manage Deborah's pain. It had become so bad that she was unable to sleep or eat, spending much of the day curled on her side in bed. She missed a course of chemotherapy because of her pain, and she had to hire outside help to get her kids to and from school.

Deborah's long-time internist finally referred her to the palliative care team at her local hospital. They prescribed a low-dose opioid medicine and within 2 days, Deborah's pain was well controlled, she was up and around, sleeping and eating, and back to normal life with her family. She has been able to complete her latest course of chemotherapy and her oncologist feels her scans are showing a good response to the treatment.

Deborah's story is not unique. She is one of many thousands of people with cancer who have benefitted from palliative care, so that she can enjoy some normal day-to-day function and quality of life while she fights cancer. 

Palliative care for any stage of disease

 

Palliative care, sometimes called "supportive care," is medical treatment for people with serious illness. It's most often begun by the cancer care team, and referrals to or visits with palliative care specialists may happen later. Teams of palliative care specialists typically include doctors, nurses, social workers, and other healthcare professionals who work together with the patient, their family, and their other doctors to provide an added layer of support. The team works with the patient to provide relief from the pain and other symptoms, as well as the distress of their illness, so that the patient can live as well as possible. More...

Less Food Marketing, Healthier Children

January 20, 2015

By Colleen Doyle, MS, RD


Have you seen all those fun and flashy commercials encouraging your kids to eat more fruits and vegetables? No? Neither have I. And there's a reason for that. 

Out of the $1.79 billion that the Federal Trade Commission says major food and beverage companies spent marketing foods and beverages to kids and teens (in 2009 - the most recent data available), less than .05% was spent marketing fruits and vegetables. Unfortunately for those of us who care about children's health - which I hope is all of us - the majority of those dollars was spent on marketing unhealthy foods and beverages. Forty percent was spent to market fast food and other restaurant foods, and another 22% was spent promoting high-sugar sodas and other carbonated beverages.

And consider these additional statistics:

  • Two BILLION advertisements for foods and drinks appeared on websites directed at kids in 2009, mostly for sugary cereals and fast food.
  • Dollars spent to market foods and drinks to kids via online games, mobile apps, social network ads, and other digital media increased by 51% from 2006 to 2009.
  • Companies spent $149 MILLION in 2009 to market sugary drinks and food in schools.
  • Companies spent $113 MILLION in 2009 on packaging with marketing aimed at kids (think SpongeBob, Hello Kitty, and other characters).
  • Fast-food restaurants spent over $700 MILLION in 2009 on marketing to kids, nearly half of which was spent on kids' meal toys and giveaways.
  • Kids saw 12 to 16 TV advertisements per day for unhealthy foods or drinks in 2011.
  • Eighty-four percent of foods and drinks advertised to kids on Spanish-language television are unhealthy. More...

Chemo 101: What you need to know

January 12, 2015

By Agnes Beasley, MSN, RN, OCN

"What should I expect from chemotherapy?" 

I've heard those very words spoken by newly diagnosed cancer patients on many occasions in my extensive oncology nursing career. It's normal for a newly diagnosed patient to try to make sense of what is happening to them. Questions swirl like a tornado in a cancer patient's mind. You may feel that way right now. Some of the questions you may have are:

  • What can I expect on the day of chemotherapy (chemo)?
  • What can I expect when I go home after chemo?
  • What happens in the "chemo room?"
  • How long will it take to get my chemo?
  • Can I have someone with me during chemo to keep me company?
  • What am I allowed to bring with me to keep me busy?
  • Is it okay to sleep?
  • Will there be other people getting treatment around me or can I be in a private room?
  • I'm feeling anxious, overwhelmed, upset, and angry. Is what I'm feeling normal?
  • If I have questions, who do I call for the answers? More...

Filed Under:

Survivorship

The Cancer Atlas Reveals the International Burden of Cancer

December 03, 2014

By Ahmedin Jemal, DVM, PhD

The American Cancer Society has released the second edition of The Cancer Atlas book and, for the first time, a companion website. The Cancer Atlas provides in-depth information on the global burden of cancer, major risk factors, and cancer prevention and control measures.

Changes in developing countries leading to more cancer

 

It is estimated that the global burden of cancer is expected to rise from 14.1 million new cancer diagnoses in 2012 to 19.3 million in 2025 simply due to the aging and growth of the population. This is because the risk of getting cancer is greater as you age. During this period, even more cancers are diagnosed in less economically developed countries, increasing from 59% to 68% of the total cancer cases worldwide. In addition to aging, the burden is likely to increase as countries transition from a farming-based economy to an industry-based economy and as people change their work environments (office instead of farm), modes of transportation (driving instead of walking), and dietary habits (eating out instead of home cooked) - all of which lead to more obesity and physical inactivity, known risk factors for many common cancers.

Also, women are having fewer children and, therefore, also breastfeed for less time over the course of their lives, both of which may increase the risk of breast cancer. In addition, economically developing countries are being increasingly targeted by the tobacco, fast food, and beverage industries in search of new markets, leading to greater obesity, less physical activity, and more smokers. As a result, in many less developed countries more cancers such as lung, colorectal (colon), and breast are being diagnosed, and more people are dying from cancers typically associated with western lifestyles. In more developed countries, including the United States, rates of cancer diagnoses and deaths are decreasing or leveling off for the same cancers.  More...

Filed Under:

Global Cancer

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