Fighting breast, prostate cancers with dietary changes

• Written by Chukwuma Muanya with agency reports

• Eating high-fibre carbs, drinking less milk, others may help cut risk
• Infection makes men more vulnerable to disease
CALORIE restriction, a kind of dieting in which food intake is decreased by a certain percentage, has been touted as way to help people live longer.
          New research suggests that there may be other benefits, including improving outcomes for women in breast cancer. According to a study published May 26, 2014 in Breast Cancer Research and Treatment, the triple negative subtype of breast cancer – one of the most aggressive forms – is less likely to spread, or metastasize, to new sites in the body when mice were fed a restricted diet.
        “The diet turned on a epigenetic program that protected mice from metastatic disease,” says senior author Dr. Nicole Simone, an associate professor in the department of Radiation Oncology at Thomas Jefferson University. Indeed, when mouse models of triple negative cancer were fed 30 percent less than what they ate when given free access to food, the cancer cells decreased their production of microRNAs 17 and 20 (miR 17/20). Researchers have found that this group of miRs is often increased in triple negative cancers that metastasize.
      Breast cancer patients are often treated with hormonal therapy to block tumor growth, and steroids to counteract the side effects of chemotherapy. However, both treatments can cause a patient to have altered metabolism, which can lead to weight gain.
        In fact, women gain an average of 10 pounds in their first year of treatment. Recent studies have shown that too much weight makes standard treatments for breast cancer less effective, and those who gain weight during treatment have worse cancer outcomes. “That’s why it’s important to look at metabolism when treating women with cancer,” says Simone.
         Also, diet and lifestyle can play a role in lowering a man’s risk of prostate cancer, according to a trio of new studies.
        A diet rich in complex carbohydrates and lower in protein and fat is associated with a 60 percent to 70 percent reduced risk of prostate cancer, said Adriana Vidal, a co-author of two of the studies and an assistant professor at Duke University School of Medicine in Durham, North Carolina (N.C.), United States.
     In addition, a fiber-filled diet reduced the risk of aggressive prostate cancer by 70 percent to 80 percent, according to Vidal.
     “Good carbs, high-quality carbs, and high fiber are definitely protective against prostate cancer,” Vidal said.
          The two other studies found that:
*Drinking lots of milk could increase a man’s risk of advanced prostate cancer.
*Men suffering from two or more health problems linked to metabolic syndrome also have an increased risk of aggressive prostate cancer.
*Metabolic syndrome is a group of risk factors that increase a person’s risk of heart disease, diabetes and stroke.
         They include obesity, high blood pressure, elevated blood sugar levels, elevated levels of triglycerides (blood fats) and reduced levels of “good” High Density Lipo-protein (HDL) cholesterol.
         Also, scientists have said that prostate cancer could be a sexually transmitted disease caused by an infection passed on during intercourse.
         According to the study published in Proceedings of the National Academy of Sciences, researchers at the University of California discovered a sexually transmitted infection called trichomoniasis helps the growth of cancer cells in human prostate cells, when grown in a laboratory.
        But the team behind the discovery say more research is now needed to confirm the link.
        Researchers at the University of California have discovered that men infected with the sexually transmitted infection trichomoniasis are more susceptible to developing prostate cancer.
         And experts at Cancer Research United Kingdom (UK) told the BBC that more clinical studies are needed before the disease can be added to the list of cancers caused by Sexually Transmitted Infections (STIs).
            Trichomoniasis is the most common non-viral sexually transmitted infection, affecting around 275 million people across the world. Many people suffering the effects of the infection will have no symptoms.
 For those that do, they develop after around a month and for women cause soreness and itching around the vagina as well as a change in vaginal discharge.
Infected men may feel itching or irritation in the penis, pain during urination as well as a white discharge from the penis.
          In the new study, Professor Patricia Johnson found the parasite that causes trichomoniasis - Trichomonas vaginalis - secretes a protein that causes inflammation and increased growth and invasion of benign and cancerous prostate cells.
        Meanwhile, in earlier studies, Simone and colleagues had shown that calorie restriction boosted the tumor-killing effects of radiation therapy. This study aimed to examine which molecular pathways were involved in this cooperative effect.
       The investigators noticed that microRNAs – a type of RNA that regulates other genes in the cell – specifically miR 17 and 20, decreased the most when mice were treated with both radiation and calorie restriction. This decrease in turn increased the production of proteins involved in maintaining the extracellular matrix. “Calorie restriction promotes epigenetic changes in the breast tissue that keep the extracellular matrix strong,” says Simone. “A strong matrix creates a sort of cage around the tumor, making it more difficult for cancer cells to escape and spread to new sites in the body.”
    Understanding the link to miR 17 also gives researchers a molecular target for diagnosing cancers that are more likely to metastasize and, potentially, for developing a new drug to treat the cancers. In theory, a drug that decreased miR 17 could have the same effect on the extracellular matrix as calorie restriction. However, targeting a single molecular pathway, such as the miR17 is unlikely to be as effective as calorie restriction, says Dr. Simone. Triple negative breast cancers tend to be quite different genetically from patient to patient. If calorie restriction is as effective in women as it is in animal models, then it would likely change the expression patterns of a large set of genes, hitting multiple targets at once without toxicity.
      In order to test that this hypothesis is true in humans, Dr. Simone is currently enrolling patients in the CaReFOR (Calorie Restriction for Oncology Research) trial. As the first trial like it in the country, women undergoing radiation therapy for breast cancer receive nutritional counseling and are guided through their weight loss plan as they undergo their treatment for breast cancer.
“When men have two metabolic syndrome components, their risk of high-grade prostate cancer goes up almost 35 percent,” Vidal said. “With three to four components, their risk goes to almost 94 percent increased.”
       These studies shed more light on connections between diet, lifestyle and prostate cancer that up to now have been “tenuous,” said Dr. Durado Brooks, director of prostate and colorectal cancers for the American Cancer Society.
       “We don’t have as good evidence regarding a link between diet and prostate cancer as we do with colorectal cancer or breast cancer, and there has been some conflicting data in previous studies,” Brooks said.
      The first study focused on a group of 430 veterans at the VA Hospital in Durham, N.C., including 156 men with confirmed prostate cancer. Researchers had the men fill out questionnaires to track the amount of carbohydrates, protein and fat in their daily diets.
      The researchers found that when men received more of their energy from carbohydrates rather than protein or fat, their risk of prostate cancer declined. High fiber intake also appeared to reduce prostate cancer risk.
       Additionally, they found that foods like simple carbohydrates that cause blood sugar to spike appear to increase prostate cancer risk in black men.
       That finding, along with the results of the metabolic syndrome study, seem to indicate there could be an as-yet-unknown connection between blood sugar levels and male hormones like testosterone that increase prostate cancer risk, Vidal said.
       In the second study, doctors reviewed the consumption of dairy products among nearly 3,000 people, including almost 1,900 men with either localized or advanced prostate cancer.
       The investigators found that drinking milk was associated with advanced prostate cancer. However, total dairy consumption was not related to prostate cancer risk, nor were consumption of yogurt, ice cream and cheese.
      The analysis also found that men with low overall calcium intake were at greater risk of prostate cancer when they ate more dairy products, compared with men with average or high levels of calcium in their diet.
      The findings suggest that although calcium intake likely contributes to an increased risk of prostate cancer, “additional components in dairy may contribute to prostate cancer development,” the authors concluded.
     The final study focused on the effects of metabolic syndrome on a man’s chances of prostate cancer, with researchers reviewing data gathered for almost 6,500 men in an unrelated clinical trial.
       Researchers found that men with multiple metabolic syndrome risk factors had a progressively increased risk of prostate cancer. “The more metabolic syndrome components, the more risk for high-grade prostate cancer,” Vidal said.
      The findings are in keeping with previous studies linking one of those risk factors, obesity, to a higher risk of aggressive prostate cancer, Brooks said.
       “The question is whether because of their obesity these men are less likely to have their cancer identified and biopsied at an earlier stage,” he said. “These researchers feel there’s more than just delayed diagnosis, that there’s something about these risk factors that contributes to prostate cancer.”
         Findings from these studies were presented Tuesday at the American Urological Association’s annual meeting in Orlando, Fla. Results from studies presented at meetings are generally considered preliminary until they’ve been published in a peer-reviewed journal.
        A study carried out in 2006 at Washington University discovered men infected with trichomoniasis have a 40 per cent greater chance of developing prostate cancer. The STI is the most common non-viral sexually transmitted infection, affecting around 275million people across the world each year
         Scientists have been working to identify genes that may increase the risk of prostate cancer. In 2008, Cancer Research UK scientists discovered seven gene changes that increase a man’s risk of developing the disease.
       Some studies have found a link between an increased risk of prostate cancer in men who have had colon cancer.
       Siobhan Sutcliffe, who led the research, urged caution at the time, adding the link she found was ‘not conclusive’ comparing the science to the early connections drawn between smoking and lung cancer.
         Speaking at the time, she said: “It’s still in a really exploratory phase.”
A subsequent study found no connection between the STI and prostate cancer, while another at Havard University found an even greater likelihood of cancer in infected men than the 2006 study.
           Research in 2009 discovered a quarter of men with prostate cancer showed signs of having been infected with the STI, and were also found to have more advanced tumours.
       The new study, published in the journal Proceedings of the National Academy of Sciences, now suggests the infection might make men more vulnerable to developing prostate cancer, though does not provide proof of the link.
        The team has called for more research to build on their work, to work towards proving the link.