Circumcision reduces a man’s risk of HIV infection, scientists have said, although they didn’t exactly understand the “why” behind the link. Now researchers think they know.
It comes down to microbes. Specifically, removing the foreskin leads to a dramatic reduction in overall bacteria, including anaerobic bacteria, on the penis. Such bacteria can prevent so-called Langerhans cells in the foreskin from fighting off viruses, also leading to inflammation that prompts the body’s immune system to send T4 cells to the scene. These cells can then become infected with HIV.
The findings, published April 16 in the journal mBio, amount to an “aha” moment.
“The bacterial changes identified in this study may play an important role in the HIV risk reduction conferred by male circumcision. Decreasing the load of specific anaerobes could reduce HIV target cell recruitment to the foreskin,” the authors wrote.
Their research on the so-called penis microbiome has led the researchers to make broader ecological comparisons.
“From an ecological perspective, it’s like rolling back a rock and seeing the ecosystem change. You remove the foreskin and you’re increasing the amount of oxygen, decreasing the moisture – we’re changing the ecosystem,” said corresponding author Lance Price in a press release from the American Society of for Microbiology, which publishes mBio.
The study’s first author, pathologist Cindy Liu at Translational Genomics Research Institute in Flagstaff, Ariz., summed up her findings this way to the L.A. Times: “It’s the same as if you clear-cut a forest. … The community of animals that once lived in that forest is going to change.”
As for clinicians, they appear to welcome the findings.
Alexandra Levine, M.D. M.A.C.P., chief medical officer at City of Hope, said the study’s authors make a strong case. “This is an important paper in beginning to document what the reason might be,” Levine, a nationally recognized expert on blood diseases and HIV/AIDS-related malignancies, told the L.A. Times. ”Their data are convincing to me.”
But scientific discovery doesn’t stop with an “aha” moment. As the authors themselves noted in their paper, more research is needed.
“Understanding the mechanisms that underlie the benefits of male circumcision could help to identify new intervention strategies for decreasing HIV transmission, applicable to populations with high HIV prevalence where male circumcision is culturally less acceptable.”
Cancer knows no boundaries: It affects men and women, the young and the old, the rich and the poor, and people from all ethnic backgrounds. But, in the U.S., cancer has a disproportionate impact on minorities.
Among men, the rate of new cancer cases – and death rates – are highest among black men, says the federal Centers for Disease Control and Prevention. Among women, although the rate of new cancer cases is highest among white women, death rates are higher among black women.
Although Hispanics have lower incidence rates for all cancers, combined, when compared to whites, they have higher rates of cancers linked to infections, such as uterine, cervix, liver, gallbladder and stomach cancers, says the American Cancer Society in providing an overview by ethnic group. Further, breast cancer is generally diagnosed in Hispanic women at a later age than in other groups.
Such cancer disparities can be attributed to a combination of factors: a lack of early detection, insufficient attention to healthy lifestyles and poor access to health care. But each factor must be targeted to eliminate inequalities in cancer outcomes.
These disparities are likely to get widespread attention this week, designated as National Minority Cancer Awareness Week, but they’re the focus of Kimlin Tam Ashing-Giwa, Ph.D., every day. Continue reading “Minority Cancer Awareness Week: End disparities now” »
People with a family history of breast cancer often seek genetic testing to find out whether they carry mutations to key genes called BRCA1 and BRCA2, greatly increasing their risk for breast cancer and other diseases.
For this small but significant portion of the population, knowledge is power. They have seen their grandmothers, aunts, cousins and sisters struggle with breast or ovarian cancer. They may have faced these diseases themselves.
Discovering the details about their own genetic predisposition allows them to make informed choices about prevention options ranging from frequent screening to preventive surgery. It enables them to pass on the warning to other family members to get tested themselves.
However, misconceptions about how these mutations are passed down — and about what the tests themselves mean — can get in the way of sound decision-making.
Cancer risk counselor Kathleen Blazer, Ed.D., M.S., L.C.G.C., assistant professor in City of Hope’s Division of Clinical Cancer Genetics, trains other health-care professionals to provide genetic screening.
“Making sure that doctors, counselors and scientists truly understand cancer genetics is important,” Blazer said. “That’s why we provide face-to-face and online instruction on the latest in the field.”
In a recent interview, she helped clear the air about a few common myths concerning BRCA1 and BRCA2, the “celebrity genes” of hereditary breast and ovarian cancer risk.
For nearly two decades, researchers have theorized that physical activity helps prevent breast cancer – particularly in older women – by lowering their estrogen levels.
Now, a new study offers clues into how exercise may provide this protection.
The preliminary findings were presented April 9 at the American Academy of Cancer Research (AACR) meeting in Washington, D.C., by Cher Dallal, Ph.D., a National Cancer Institute prevention fellow.
Researchers evaluated the influence of physical activity on the breakdown of estrogens in postmenopausal women. Known as estrogen metabolism, this process produces molecules called metabolites that break down the estrogen.
Researchers studied the cases of 540 healthy, postmenopausal women between the ages of 40 and 74 who were enrolled as control patients in the National Cancer Institute Polish Breast Cancer Study from 2000-2003. None of the women took hormone therapy.
For seven days, study participants wore small devices called “accelerometers” around their waists while they were awake to record their varying degrees of physical activity. The devices are believed to be a more accurate accounting of physical activity than subjects’ memories. The women also collected samples of their urine during a 12-hour period.
Researchers tested the urine for estradiol and estrone, two “parent” estrogens, as well as 13 different metabolites.
“This is the first study to consider the relationship between accelerometer-measured activity and a panel of estrogen metabolites measured in urine,” said Dallal in an AACR press release. “We hoped by using direct measures to examine this relationship that we could improve our knowledge of how these factors may influence cancer risk among postmenopausal women.”
“By using these new tools to study the relationship between activity and estrogen metabolism, we hope to get closer to uncovering the combination of parent estrogens, metabolites and metabolism pathways that are related to a lower-risk profile of breast cancer,” Dallal continued.
One of the first scientists to make the connection between physical activity and breast cancer risk was Leslie Bernstein, Ph.D., professor and director of the Division of Cancer Etiology at City of Hope.
“We know for breast cancer [risk], hormones are important,” Bernstein told Healthday.
“This is the first time we have strong evidence that measured physical activity reduces hormone levels. It helps us understand what’s going on and how it’s working.”
She lauded the study’s use of the accelerometer, which provides a more objective measure than asking women to recall how much energy they expended.
Bernstein has long championed exercise’s ability to lower estrogen exposure and breast cancer risk, not to mention insulin levels and weight. Women often gain weight after menopause, and estrogen lurks in fat tissue, increasing women’s risk of breast cancer.
As researchers continue to explore exercise’s potential benefits – such as whether physical activity can actually repair DNA – Bernstein urges women to get a move on.
Women who have been estranged from exercise for awhile, she said, should first obtain their doctor’s blessing, then begin physical activities like brisk walking that “puts some stress on the body.”
Although childhood cancers only make up 2 percent of all cancers, they are also among the most treatable. According to the American Society of Clinical Oncology, the overall survival rate of childhood cancer is more than 80 percent.
However, being diagnosed with and treated for cancer in childhood creates a new set of problems: chronic, late effects that can affect patients’ health and well-being throughout their adult years, long after they’re considered “cured” of cancer. As the population of childhood cancer survivors grows, clinicians are paying increasing attention to this problem.
“In the last few years, survivorship has become an extremely important issue,” said Karla Wilson, M.S.N., R.N., nurse practitioner in City of Hope’s Childhood Cancer Survivorship Program. “It is crucial to evaluate patients for late effects of treatment, and inform them of their late-effects risks specific to their diagnosis and treatment so they can take proactive steps to minimize those risks.”
To help get the word out about learning and managing these risks, Wilson and other experts will participate in the upcoming session “Ask the Experts: Childhood Cancer Survivors: Taking Charge of Your Health,” moderated by Smita Bhatia, M.D., M.P.H., Ruth Ziegler Chair in Population Sciences.
Some of these issues include: Continue reading “Ask the Experts: Helping children thrive after cancer” »
Numerous studies have connected the dots between alcohol consumption and breast cancer, but the impact on breast cancer survival has been less clear.
A new study suggests not only that breast cancer survivors can continue to drink alcohol in moderation, without fear of endangering their survival, but that moderate imbibing might produce an added survival benefit – a reduced risk of dying from cardiovascular disease. Because of the toxicity of some cancer treatments, heart disease is a major cause of mortality among breast cancer survivors.
“Women consuming moderate levels of alcohol, either before or after diagnosis, experienced better cardiovascular and overall survival than nondrinkers,” wrote principal investigator Polly A. Newcomb, Ph.D., a member of the Public Health Sciences Division and head of the Cancer Prevention Program at Fred Hutchinson Cancer Research Center.
The findings were published April 8 in the Journal of Clinical Oncology.
An estimated 65 percent of women in the United States consume alcohol, and drinking is widely recognized as a breast-cancer risk. But researchers sought to examine the relationship between pre- and post-diagnosis drinking and mortality among breast cancer survivors.
Most cancer immunotherapies are designed to take a patient’s own T cells, a type of white blood cell, and genetically engineer them to target, and destroy, cancer cells. But T cells are only one part of the immune response, and eliciting an effective response from an immune system already weakened by cancer can be difficult – especially in leukemia, in which defective white blood cells are the problem.
City of Hope researchers may have found a way around this hurdle.
They’ve developed a gene therapy that both stimulates an immune response against cancer cells and uses short-interfering RNA to shut off the STAT3 gene, which is crucial in helping many cancers grow. Shutting down this gene enhances the immune system’s response against the cancer cells and discourages growth of the tumor.
Marcin Kortylewski, Ph.D., assistant professor in City of Hope’s Department of Cancer Immunotherapeutics and Tumor Immunology, recently led an investigation of the new gene therapy, known as CpG-STAT3 siRNA, in treating acute myeloid leukemia. Results from his study in mice were presented today at the annual meeting of the American Association for Cancer Research in Washington, D.C.
Continue reading “Immunotherapy enlists more than just T cells to treat leukemia” »
Small cell lung cancer is an aggressive type of cancer that readily metastasizes to other organs in the body. The disease can be tough to treat, because the cancer cells often develop resistance to the drugs commonly used against them.
Now City of Hope researchers may have found a way to overcome this drug resistance – by using an extract of the milk thistle plant. The plant has long been used as a natural supplement for various conditions, and the latest research opens the door on a powerful new use. Findings from the researchers’ laboratory study were presented today at the annual meeting of the American Association for Cancer Research in Washington, D.C.
Susan Kane, Ph.D., a professor in City of Hope’s Department of Cancer Biology, and David Sadava, Ph.D., a visiting professor from the Claremont Colleges, compared effects of the extract silibinin on two specific cancer cell lines that have shown resistance to three common chemotherapeutics – etoposide, doxorubicin and vincristine.
Continue reading “Milk thistle extract could help defeat small cell lung cancer” »