It’s possible that the most severe forms of prostate cancer are caused by a virus that might be sexually transmitted, according to a new study that will be published in the Proceedings of the National Academy of Sciences this week. Researchers checked for the virus in more than 200 prostate cancer patients and found the virus in 27 percent of the men; those with the most aggressive tumors were most likely to have the virus. While the researchers haven’t proved causation, they note that viruses are known to cause a variety of human cancers. Hepatitis viruses, for example, cause liver cancer, while human papilloma virus causes cervical cancer in women and anal and penile cancer in men [Los Angeles Times].
The virus, known as XMRV, belongs to a family of viruses that has previously been shown to cause leukemia in lab animals. Like the HIV virus, XMRV is a retrovirus, a virus that gets incorporated into the genome of the cells it infects. It may trigger cancer by locating in the cell’s genome next to DNA that controls cell growth, and disrupting those genes in a way that allows cells to replicate uncontrollably [Bloomberg].
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In a doctor’s office in the near future, part of a smoker’s routine checkup could involve blowing into a tube connected to a small sensor. The doctor will look at the sensor’s display and know immediately whether she has to deliver the grim diagnosis: lung cancer. Researchers in Israel have invented a new “breathalyzer” that can detect chemical compounds produced by lung cancer cells. The finished device should be portable and inexpensive and provide a faster, easier, and more sensitive way to screen for tumours than X-rays or blood tests. Such screening should help doctors detect cancer early, when it’s most treatable [Telegraph].
The new device, described in Nature Nanotechnology, is not the first to find evidence of cancer on a person’s breath. Other attempts to do this have yielded promising results, … but those devices require a higher concentration of the telltale biomarker chemicals than the Israeli device. The chemicals, called volatile organic compounds (VOCs), are metabolic products present in the vapors that we breathe out, but they occur in such small amounts that researchers have had to find ways to increase their concentrations before testing [Technology Review]. But the new sensor has such sensitivity that it can detect traces of the compound in their natural concentrations in human breath, and it can therefore give results immediately, without processing and analyzing the sample in a lab.
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Medical imaging tests such as CT scans are valuable diagnostic tools, but their increasing use in doctors’ offices and hospitals is providing a sizable dose of radiation for about 4 million Americans under the age of 65. About 400,000 of those Americans receive very high doses, more than the maximum annual exposure allowed for nuclear power plant employees or anyone else who works with radioactive material [The New York Times], according to a study published in The New England Journal of Medicine.
Researchers based their estimates on a study of almost 1 million people between the ages of 18 and 64 who they followed for almost three years, and found that nearly 70 percent of test subjects were subjected to at least one procedure that would have exposed them to radiation. Although the study didn’t examine whether this radiation could cause an increase in cancer rates, some experts believe it would probably result in tens of thousands of additional cancers…. Each individual patient is at relatively minor additional risk from the tests, [researcher and cardiologist Rita] Redberg said, but because they are given to so many people, the cumulative risk is significant [The New York Times].
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Image: iStockPhoto
Saving Tasmanian devils from the infectious cancer that has quickly rendered the small marsupials an endangered species will be an even harder than we realized, according to a new study. The latest bad news from Tasmania: Researchers have found that devils are not solitary creatures with small social networks, but instead frequently interact with other devils, allowing for faster spread of the disease. The devastating cancer, known as devil facial tumor disease, is spread by biting, something the aggressive animals apparently do a lot of.
Investigating the social behaviour of devils, which are nocturnal, forest-dwelling and mate underground is tricky [ABC Science], notes lead researcher Rodrigo Hamede. To get around this difficulty, Hamede outfitted 46 wild devils in a disease-free area with radio collars that recorded every time one devil approached within 12 inches of another–close enough to bite. The scientists found that all 27 of the devils from which intact collars were recovered belong to a single large social group. Each animal is connected to all the others, either directly or through connections with other animals. The finding suggests that if any one of the animals becomes infected with the facial tumor disease, the cancer would spread to the entire network [Science News].
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Breast-feeding may significantly cut a woman’s risk of breast cancer if she has an immediate relative that has ever had the disease, according to a study published in the journal Archives of Internal Medicine.
Among women with close family members who have had breast cancer, the risk of developing the disease before menopause sank by 59 percent if she ever breast-fed, according to the research, which used data from more than 60,000 subjects of the Harvard Nurses’ Health Study. The risk of breast cancer in women without the disease in the family was unaffected by breast-feeding. The findings suggest that breast-feeding may prove just as effective a strategy for high-risk women as the use of Tamoxifen, a drug that interferes with estrogen activity and is often used in high-risk women to reduce breast cancer risk [The New York Times]. For women with a high risk of breast cancer, due to factors like a family history of the disease or a genetic predisposition to develop it, the only preventive measures currently used are Tamoxifen and the prophylactic removal of the breasts.
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An international health agency has officially ruled that tanning beds pose as likely to cause cancer as cigarettes, asbestos, and arsenic. The International Agency for Research on Cancer (IARC) moved ultraviolet-emitting tanning beds from the category of “probably carcinogenic” to definitely “carcinogenic to humans.”
The IARC is an expert committee that makes recommendations to the World Health Organization. It made its decision following a review of research which concluded that the risk of melanoma – the most deadly form of skin cancer – was increased by 75% in people who started using sunbeds regularly before the age of 30. In addition, several studies have linked sunbed use to a raised risk of melanoma of the eye [BBC News]. The study results and the new classification were published in the journal Lancet Oncology, and experts say the findings are likely to prompt calls for stricter regulations of tanning salons.
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Chemotherapy destroys cancer cells, but it also kills healthy cells. In addition, cancer cells left behind after treatment can develop resistance to therapy, rendering follow-up treatment ineffective. But a new type of cancer treatment that uses cellular “Trojan horses” to slip into cancer cells could remedy that. In a study published in Nature Biotechnology, Australian researchers describe a method that has successfully treated aggressive and resistant tumors in mice and dogs.
The technique uses a rising technology known as RNA interference, or RNAi, which was the subject of research for the 2006 Nobel Prize in medicine recipients. This technology prevents the cell from manufacturing proteins by muting the genes responsible for their production, and relies on “mini-cells” to silence these genes. In the new study, these mini-cells were produced by bacteria and then coated with antibodies the cancer cells recognized, which allowed the mini-cells to target and slip inside of cancer cells like a Trojan horse.
The researchers use a two-step attack against the cancer cells. The first wave of mini-cells releases molecules that switch off the production of proteins that make the cancer cell resistant to chemotherapy. A second wave of EDV [mini] cells is then accepted by the cancer cell and releases chemotherapy drugs, killing the cancer cell. “The beauty is that our EDVs operate like ‘Trojan Horses’ They arrive at the gates of the affected cells and are always allowed in” [Reuters], says study coauthor Jennifer MacDiarmid.
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Apple chief executive and all-around tech visionary Steve Jobs reportedly received a liver transplant two months ago in Tennessee, and is on track to return to work by the end of the month. Jobs presumably underwent the procedure to treat a reappearance of the cancer he was diagnosed with several years ago. In 2004 Jobs had surgery to remove a rare, slow-growing type of pancreatic cancer, called a islet cell neuroendocrine tumor, but he was thought to be in remission until last year, when a period of drastic weight loss last year led to frenzied speculation that the cancer had returned [The Guardian].
Jobs’s health has been a matter of intense interest to Apple investors, who feel that his leadership is key to the company’s continuing success, and questions have been raised about the company’s handling of the matter. In January, the notoriously secretive Jobs made a rare public statement attributing his weight loss to a “hormone imbalance”. Just a few days later, however, he was forced to admit that the situation was “more complex” than first thought, before announcing his intention to step down from day to day activities at Apple for six months [The Guardian].
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Scientists have taken another step in cellular reprogramming that points the way towards the use of a patient’s own cells to treat genetic diseases. In a proof of concept study, researchers took skin cells from patients with a rare condition, Fanconi anemia, which causes skeletal problems and bone-marrow failure, and raises sufferers’ risk of cancer [Technology Review]. In the skin cells, the researchers fixed the genetic defects that caused the disease, and then reprogrammed the cells to act like stem cells capable of growing into any type of tissue.
The corrected stem cells could be grown into blood precursor cells for therapy. As these would carry a patient’s own DNA, except for the mutation responsible for the illness, they could be transplanted without risk of rejection by the body’s immune system [Times Online]. However, the patched up cells were not used to treat patients in this study, because it isn’t yet clear whether such cells are safe. Comments molecular geneticist Chris Mathew: “In future it may become possible to transfer the corrected stem cells back into the patient, but much work remains to be done before this can be transferred from the lab bench to the bedside” [The Scientist].
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What if we stopped trying to cure cancer, and learned how to live with it? That’s the provocative question asked by mathematical oncologist Robert Gatenby in an essay published in Nature (subscription required). Gatenby argues that by trying to eradicate tumors with heavy doses of chemotherapy, doctors sometimes end up selecting for drug-resistant cancer cells that can spread rapidly once treatment is halted. Instead, he suggests giving patients moderate doses that aim to stabilize the tumor and prevent its growth.
If doctors were guided by this principle, it would change treatment fundamentally, Gatenby says. “Your whole goal is to keep the tumor stable…. With a mouse ovarian cancer model, if you treat it with a very high dose, the tumor goes away. It looks like you’ve cured it. But a couple weeks later it comes back and starts killing animals. This is a standard outcome. What we did is use smaller doses of drugs and applied them when necessary. We were able to keep tumors stable and mice alive indefinitely” [Wired], he says.
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Tumors may physically trigger depression by producing chemicals that induce negative mood swings, according to a new study. The research, conducted in rats, allowed for the isolation of “just the physiological effects of the tumors from the psychological effects…. The tumors themselves are sufficient to induce depression” [The Scientist], says lead researcher Leah Pyter.
The new study, published in the Proceedings of the National Academy of Sciences, showed first that rats who had cancer exhibited several behavioral symptoms associated with depression. The researchers gave a forced swimming test to 100 rats, some healthy and some with cancer, and found that the sick rats did not try as hard to escape—a behavior similar to that seen in humans with depression. The sick rats were also less interested in sugar water, which is the the clear preference for healthy rats.
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A major new lawsuit is challenging the notion that human genes can be patented just like the latest mousetrap built by a basement inventor. The case focuses on two genes, BRCA1 and BRCA2, that are linked to a higher risk of breast and ovarian cancer, and which were patented by the company Myriad Genetics more than 10 years ago. Now, the ACLU has organized a lawsuit backed by organizations representing more than 100,000 doctors and geneticists, and will argue that the information contained in each person’s DNA should not be private property.
The plantiffs also include individual cancer patients like Genae Girard, who was diagnosed with breast cancer, and took Myriad’s genetic test to see if her genes also put her at increased risk for ovarian cancer, which might require the removal of her ovaries. The test came back positive, so she wanted a second opinion from another test. But there can be no second opinion [The New York Times]. Since Myriad owns the patent to both the two genes and the test that looks for them, no other company can develop a competing test.
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The beating of the heart inside an embryo doesn’t just circulate blood through the developing creature, it also triggers the formation of blood stem cells, the cells that give rise to all other forms of blood cells, according to two new studies. The surprising findings show that the physical force of the heartbeat and blood flowing through the aorta cause embryonic stem cells to differentiate–although researchers don’t yet understand quite how this is accomplished.
The findings could eventually have practical applications for people with blood cancers and other diseases that are treated with transplants of bone marrow, the site of blood stem cell production. Scientists can make red and white blood cells easily in the laboratory, but bone marrow patients need blood stem cells to constantly replenish their blood supply. Producing these cells, also called hematopoietic stem cells, is much more difficult…. Only about a third of patients who require bone marrow transplants have matching donors. “Basically we cannot offer optimal therapy to two-thirds of patients” [Science News], says Leonard Zon, coauthor of one of the new studies. If researchers can learn how the body stimulates blood stem cell production, they may be able to duplicate the process in the lab, says Zon.
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In recent years, antioxidants have been touted as a secret to healthy living: The molecules bind to reactive oxygen compounds called “free radicals” that are known to damage the body’s tissues. The amount of oxidative damage increases with age, and according to one theory of aging it is a major cause of the body’s decline [The New York Times]. But a new study examined the effects of the antioxidant vitamins C and E when combined with an exercise regimen, and found a considerably more complicated story. The researchers found that free radicals may be beneficial in small doses, and may even help protect against diabetes. And mopping them up with antioxidants may do more harm than good [BBC News].
During a workout, the muscles metabolize glucose to create energy, but in the process some free radicals are released. The body has a natural defense mechanism to combat these free radicals, but many researchers had theorized that the body can’t catch all of the harmful compounds, which makes antioxidant supplements sound like a logical solution.
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Cardiologist and author John Sotos has a theory about why Abraham Lincoln was so tall, why he appeared to have lumps on his lips and even why he had gastrointestinal problems. The 16th president, he contends, had a rare genetic disorder — one that would likely have left him dead of cancer within a year had he not been assassinated [Time]. But for Sotos to prove his case, he needs a snip from a historical relic: a piece of the bloodstained pillowcase on which the dying Lincoln rested his head after he was shot at Ford’s Theater on April 14, 1865.
The piece of cloth is displayed under glass at the Grand Army of the Republic Civil War Museum and Library in Philadelphia. Sotos has asked the museum’s board for a sample of the pillowcase, which is stained with both blood and brain matter. But the board is fiercely debating whether to concede to his request. “This is the Shroud of Turin of Civil War history,” said Andy Waskie, a board member…. “We are guardians in trusteeship of this extraordinarily important artifact. On the basis of pure science, the testing is of interest. We have not eliminated it as an option . . . but we want more information” [The Philadelphia Inquirer].
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