You might not be a smoker yourself, but hanging around people who are smoking can cause you to inhale noxious cigarette fumes. For years, scientists have cautioned against the ill-effects of such second-hand smoke. Now they’re warning about the dangers of “third-hand smoke”—the chemical traces that cling to a smoker, and that are left behind in a room where someone has been smoking.
A team of researchers at the Lawrence Berkeley National Laboratory found that remnants of a smoke don’t just inertly settle onto surfaces, they can react with a common gas (nitrous acid, which is emitted from gas appliances and vehicles, among other sources) to create carcinogenic compounds known as tobacco-specific nitrosamines (TSNAs) [Scientific American]. The study (pdf) was published in Proceedings of the National Academy of Sciences.
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The mysterious and deadly facial cancer that has sent populations of Tasmanian devils crashing now has a known source, according to findings published last week in the journal Science. The ailment originated in nerve cells of the devils themselves.
A genetic analysis of tumors from Tasmanian devils widely separated geographically shows that all the tumors are virtually identical and distinct from the animals’ own genomes…. The tumors probably arose from Schwann cells, which normally play a role in protecting and cushioning nerves [Los Angeles Times]. Tasmanian devils have a lot of nerves on their faces near their whiskers, the researchers note, and therefore have Schwann cells there. Team member Jenny Graves says the tumor could have arisen in one cell in one animal two decades ago, and then passed from devil to devil as they bit each other. The disease has already killed 60 percent of the population.
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The genomes of lung and skin cancer have been decoded by scientists at the UK-based Wellcome Trust Sanger Institute near Cambridge, which is the first time an entire cancer gene map has been created.
The scientists say they have pinpointed specific DNA errors that may cause tumors in these two cancers, both of which have direct known causes—smoking for lung cancer and sun exposure for skin cancer. Researchers predict these maps will offer patients a personalized treatment option that ranges from earlier detection to the types of medication used to treat cancer. The genetic maps will also allow cancer researchers to study cells with defective DNA and produce more powerful drugs to fight the errors, according to the the study’s scientists [CNN]. News reports are heralding the new research as revolutionary, however it will be years, perhaps decades, before the full implications of the work are understood.
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Are CT scans putting thousands of people in unnecessary jeopardy for cancers and death? That was the suggestion by two new studies out this week, leaving radiologists scrambling to explain the true level of danger to worried patients.
A CT scan, also known as computed tomography, gives doctors a view inside the body, often eliminating the need for exploratory surgery. But CT scans involve a much higher radiation dose than conventional X-rays. A chest CT scan exposes the patient to more than 100 times the radiation dose of a typical chest X-ray [Reuters]. However, a study out of the University of California, San Francisco says, we might not have as good a handle on CT radiation as we thought. The researchers found that radiation differed greatly between machines, and some emitted 13 times more than others.
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In the not too distant future, testing for certain cancers may be completed in less time than it takes to watch an episode of Scrubs. A new portable device, expected to be about the size of a paperback book, works by detecting biomarkers in the blood, substances that suggest that a patient is diseased. The sensor, which uses nanotechnology, is so accurate that it could pick up a grain of salt in a swimming pool, claim the researchers [Telegraph]. With just a small amount of blood and 20 minutes, doctors can have an electronic read out of biomarker concentrations at their fingertips. The research, led by Mark Reed at Yale University, may lead to quick, easy, and low-cost cancer tests.
Reed says the technology would be ideal for measuring lung cancer biomarkers in a phlegm sample, or colon or ovarian cancer biomarkers in a blood sample, making their technology the first to measure biomarkers from normal samples of bodily fluids. Previous technologies work in much the same way, but can only detect biomarkers in purified solutions, not the real thing — meaning fluid samples from patients [U.S. News and World Report]. The applications aren’t limited to cancer biomarker measurements; the researchers say they could also measure cardiovascular disease biomarkers in small blood samples. The scientists have published their research in the journal Nature Nanotechnology.
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Image: Mark Reed / Yale University
Last week DISCOVER brought you the sad and somewhat counter-intuitive study that suggested loneliness could actually be “contagious” and spread across a social network. Now more bad news for the lonely. In a study (in press) in the Proceedings of the National Academy of Sciences, another team of researchers argues that, in rats at least, loneliness can increase cancer incidence.
The scientists separated their test rats at birth, keeping them either in groups of five or alone. Those kept alone had a 135% increase in the number of mammary tumours, a 8,391% increase in the size of tumours and a 3.3-fold increase in the relative risk of malignancy [Nature News]. They also showed higher levels of the hormone corticosterone, which is connected to stress.
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One of the persistent fears of our modern era is that cell phone radiation may cause brain tumors. But here’s some good news: A team of researchers in northern Europe, however, has now combed through three decades of cancer registries and found no increase in the rate of brain tumors in the five to 10 years following widespread cell phone adoption in that region [Scientific American]. The researchers, from the Institute of Cancer Epidemiology in Copenhagen, studied 20 to 79 year old men and women from Denmark, Finland, Norway, and Sweden, and paid special attention to cancer rates during the cell phone boom of the mid-1990s. The researchers published their analysis in the Journal of the National Cancer Institute.
Overall the study found that cancer rates were unchanged from the period before mobile phones were widely used. The study was based on 59,684 brain tumour cases diagnosed over 30 years from 1974 to 2003 among 16 million adults. During this time, the incidence rate of cancers known as gliomas increased gradually by 0.5% per year among men and by 0.2% per year among women. For cancers known as meningioma, the incidence rate increased by 0.8% among men and, after the early 1990’s, by 3.8% among women [BBC News]. The researchers say the larger meningioma increase in women is due to the greater age of the women in this group.
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It started as an observation in a Seattle cancer ward, where oncologist Marc Chamberlain noticed that his male patients were often receiving steadfast support from their wives, while his female patients often didn’t have husbands hovering at their bedsides. Based on this anecdotal evidence, Chamberlain decided to investigate divorce rates among couples where one person had recently been diagnosed with a serious illness. His findings raise troubling questions about the loyalty of the male sex.
The study included diagnoses of both cancer and multiple sclerosis and found an overall divorce rate of nearly 12 percent, which is similar to that found in the normal population. But when the researchers looked at gender differences, they found the rate was nearly 21 percent when women were the patients compared with about 3 percent when men got the life-threatening diagnosis. The researchers suggest men are less able to commit, on the spot, to being caregivers to a sick partner, while women are better at assuming such home and family responsibilities [LiveScience]. However, the study did find that the divorce rate was lower in longer marriages.
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When 3-year-old Mark Blinder developed pain in his right arm, doctors diagnosed him with Ewing’s sarcoma, a rare bone tumor. Chemotherapy wasn’t working and radiation would have destroyed the growth plates in his bones. So instead of amputating the arm, doctors tried an experimental approach–implanting an artificial, expandable bone made of titanium and cobalt chrome, designed specifically for Mark. The bone, produced by the company Biomet Inc., is small enough to fit inside the 3-year-old’s arm, but should be sturdy enough to last his entire life. Most artificial bones are used to replace only part of a bone, so they are glued securely to remaining bone. In Mark’s case, the entire humerus was being removed, so the prosthetic had to be attached to soft tissue [Los Angeles Times].
To install the bone, doctors first had to remove the tumor by carving out the fat around it, a process one of the doctor’s likened to carving out a peach pit without ever touching the pit. The surgery was a success but Mark, who is now 4 years old, underwent chemotherapy as a precaution. Mark is gradually relearning how to use his arm. He’s moving his wrist and fingers, can pick up small objects, and is receiving physiotherapy to rebuild strength and flexibility in the elbow and shoulder. He won’t ever regain full function in those joints, but he is using the arm more each day, his mother said [Los Angeles Times]. He will have to undergo three or four minor surgeries over the years so doctors can extend the prosthetic bone as he grows–but since the only other option open to Mark was amputating his arm completely, he probably won’t complain.
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Cancer treatment in the future could have dramatically reduced side effects if new nanotechnology research proves useful. Heat-sensitive nanoparticles might be able to deliver drugs to a targeted location in the body—to a tumor, say—and release them on cue, a sought-after goal of biomedical research.
One research team has developed nanoparticle cages that can be stuffed with tiny amounts of drugs that are only released on demand. These “nanocages” are cubes of gold, with sides about 50-billionths of a meter long and holes at each corner. They are easily made, using silver particles as a mold, and then coated with strands of a smart polymer. The polymer strands are normally extended and bushy and cover the holes in the cube. But when heated the strands collapse, leaving the holes open and allowing the drug inside to escape [The New York Times]. The researchers say they can engineer the nanocages to stick to tumors.
Doctors could release the packaged drugs whenever they want, just by zapping the cages inside the patient’s body with near-infrared light. Near-infrared wavelengths are not greatly absorbed by body tissues, so light from a near-infrared laser could penetrate a couple of inches inside the body, but they are absorbed by gold [The New York Times]. Researchers could design the cages to fall apart at just a few degrees above normal body temperature, so they only spill their contents where the heat is applied; they could also alter the drug’s rate of release by adjusting the laser’s intensity. The technology, described in the journal Nature Materials, could help cut down on the side effects of today’s treatments which are often caused by toxic drugs coursing through the body.
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Image: Younan Xia, Washington University in St. Louis
The naked mole rat is a species with a long list of peculiarities. The mole rat is about the same size as the more hirsute wild mouse, but lives seven times as long, sometimes reaching the ripe old age of 28. The creatures almost never poke their noses beyond the snug confines of their burrows and tunnels, and instead live out their lives underground in the dark. They’re also the only mammals who have a social structure that resembles an ants’ nest or beehive, where only one dominant female mates and reproduces.
Finally–and this is the part that most interests researchers–naked mole rats never get cancer.
A new study in the Proceedings of the National Academy of Sciences probed the mole rats’ robust good health, and determined how they beat cancer. The naked mole rat’s cells hate to be crowded, it turns out, so they stop growing before they can form tumors…. Normal human and mouse cells will grow and divide in a petri dish until they mash tightly against one another in a single, dense layer–a mechanism known as “contact inhibition.” Naked mole rat cells are even more sensitive to their neighbors, the researchers found. The cells stop growing as soon as they touch [ScienceNOW Daily News]. Researchers hope that the mechanism can one day lead to novel treatments for cancer, where cancerous cells won’t stop multiplying and form tumors.
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For all those patients who shudder at the thought of getting a colonoscopy and stubbornly refuse to make that appointment, there may soon be an alternative. Italian researchers have invented a “spider pill” that can be swallowed like a normal pill, but which later crawls through the intestines to check for signs of colon cancer. The researchers say the spider pill could be a great advance, because while the long and flexible endoscopes typically used in colonoscopies are very effective, many people balk at having a tube run through them.
The tiny bot contains a camera so doctors can monitor its progress through the digestive system (as demonstrated in this video). Once it hits the colon, doctors use a wireless link to command it to unfold its eight legs, and then order it to and fro so they can carefully check for polyps or tumors. Pills containing cameras already exist, but this is believed to be the first that can be controlled after it has been swallowed. Once the examination has finished, the spider pill exits the body naturally [Telegraph]. So far, the device has only been tested on pigs.
The researchers also invented a related device to survey the stomach, which contains more liquid than the intestines. That little bot uses propellers instead of legs to get around.
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In very rare cases, the womb is a dangerous place for a developing fetus. Researchers have found that pregnant women can pass on cancer cells to their unborn babies, if those cancer cells carry a particular genetic mutation. The new study resolves a longstanding puzzle, because in theory any cancer cells that manage to cross the placenta into the baby’s bloodstream should be targeted for destruction by the child’s immune system. But there are records of 17 cases of a mother and baby appearing to share the same cancer – usually leukaemia or melanoma [BBC News].
In the study, which will be published in Proceedings of the National Academy of Sciences, researchers used a genetic “fingerprinting” technique to match the cancer cells found in a mother and baby. The case, involving a Japanese mother aged 28 and her daughter, revealed that both patients’ leukaemic cells carried the identical mutated cancer gene BCR-ABL1 even though the infant had not inherited this gene [The Times]. This meant that the child, who was diagnosed with cancer at the age of 11 months, could not have developed leukemia independently.
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The Nobel Prize for medicine has been awarded to three U.S. researchers who probed the mechanism of cellular division, and whose work opened new avenues both in the fight against cancer and attempts to slow aging. The prize will be shared by Australia-born Elizabeth Blackburn, Carol Greider, and London-born Jack Szostak.
The three researchers solved the mystery of how chromosomes, the rod-like structures that carry DNA, protect themselves from degrading when cells divide. The Nobel citation said the laureates found the solution in the ends of the chromosomes — features called telomeres that are often compared to the plastic tips at the end of shoe laces that keep those laces from unraveling [AP].
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The first scientific autopsy on an ancient Egyptian mummy, performed back in 1825, might have botched the cause of death. The original ruling was that the mummified woman, Irtyersenu, died of ovarian cancer, but a new study strongly suggests she died of tuberculosis [BBC News]. The original autopsy was performed by one Dr. Augustus Bozzi Granville, a surgeon and a gynecologist (and apparently a fan of infectious diseases; he personally overcame bouts with malaria, bubonic plague and yellow fever).
Irtyersenu is a remarkable specimen in that she was mummified with her organs intact. Most mummies have their organs removed or dissolved inside their bodies prior to mummification. Dr. Granville was correct in detecting that the mummified woman had an ovarian tumor—but later studies determined it was benign. Granville studied her pelvic bone and also determined the woman to be an overweight mother between the ages of 50-55 when she died.
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