WEDNESDAY, April 2 (HealthDay News) -- Stanford University researchers have developed a new imaging system that illuminates tumors deep inside the body and lets doctors view details 1,000 times smaller than previously possible.

Raman spectroscopy uses tiny nanoparticles injected into the body to serve as beacons for lasers, according to a description the method published in this week's online issue of the Proceedings of the National Academy of Sciences.

When a laser beam outside the body hits them, the specialized particles emit signals that can be converted into a visible indicator of their location in the body. These strong, long-lived signals can simultaneously transmit information about multiple molecular targets.

"Usually we can measure one or two things at a time," senior author Dr. Sanjiv Sam Gambhir, a professor of radiology at Stanford's School of Medicine, said in a prepared statement. "With this, we can now likely see 10, 20, 30 things at once."

The new system utilizes the Raman effect, which occurs when light is shined on an object. The light causes roughly one in 10 million photons to bounce off the object's molecules with an increase or decrease in energy, called Raman scattering. This forms a unique measurable pattern, called a spectral fingerprint, for each type of molecule.

The Stanford research team tested the system on mice, injecting them with various engineered Raman nanoparticles and then viewing the anesthetized mice under a special microscope where they were exposed to laser light. The nanoparticles, for example, would be "tagged" with different pieces of proteins that sought out different tumor molecules.

In these experiments, the team spotted targets 1,000 times smaller than what is viewable with the most precise fluorescence imaging available. Since the Raman effect lasts indefinitely, as long as the particles stay in the body they can work as signals.

Because of these findings, the technique could be useful during tumor surgery on humans by aiding in the removal of even the most microscopic bits of cancerous tissue, the researchers said.

Gambhir's lab is further studying these Raman nanoparticles, including optimizing their size and dosage and evaluating possible toxicity. A clinical trial using gold nanoparticles in humans in conjunction with a colonoscopy to indicate early-stage colorectal cancer is being planned.

More information

The U.S. National Library of Medicine and the National Institutes of Health has more about diagnostic imaging techniques.

WEDNESDAY, April 2 (HealthDay News) -- Scientists have pinpointed an area on chromosome 15 that has three nicotine receptor genes that appear to increase the risk for lung cancer.

This finding offers yet more evidence that lung cancer is tied to genetics and not just smoking. However, whether these gene variants represent a direct risk for lung cancer and increased susceptibility to smoking isn't clear, according to two studies published in the April 3 edition of Nature and one published in the April 2 online edition of Nature Genetics.

In the first study, researchers show a link between gene variants that increase one's affinity for smoking and the risk for lung cancer.

"We started by looking at the impact of gene variants on smoking behavior," Dr. Kari Stefansson, president of deCODE Genetics Inc., said during a Tuesday teleconference on the research.

In the study, Stefansson, looked at 14,000 smokers and found nicotine receptor genes that affect how much one smokes. These genes appear to influence the quantity of smoking as well as smoking dependence.

"In addition, we found a gene variant which confers nicotine dependence also confers a fairly substantial risk of lung cancer and peripheral arterial disease," Stefansson said. "So people who have inherited this variant from one parent have a 30 percent greater risk of developing lung cancer."

This variant is common in about 40 percent of the population, Stefansson said. "For those who've inherited the variant from both parents, their risk of developing lung cancer is 70 percent greater than those who haven't inherited the variant," he noted.

In a second study, led by Paul Brennan from the International Agency for Research on Cancer in Lyon, France, researchers looked at 11,000 people, about 4,500 of whom had lung cancer.

"Variations in the region of chromosome 15 were more common in cases of lung cancer than controls, far above what we would have expected by chance," Brennan said during the teleconference. "There was about a 30 percent increased risk for those who have one variant and about an 80 percent increased risk for lung cancer for those with two variants."

These variants are in genes that affect nicotine addiction, but they are also involved in making cells increase in number, which may increase the chances of development of a tumor, Brennan said.

While the association between nicotine addiction and increased smoking and lung cancer seemed a likely explanation, Brennan's team rejected this hypothesis. "We tended to conclude that the association was primarily not due to tobacco addiction," he said.

Brennan's team found that how much one smoked or for how long had no effect on the risk for lung cancer. In addition, the gene variants were found among people who never smoked.

The researchers also looked at people who had other diseases associated with smoking but could not find an association between a gene variant and these diseases, Brennan said. "These gene variants appear to be specific for lung cancer and not other diseases strongly associated with tobacco," he said.

In the third study, from Nature Genetics, Dr. Christopher Amos of the M.D. Anderson Cancer Center in Houston and his colleagues analyzed about 3,000 patients with lung cancer who had been smokers.

As in the other studies, Amos said his group also found a 30 percent increased risk among individuals with one variant and about 80 percent increased risk for lung cancer among the 10 percent of the population that had two copies of the variant.

"What is remarkable about our studies is how similar the results are with respect to lung cancer risk," Amos said during the teleconference.

Amos's team did find an association between these gene variants and smoking behavior. "But the association is much higher with the risk for lung cancer than for smoking," Amos said. "There really does seem to be an independent risk factor for lung cancer in this chromosome region."

One expert thinks these studies alone cannot determine whether increased risk of lung cancer associated with gene variants on chromosome 15 is due to smoking or some other cause.

"Because there is such a powerful environmental effect of smoking on lung cancer, we can't say for certain whether the association in that part of the genome is related directly to smoking or to the cancer process itself or an interaction of the two," said Dr. Stephen J. Chanock, chief of the Laboratory of Translational Genomics at the U.S. National Cancer Institute and co-author of an accompanying Nature editorial.

Chanock thinks the increased risk for lung cancer results from interaction of smoking and the variants' role in cancer.

"This region is contributing to smoking behavior, and it may also contribute to the process that leads cells astray to develop cancer, particularly in the lungs," Chanock said. "The question is, which is it driving more, lung cancer or the smoking."

More information

For more about lung cancer, visit the American Lung Association  .

WEDNESDAY, April 2 (HealthDay News) -- A topical cream appears to be a highly effective treatment for precancerous lesions on the vulva, Dutch researchers report.

Rather than directly targeting the disease itself, the cream works by helping the body's own immune system fight off the human papillomavirus (HPV) -- which is often the root cause of the rare condition. The cream is currently used for precancerous skin lesions and superficial basal cell carcinoma, a highly treatable form of skin cancer.

"This is a disease that is normally treated by surgery, but that just takes away a lesion without getting at HPV, a common underlying root of the disease," said study author Dr. Manon van Seters, from the department of gynecology at Erasmus University Medical Center in Rotterdam. "So, you have a chance that the lesion will come back, time and time again. But we found that the cream is a much less invasive and friendly way to get good lasting results."

The study was expected to be published in the April 3 issue of the New England Journal of Medicine.

Seters stressed that the cream was tested only as a treatment for the precancerous disease -- not vulvar cancer itself.

"And we don't believe it'll work in vulvar cancer itself, because the invasive cancer itself is not as much related to the HPV virus," she said.

Vulvar cancer is a relatively rare disease that typically develops slowly over many years, often preceded by precancerous changes occurring in a woman's outer genitalia, within the tissues surrounding the opening of the vagina.

According to the American Cancer Society, vulvar cancer accounts for just over half of 1 percent of all cancers among American women. The organization projects that almost 3,500 new cases will be diagnosed this year, while about 870 American women will die from the illness in the same timeframe.

One-third to half of all vulvar cancer cases are related to infection with HPV, which is the same virus responsible for nearly all instances of cervical cancer.

Depending on the severity of the disease, the cancer society noted that current treatment options range from laser surgery to invasive and often repeated surgery to remove all or part of the vulva. Groin lymph node removal, radiation and chemotherapy are additional options.

Seters and her team explored the potential for the cream treatment among 52 women already diagnosed with the precancerous condition.

All the women sought care at Erasmus or at a second facility in Amsterdam between 2001 and 2003, and all were over the age of 18, sexually active, and premenopausal. The majority had grade 3 disease, while none had a history of vulvar cancer.

Half were randomly assigned to receive 250 milligrams of imiquimod 5 percent, while the other half was given a placebo cream. The creams were applied to lesions in a thin layer twice a week for 16 weeks.

By the end of treatment, about four in five of the imiquimod patients experienced a reduction in lesion size of more than 25 percent. None of the placebo patients saw their lesions shrink to this degree.

Lesion reduction of more than 75 percent occurred in five imiquimod patients, and lesions completely disappeared in nine imiquimod patients. These women remained lesion-free one year later. Eight imiquimod patients were determined to be completely free of the disease both at treatment end and one year after.

As well, 15 imiquimod patients were found to be clear of HPV immediately following treatment, compared with just two placebo patients.

Even among those still battling the lesions post-treatment, almost 70 percent of the imiquimod patients saw their disease severity drop from grade 3 to grade 2. This was the case in only one placebo patient.

Imiquimod appeared to improve quality of life as well, as severe itching and pain was lower among treated patients than placebo patients both right after treatment and one year later.

Seters and her colleagues say they still must map out the exact mechanics behind the cream's impact, while exploring why some patients benefited while others did not. Nevertheless, they concluded that the cream should be considered the "first-choice treatment" for these lesions.

However, Debbie Saslow, director of breast and gynecologic cancer at the American Cancer Society in Atlanta, offered a word of caution.

"While it moves the field forward, and it's important and very exciting, they still need larger numbers than this to be able to tell women that this is the new standard of care," she said. "But, of course, if we can ultimately recommend a topical cream for 16 weeks instead of an invasive surgical or laser procedure, that's going to be a big advantage."

More information

For additional details on vulvar cancer treatment, visit the American Cancer Society  .

WEDNESDAY, March 26 (HealthDay News) -- Hairdressers and barbers who used now-banned hair dyes that had high concentrations of coloring ingredients appear to be at a slightly elevated risk of bladder cancer, a new report contends.

The authors said the findings confirm what was first suspected back in the 1970s -- that hair dyes appear to increase the risk of cancer. These coloring agents were discontinued in the 1970s when they tested positive for cancer in rodents.

"This report updates an earlier review done in the 1990s, which called the evidence inadequate to determine the risk of cancer," said Dr. Michael J. Thun, head of epidemiological research at the American Cancer Society.

There is a question, however, whether the same cancer risk exists with the chemicals currently used in hair dyes, Thun said.

"These studies were done over years, and cancer takes years to develop. So the relevant exposures would have been in the past, and the products have changed," Thun said. "So this report doesn't provide any evidence about the risk of current exposure."

The new report is published in the April issue of The Lancet Oncology.

Dr. Robert Baan, of the International Agency for Research on Cancer, in Lyon, France, and his colleagues reviewed studies on cancers in hairdressers, beauticians and barbers that were done after 1993.

Hair dyes are classified as permanent, semi-permanent or temporary. Permanent dyes make up about 80 percent of the market. These dyes contain chemicals that, when mixed with peroxide, cause a chemical reaction that produces the dye. Dark hair dyes have the highest concentration of coloring agents, Baan's group noted.

The researchers found that the use of these dyes was linked to a small but discernible increased risk of bladder cancer. "Bladder cancer is not rare, but it's not common," Thun said.

"A small, but consistent, risk of bladder cancer was reported in male hairdressers and barbers. Because of few supporting findings by duration or period of exposure, the Working Group considered these data as limited evidence of carcinogenicity and reaffirmed occupational exposures of hairdressers and barbers as 'probably carcinogenic' to humans," the researchers wrote.

Baan's team also looked at whether people using hair dyes at home had similar risks for cancer. They found there wasn't enough evidence to make a definitive conclusion about the personal use of hair dyes and the potential for cancer.

The researchers also looked at other chemicals that belong to the same chemical group as hair dyes. They noted that one chemical -- ortho-toluidine, which is used in making dyes, pigments and rubber chemicals -- is classified as carcinogenic to humans.

Thun noted that people are exposed to naturally occurring carcinogens all the time -- in food, in air and water. "The goal is not to increase that load. So the goal here is to have these products be free of substances that are potential carcinogens and to minimize the exposure of people who work with them," he said.

More information

For more information on hair dyes, visit the U.S. Food and Drug Administration.