Natural killer (NK) cells are white blood cells which home in on infected or cancerous cells, releasing agents that induce apoptosis, or "cell suicide". NK cells are especially active against viruses.

The research emerged from findings that stress and depression impair NK cell function and can accelerate the progress of HIV/ Aids. Scientists recruited depressed and non-depressed HIV-positive women and treated them with three drugs to treat stress and depression. Two, Citalopram and the "substance P antagonist" CP-96345 increased NK cell activity, while RU486 had no effect.

Some leukaemia patients who do not respond to conventional treatments may benefit from bone marrow transplants selected to target the cancer directly.

The technique, pioneered in Italy, uses transplants from family members who are not a perfect match.

"Natural killer" cells in the new bone marrow then attack the leukaemia.

Survival rates rose after the treatment, but UK experts say these need to be reproduced on a bigger scale and in different types of the disease.

He found active smokers and ex-smokers to be the most at risk, although the risk is reduced for people who quit smoking.

Drinking alcohol was also a high risk factor, particularly for people who also smoke, although Stewart said no specific type of alcoholic drink was most strongly to blame.

Drinking chlorinated water and using a mobile phone was far less likely to cause cancer, Stewart said, although the risks associated with the long-term use of mobile phones had not been fully established.

He said there little risk from drinking coffee, using deodorants, drinking fluoridated water and having breast implants or dental fillings.

Those chips are now being implanted in some people, especially Alzheimer's patients, and encoded with their medical records. The Food and Drug Administration called the microchip one of 2005's top innovative technologies.

The microchips have been implanted in hundreds of people like Ida Frankel, who has Alzheimer's disease. If she gets lost and ends up in a hospital, doctors can scan her arm and get all of her medical records.

But when the government approved these chips for use in humans three years ago, it didn't mention that there were studies showing that similar chips caused malignant tumors in lab rats and mice.

Cancer doctors who spoke to The Associated Press, which broke this story, say you can't make the leap between cancer in mice and cancer in humans.

The electric fields' different effects on normal and dividing cells mostly have to do with geometry. A dividing cell has what Palti calls "an hourglass shape rather than a round shape." The electric field generated by the NovoCure device passes around and through round cells in a uniform fashion. But the narrow neck that pinches in at the center of a dividing cell acts like a lens, concentrating the electric field at this point. This non-uniform electric field wreaks havoc on dividing cells. The electric field tears apart important biological molecules, such as DNA and the structural proteins that pull the chromosomes into place during cell division. Dividing cells simply "disintegrate," says Palti.

Palti, who for years has been studying the effect of electric fields on cancer and normal cells, says that he has verified this mechanism in computer models and experiments in the lab. "The physics are solid," says David Cohen, associate professor of radiology at Harvard Medical School.

Patients in the glioblastoma clinical trial wear the device almost constantly, carrying necessary components in a briefcase. A wire emerging from the briefcase connects to adhesive electrodes covering the skull. Alternating electric fields pass through the scalp, into the skull, and on to the brain. The Food and Drug Administration approved the device for late-stage clinical trials for glioblastoma following promising results from a pilot study in 10 patients, one of whom had a complete recovery.

More than 200,000 volunteers, including long-term users, are to be monitored for at least five years to plot mobile phone use against any serious diseases they develop, including cancer and Parkinson's and Alzheimer's diseases.

Professor Lawrie Challis, who is in the final stages of negotiation with the Department of Health and the mobile phone industry for the &3 million that he needs to fund the study, told The Times that research has shown that mobiles are very safe in the short term but that there is a "hint of something" for people using them longer.

In an interview, Professor Challis, a world expert on mobile phone radiation, and chairman of the government-funded mobile telecommunications health research programme, emphasised that the "hint" was just that. One European study has found a slight association and using a mobile for more than ten years. The few long-term users developed more acoustic neuroma brain tumours which were found close to the ear used for phoning.

But, because of the tiny numbers involved, "it could be by chance," he said. Asked whether the mobile phone could turn out to be the cigarette of the 21st century in terms of the damage it could inflict, he replied: "Absolutely."

He said that the study was necessary because all the important breakthroughs in what caused cancers had shown that the effects often took more than ten years to show. "You find absolutely nothing for ten years and then after that it starts to grow dramatically. It goes up ten times. You look at what happened after the atomic bombs at Nagasaki, Hiroshima. You find again a long delay, nothing for ten years. The same for asbestos."

An experimental ultrasound technique that measures how easily breast lumps compress and bounce back could enable doctors to determine instantly whether a woman has cancer or not without doing a biopsy.

In a small study of 80 women, the technique -- called "elastography" -- distinguished harmless lumps from malignant ones with nearly 100 percent accuracy.

If the results hold up in a larger study, elastography could save thousands of women from the waiting, cost, discomfort and anxiety of a biopsy, in which cells are removed from the breast -- sometimes with a needle, sometimes with a scalpel -- and examined under a microscope.

"There's a lot of anxiety, a lot of stress, a lot of fear involved" with biopsies, said Susan Brown, manager of health education for the Susan G. Komen Breast Cancer Foundation. "And there's the cost of leaving work to make a second appointment. If this can be done instead of a biopsy, there would be a real cost reduction."

To explain elastography, Ophir likens the body to a box-spring mattress, but "a crazy mattress made out of millions of small springs and each one is a little different. Each is moving around at a different rate, depending on their individual stiffness." Cancerous tumors are like stiff springs. Normal tissue and benign lesions compress more easily.

Drug therapy for cancer can prompt a wide range of neurological side effects, even the onset of dementia.

But they were thought not to be directly linked to the drug treatment itself.

Instead, some doctors have put them down to the patient's vulnerable psychological state.

The latest study found that dose levels typically used when treating patients killed 40% to 80% of cancer cells - but 70% to 100% of human brain cells grown in the lab, and caused serious damage to brain cells when given to mice.

Several types of healthy brain cell continued to die for at least six weeks after exposure.

Cutaneous malignant melanoma (CMM): Melanoma of the skin is a malignant cancer of great severity. Although treatment is improving, melanoma still carries a significant risk of death. Between 50% and 90% of the burden of disease from melanoma estimated in the WHO report is due to UVR exposure.

Squamous cell carcinoma of the skin (SCC): This is another type of malignant skin cancer which generally progresses less rapidly than melanoma and is less likely to cause death or ongoing disability. Of the total SCC disease burden, 50-70% is attributable to UVR exposure.

Basal cell carcinoma of the skin (BCC): This skin cancer appears predominantly in older people and grows slowly by local spread. The incidence and mortality of BCC were estimated to be 50-90% attributable to UVR exposure.

Squamous cell carcinoma of the cornea or conjunctiva (SCCC): This is a rare tumour of the surface of the eye. Some 50-70% of the disease burden due to SCCC is attributable to UVR exposure.

Photoageing: Chronic sun damage is associated with the development of skin conditions called solar keratoses. On rare occasions, these are pre-malignant conditions. The burden of disease due to solar keratoses is 100% attributable to UVR exposure.

Sunburn: Sunburns may be severe and blistering, and the resulting disease burden is 100% attributable to UVR exposure.

Cortical cataract: Cataract is an eye disease where the lens becomes increasingly opaque, resulting in impaired vision and eventual blindness. Long-term sun exposure to the eye increases the risk of developing a specific cataract type called cortical cataract. Five percent of all cataract-related disease burden is directly attributable to UVR exposure.

Pterygium: This is a wing-shaped fleshy growth on the surface of the eye. 40-70% of the disease burden is attributable to UVR exposure.

Reactivation of herpes of the lip (RHL): Excessive UVR exposure causes immunosuppression and reactivation of the herpes simplex virus ("cold sores"). 25-50% of the disease burden is attributable to UV exposure.

Pomegranates contain a cocktail of chemicals which minimise cell damage, and potentially kill off cancer cells.

The study, by the University of California in Los Angeles, appears in the journal Clinical Cancer Research.

Previous research had indicated that pomegranate juice could have a beneficial effect on prostate cancer in tests on mice.

But the latest study has shown that humans can potentially benefit too.

Although they did not have fertility problems, the woman and her partner created embryos by IVF. This allowed doctors to remove a cell and test it for the cancer gene, so only unaffected embryos were transferred to her womb.

The couple are the first to take advantage of a relaxation in the rules governing embryo screening.

When the technique was developed in 1989 it was allowed only for genes that always cause disease, such as those for cystic fibrosis. However, it was approved last year for the eye cancer, which affects only 90 per cent of those who inherit a mutated gene.

The pregnancy will increase controversy over the procedure, which the Government’s fertility watchdog authorised on Wednesday for genes that confer an 80 per cent lifetime risk of breast and bowel cancer.

One in five Americans will develop skin cancer, and a person's risk of the disease doubles if he or she has had five or more sunburns, according to a report in the April issue of the Mayo Clinic Health Letter.

Basal and squamous cell carcinomas, the most common and treatable types of skin cancers, had long been considered a problem only for people over 50, according to the report. But Mayo Clinic researchers found that the percentage of women under 40 with the more common type, basal cell, tripled between 1976 and 2003, while the rate of squamous cell cancers increased four-fold.

In the same study, the researchers found that just 60% of the cancers they identified occurred on skin frequently exposed to the sun, such as the head and neck, rather than the normal 90%. Most of the remaining cancers were seen on the torso. The researchers suspect this may be due to more widespread use of tanning beds.

Two types of ultraviolet (UV) light are implicated in skin cancers, the article explains. UVA, which penetrates deeper into the skin and impairs its immune defenses, is more responsible for melanoma, the most deadly type of skin cancer. UVB exposure causes sunburn, as well as squamous and basal cell skin cancers.

US scientists have successfully implanted bladders grown in the laboratory from patients' own cells into people with bladder disease.

The researchers, from North Carolina's Wake Forest University, have carried out seven transplants, and in some the organ is working well years later.

The achievement, details of which have been published online by The Lancet, is being described as a "milestone".

The team is now working to grow organs including hearts using the technique.

The Dutch Health Council, in an overview of research from around the world, last year found no evidence radiation from mobile phones and TV towers was harmful. A four-year British survey released in January showed no link between regular, long-term use of cell phones and the most common type of tumor.

However, researchers at the Swedish National Institute for Working Life said they looked at the mobile phone use of 905 people between the age of 20 and 80 who had been diagnosed with a malignant brain tumor and found a link.

"A total 85 of these 905 cases were so-called high users of mobile phones, that is they began early to use mobile and, or wireless telephones and used them a lot," the study said.

"The study also shows that the rise in risk is noticeable for tumors on the side of the head where the phone was said to be used," it added.

The inspiration for the site came from the experiences of a girl with cancer.

She had heard about the Dipex - the Database of Individual Patient Experience - site for adults which colleagues of her father ran, and wanted something similar for people her own age.

Sadly, she died before the site was completed, but staff have dedicated the cancer section to her.

Vishal, now aged 19, from Leicester, said knowing there were other teenagers going through the same problems as him would have made it easier.

"It is a really hard place to be," he explained.

"It is a very exciting discovery," said Dr. Eric Klein of the Cleveland Clinic, who will present the findings Friday at an American Society of Clinical Oncology prostate symposium in San Francisco. "There is now a suggestion that prostate cancer could be caused by an infectious disease."

Infectious disease-causing viruses are already blamed for causing some liver cancers and cervical cancer. That has planted nagging suspicions in the minds of scientists that some diseases may play important roles alongside genetics, environment and chance in causing breast, stomach and several other forms of cancer.

Researchers are not sure how the virus infected people, but suspect it has been passed on genetically for thousands of years.

"This is a class of virus no one would have looked for in prostate cancer," said UCSF researcher Joe DeRisi, who developed the so-called "gene chip" that made the discovery. DeRisi's chip contains 20,000 snippets of vital genetic material from every known virus. It is the same chip that confirmed a previously undiscovered virus in the cold family that caused the SARS outbreak three years ago.

For the first time in more than 70 years, annual cancer deaths in the United States have fallen, a turning point in the war on cancer likely achieved by declines in smoking and better tumor detection and treatment.

The number of cancer deaths dropped to 556,902 in 2003, down from 557,271 the year before, according to a recently completed review of U.S. death certificates by the National Center for Health Statistics.

"Even though it's a small amount, it's an important milestone," said Dr. Michael Thun, who directs epidemiological research for the American Cancer Society.

Lung: Men, 89,964; Women, 68,122

Colon, rectum: Men, 28,007; Women, 27,951

Breast: Men, 380; Women, 41,620

Prostate: Men, 29,554

In the latest study the same Dunn team examined cells from the lining of the colon taken from healthy volunteers eating different diets.

They found higher levels of DNA damage in the cells taken from people eating red meat.

Work by the Open University team suggests the reason could be the presence of substances called N-nitrosocompounds, which form in the large bowel after eating red meat.

Their work suggests that these compounds combine with DNA, and alter it so that it is more likely to undergo harmful changes or mutations that increase the likelihood of cancer

The melanoma on his leg was 6mm in depth.

He knows that, because of the delay in diagnosis, his chances of surviving the next five years are 50/50.

"My Breslow depth (a method for measuring the depth of the tumour, used to predict a patient's chance of survival) for the mole on the back of my leg was off the scale. It came in at a whopping 6mm depth.

"It was because it was bleeding that my family pressured me to get it checked out, I really thought it wouldn't have been as serious as it was.

"The authors show that tumor cells can mobilize normal bone marrow cells, causing them to migrate to particular regions and change the local environment so as to attract and support a developing metastasis," Patricia Steeg, of the National Cancer Institute in Bethesda, Maryland, said in a commentary.

Cells at the site of the metastasis multiply and produce a protein called fibronectin, which acts like a glue to attract and trap the bone marrow cells to create a landing pad or nest for the cancer cells.

"These nests provide attachment factors for the tumor cells to implant and nurture them. It causes them not only to bind but to proliferate. Once that all takes place we have a fully formed metastatic site or secondary tumor," said Lyden.

"This is the first time anyone has discovered what we call the pre-metastatic niche."

The procedure, in my case, was no worse than having a root canal or tooth pulled. For others it might be more painful depending on the location of the cancer. First the doctor drew a line around the part of the skin where the growth is. Then she numbed me up and removed a small section of skin. Off to the waiting room I went.

After about 20 minutes the word came back - negative. There was no cancer. Does this mean I never had it? No. It means that most was probably removed during the initial biopsy and the rest might have been in the middle of the piece they cut out today. As the doctor explained, the lab technician looks at the top of the piece of skin they remove and the bottom to make sure there's no cancer left. Once I got the good word, I went back onto the table, gave me a bit more anesthesia and they sutured me up with a bunch of stitches. My guess is that I received about ten stitches.

More than 1300 Australians die each year from skin cancer and those who use solariums are increasing their risk of the illness. Solariums emit ultraviolet rays up to five times stronger than the midday summer sun, information from the Cancer Council shows. Despite this, young people are flocking to tanning clinics particularly in the lead up to summer.

Associate Professor John Kelly from the Victorian Melanoma Service said an increasing number of his patients were frequent solarium users.

"These are people who are paying the ultimate price for fashion," Prof Kelly said. "The irony is that by making themselves look more attractive, they're actually putting their health at risk and causing premature ageing."

He said many Australians falsely believed solarium tanning was safer than sunbaking.

Scientists are reporting Friday that the vaccine was 100% effective in preventing cervical cancer and precancerous changes tied to two types of a common sexually transmitted virus.

"It's a very impressive finding," Christopher Crum, director of women's and perinatology pathology at the Brigham and Women's Hospital in Boston, said Thursday.

A team from the University of Pennsylvania School of Medicine has shown that by using a cancer vaccine based on the bacterium Listeria monocytogenes, they can cure mice with established breast tumors. Cancer vaccines, which are more properly described as immunotherapy, work by boosting an immune response against tumor-associated antigens. Using Listeria, the researchers, led by Yvonne Paterson, PhD, Professor of Microbiology, delivered the tumor-associated antigen HER-2/Neu to immune cells. HER-2/Neu is overexpressed in 20 to 40 percent of all breast cancers and also present in many cancers of the ovaries, lung, pancreas, and gastrointestinal tract. These cells eventually enlist killer T cells to seek out and destroy the tumor cells that display the HER-2/Neu molecule.

"We found that we can stop the tumor from growing out to 100 days, at which time we stopped measuring since this is a long time for experiments of this type," says Paterson. "The tumors stopped growing or went completely away." The researchers published their findings in the September 15 issue of The Journal of Immunology.

"It took a while to dissect what elements of an immune response were best able to cause the rejection of established tumors," she says. "But in the last couple of years it has paid off and we are very excited to see the technology finally being tested in cancer patients. The dream of the cancer immunotherapist is to provide an alternative and more humane way of controlling metastatic disease than current chemotherapies."

Scientists from Denmark drew their conclusions after studying 6,689 women over a period of 18 years, and speculated that it may be because daily stress suppressed production of estrogen, which is a risk factor in breast cancer.

"Prolonged-low key stress of everyday life results in a persistent activation of stress hormones which may impair estrogen synthesis and may therefore be related to lower risk of breast cancer," they wrote.

However, they warned that stress was not a health cure, given that high levels had also been associated with increased risk of potential killers like heart disease.

They also noted that their findings were at odds with studies in Finland and Sweden -- the former found no link between daily stress and breast cancer while the latter found a direct association with higher risk.

However Colin Drummond, professor of addiction psychiatry at St George's Hospital Medical School, London, said: "I have concerns about calling everything in the world an addiction."

"There's a tendency to translate extremes of behaviour into addictions."

Professor Drummond said addictions meant a particular chemical mechanism occurred in the brain which determined a person's behaviour.

Such a mechanism had not yet been established for sunbathing, so the habit could not be labelled an addiction.

He said people tanned because they wanted to conform socially, not because they were addicted to the feeling.

Mayo Clinic researchers studied only basal and squamous cell carcinomas, cancers that are almost always curable and that together afflict 1 million Americans a year, according to the article, published in today's Journal of the American Medical Association. The cancers, caused largely by overexposure to ultraviolet light from the sun, usually develop in older people who have spent many years outdoors.

In the study, doctors focused on people under 40 in Olmsted County, Minn. From 1976-1979 to 2000-2003, the combined rate of the two diseases grew from 19 cases per 100,000 people to 33 per 100,000 — a 74% increase.

Although up to 90% of such cancers typically appear on the head and neck, doctors in the study found 40% of skin cancers on other parts of the body, a change that probably reflects the effect of excessive sunbathing.

Christenson says it's possible that some of the increase in basal and squamous cell carcinomas could be caused by increased screenings. But, she says, her findings suggest that tanning probably plays a more important role.

Basal and squamous cell carcinomas can be disfiguring, even if they rarely spread or turn fatal, Christenson says. And they kill about 1,000 to 2,000 people a year, the American Cancer Society says.

"For a preventable cancer, that's too bad," Christenson says.

Dai and his team shine a very thin laser beam of near-infrared light on something called a carbon nanotube.

The electrons in the nanotube -- a hollow tube, resembling straw, made of interwoven carbon atoms about one-100,000th the diameter of a human hair -- become excited by the light and release energy in the form of heat.

The heat is so extreme that it is deadly to cells.

To test this approach as a therapy, Dai placed the carbon nanotubes inside a collection of cancer cells, then shone the three-centimeter laser beam on them. The cancer cells were destroyed.

``They were literally cooked to death,'' Dai said. ``The tube acts like a tiny heater.''

But cells without the carbon nanotubes showed no ill effects -- the light passes harmlessly through them.

Tests in laboratory dishes show that curcumin made melanoma skin cancer cells more likely to self-destruct in a process known as apoptosis.

The same team has found that curcumin helped stop the spread of breast cancer tumor cells to the lungs of mice.

Bharat Aggarwal of the Department of Experimental Therapeutics at the University of Texas M.D. Anderson Cancer Center in Houston and colleagues treated three batches of melanoma cells, known as cell lines, with curcumin at different doses and for varying times.

The curcumin suppressed two proteins that tumor cells use to keep themselves immortal, the researchers write in next month's issue of the journal Cancer.

Three different types of mouth bacteria are associated with the most common form of oral cancer, researchers said Thursday in a discovery that may lead to a simple test for the often-fatal tumor.

The study, published in the Journal of Translational Medicine, also suggests the bacteria may play a role in causing the cancer, called oral squamous cell carcinoma, the researchers said.

"Finding bacteria associated with (oral squamous cell carcinoma) encourages us to hope that we have discovered an early diagnostic marker for the disease," said Donna Mager of the Forsyth Institute in Boston, who led the study.

PFOA, or perfluorooctanoic acid, is a "likely carcinogen" according to an advisory board to the Environmental Protection Agency. The science panel's pronouncement is the first step in a process that could result in the agency regulating or even banning some uses of the popular manufacturing agent.

The independent science board disagrees with a risk assessment of PFOA that the EPA drafted and released earlier this year in which the chemical was described as a "suggested" carcinogen.

PFOA is used in the manufacture of Teflon coatings on pans. It is also found in widely used coatings that make upholstery and clothing stain-resistant and in a grease-resistant coating on microwave popcorn and fast-food packaging among others.

He said at a meeting of the American Society for Virology that studies have shown women infected with AAV-2 who are also infected with a cancer-causing wart virus called HPV develop cervical cancer less frequently than uninfected women do.

AAV-2 is a small virus that cannot replicate itself without the help of another virus. But with the help of a second virus it kills cells.

For their study, Meyers and colleagues first infected a batch of human cells with HPV, some strains of which cause cervical cancer.

They then infected these cells and normal cells with AAV-2.

After six days, all the HPV-infected cells died.