NEW WAY TO TREAT SKIN CANCER
PARIS
Scientists say they have unearthed important new clues in the search for a treatment for skin cancer, which in some cases can be fatal and which is affecting more and more people, especially in developed countries.
After carrying out a series of experiments on mice a team of scientists in the United States has arrived at what they call a "simple technology" to cure a metastatic disease. The results of their study appear in the September issue of Nature.
During chemotherapy, healthy cells are destroyed along with cancerous cells. Researchers led by Richard Vile at the Mayo Foundation in Rochester, Minnesota have attempted to turn this feared secondary effect to their advantage by better stimulating the immune system so that it attacks the tumor.
"Deliberate destruction of normal tissue can be exploited to generate immunity against a malignant disease originating from that tissue," said researchers in an on-line report (www.nature.com).
Provoking an immune response--the role of a vaccine--assumes that cells responsible for defending the organism recognize the aggressor, or intruder in the case of a melanoma, and are prepared to fight it. One of the principal obstacles has been to identify specific markers on cancerous cells-known as peptides or proteins-which can make it possible for lymphocytes, white corpuscles inside white blood cells, to recognize them.
But recent studies have shown that healthy melanocytes, the skin's pigment-producing cells that make people tan, have similar markers that the immune system can train itself to recognize.
Those advances led to the idea, tested with success by Vile and his team on mice, of sacrificing normal cells to destroy melanomas without first having to identify those specific markers associated with the cancerous cells.
In experiments, a viral enzyme included in a vector was injected under the mice's skin, which converts an antiviral substance known as ganciclovir into a drug that can damage cellular DNA. This led to an inflammatory reaction leading to the destruction of normal cells, and at a later stage, tumor cells.
Repeated several times, this type of treatment was able to completely destroy the tumor without causing any long-term autoimmune reaction to healthy tissue, the researchers said. But they said that a comparison of the benefits of the treatment as compared with its disadvantages should always be assessed on a case-by-case basis.
The researchers see in this approach the possibility of developing biological therapies that are different from other approaches to finding a cure for skin cancer.
In Australia, where melanomas kill 1,000 people each year and where 9,000 new case reported annually, the government of the state of Queensland, known as the Sunshine State, announced last year that a therapeutic vaccine could be available within five years.
In Europe skin cancer is more frequent among people with fair skin from the northern half of the continent.
According to the World Health Organization, between two and three million nonmelanoma skin cancers and approximately 132,000 malignant melanomas occur each year. Currently, one in five North Americans and one in two Australians will develop some form of skin cancer in their lifetime, said the WHO.
MEN SHOULD KEEP TRACK OF PSA LEVELS
WASHINGTON
Men in their 40s should begin tracking their prostate-specific antigen (PSA) levels more vigorously since those WHO experience rising PSA levels are more prone to develop and die from prostate cancer.
A study published in The New England Journal of Medicine in July found men WHO experience a rapid rise in their PSA levels during the year before diagnosis of prostate cancer are at a "significantly increased risk of death" from the cancer even after surgery. It found that screening for PSA levels offers a better insight into how prostate cancer will develop, and how aggressively the cancer is likely to evolve.
"The study results indicate that men with a high PSA velocity should not be managed by 'watchful waiting' and many will require more than a radical prostatectomy to prevent prostate-cancer death," according to researcher William Catalona. "It's still a big problem and it kills a lot of men," wrote Catalona, director of the Clinical Prostate Cancer Screening Program at Chicago's Northwestern Memorial Hospital.
Specifically, he recommends testing for cancerous cells when a man's PSA level reaches 2.5 nanograms per milliliter. An annual PSA velocity of more than 2.0 ng per milliliter was associated with a higher risk of death from prostate cancer despite surgery.
Men should start checking their PSA level at age 40 to track any sharp rises in their PSA levels, the study recommended.
TINY STEPS TO FIGHT CANCER
WASHINGTON
The United States government will spend a whopping US$144.3 million to apply nanotechnology to the fight against cancer. The National Cancer Institute (NCI), part of the National Institutes of Health, is founding the Alliance for Nanotechnology to combine multidisciplinary efforts of public and private sectors to find ways to fight cancer on a nanotechnology level.
"Nanotechnology has the potential to radically increase our options for prevention, diagnosis, and treatment of cancer," NCI director Andrew von Eschenbach, said.
Nanotechnology develops devices so small that it can be measured on a molecular scale. A nanometer is one-millionth of a meter, or 80,000 times the width of a human hair. Robots that small could circulate in the bloodstream to cut out cancerous cells. Several nanotechnologies show potential for fighting cancer, the institute said. Tiny particles made of magnetic rust allow better magnetic resonance imagery of the prostate.
The institute also mentioned nanoparticles that destroy cancerous cells with high temperatures, leaving health tissues intact. Similarly, the nanoparticles could be used to target cancerous cells and tumors in chemotherapy.
"CHIPPING" AWAY CANCER CELLS
SINGAPORE
Singaporean doctors have used an injectable radioactive chip to destroy malignant cells and prolong the lives of inoperable liver-cancer patients. Clinical trials on eight patients at the government-run Singapore General Hospital have shown the chip--called BrachySil--is capable of killing malignant cells within a 1.5-centimeter radius, she said. Five of eight patients involved in the trials have seen their tumors shrink by between 11 and 60 percent when they were treated more than three months ago, a spokesperson for the hospital said.
The doctors adapted the porous and biodegradable silicon chip, first developed by Britain's defense ministry, for the treatment. BrachySil is owned by pSiVida, a listed company in Australia dediCATed to biomedics and nanotechnology.
The Straits Times said late-stage liver cancer patients usually die within six to 12 months, but the new treatment could keep them alive longer while waiting for a potentially life-saving transplant.
Dr. Anthony Goh, a nuclear-medicine consultant and the trial's principal investigator, told the newspaper the chips proved extremely safe because they were able to "lock" in place, sparing nonmalignant cells from radiation.
There are now plans for a six-month trial involving 30 to 40 patients from Asia and New Zealand next year. If successful, BrachySil could be on the market by 2007 and developed to treat other inoperable solid cancers, the report said.
FULL-BODY SCANS UP CANCER RISK
CHICAGO
Full-body CAT scans increase a person's risk of cancer, according to a study that raises questions about the rising popularity of these screenings among healthy people.
Just one of these scans imparts a dose of radiation comparable to that received by some Japanese atomic-bomb survivors, while repeated annual screenings carry a significantly elevated lifetime cancer risk, the study said.
"Our research provides definitive evidence that radiation risk is associated with full-body CT (computed tomography) scans," said David Brenner, lead author of the study in the journal Radiology.
The study was prompted in part by the medical establishment's concern about the increase in the numbers of otherwise healthy or asymptomatic people seeking out these scans to diagnose diseases such as colon and lung cancer and coronary artery disease.
To asses the risk associated with the procedure, Brenner and his colleagues compared data on atomic-bomb cancer mortality with calculations of the radiation dose from a full-body scan. They concluded that the dose from a single full-body CT is only slightly lower than the mean dose experienced by residents of Hiroshima and Nagasaki who survived the 1945 A-bomb attacks. Significant increases in cancer risk were seen in these survivors.
The researchers said among otherwise healthy 45-year-olds, one full-body CT screening would typically cause a fatal form of cancer in one of 1,200 people. Among 45-year-olds who had annual full-body CT scans for 30 years, the estimated mortality rate would be about one in 50, the study said.
"In addition to the radiation risks demonstrated in this report, elective full-body CT may provide false-positive findings when no disease exists," said Brenner, who is professor of radiation oncology and public health at Columbia University Medical Center in New York City. "This typically involves more extensive testing, which is costly and stressful."
No studies have yet reported life-prolonging benefits to the procedure, he noted. The effective dose of radiation delivered during a full-body CT exam is nearly 100 times that of a typical screening mammogram, according to the study.
Go Slow on that Scan, But Take the PSA Test