WEDNESDAY, Nov. 7 (HealthDay News) -- A study of more than 1 million British women finds that overweight or obesity is to blame for about 5 percent of all cancer cases.

That's about 6,000 out of the 120,000 cancers affecting British women each year.

The study, by researchers from the University of Oxford, found that overweight and obese women are at higher risk of developing and dying from cancer, including breast cancer in postmenopausal women, colon cancer in premenopausal women, and pancreatic and kidney cancer generally.

"Among middle-aged and older women in the U.K., around 5 percent of all new cancers each year are actually due to overweight or obesity," estimates lead researcher Gillian Reeves, a statistical epidemiologist at Oxford's Cancer Research UK Epidemiology Unit.

"It is important that women be aware that being overweight carries some excess risk of certain types of cancers," Reeves said. "This is something they need to take into consideration alongside what we know are very strong adverse effects of being overweight on diseases like diabetes and heart disease."

In the study, Reeves and colleagues looked at the relationship between body-mass index (BMI), and cancer in 1.2 million British women aged 50 to 64, who took part in the Million Women Study. In the U.K., about 23 percent of all women are obese and 34 percent are overweight, according to national statistics.

During 5.4 years of follow-up, the researchers found more than 45,000 new cancers and more than 17,200 deaths from cancer. Being overweight or obese was linked to an increased incidence for all cancers combined, according to the report in the Nov. 7 online edition of the British Medical Journal.

Being overweight or obese can significantly increase the risk of some cancers in women, Reeves' group found.

Specifically, obese and overweight women were twice as likely to develop endometrial cancer and cancer of the esophagus compared with normal weight women. In addition, overweight and obese women had a 53 percent greater risk of kidney cancer, a 50 percent greater risk of multiple myeloma and a 24 percent greater risk of pancreatic cancer compared with their normal weight counterparts.

Obesity's link to cancer risk appeared to be associated with menopause for certain tumor types. For example, postmenopausal overweight or obese women had a 40 percent increased risk of developing breast cancer, while premenopausal and overweight women had a 61 percent increased risk of developing colorectal cancer, the researchers found.

The rise in cancer risk for overweight and obese women mirrored findings reported last Wednesday by the American Institute for Cancer Research and the Britain-based World Cancer Research Fund.

In that review of 7,000 studies, researchers found a definite link between excess fat and cancers of the esophagus, pancreas, colon and rectum, endometrium and kidneys in all women, as well as breast cancer in postmenopausal women.

Reeves' team also found that, in general, overweight and obese women were more likely to die from cancer once they developed the illness compared to slimmer women. The obesity-linked increase in the rate of cancer death was similar to the increase in cancer risk, the researchers reported.

One expert said the findings highlight another reason to stay slim.

"This study adds to the considerable body of evidence that shows the relationship between overweight obesity and cancer risk," said Eugenia E. Calle, managing director of analytic epidemiology at the American Cancer Society and author of an accompanying journal editorial.

To reduce their risk of cancer, women need to stay lean, Calle said. "Women should not gain weight in adulthood and maintain a weight that puts you on the lean end of normal weight," she said. This is also a benefit in preventing heart disease, diabetes and other medical problems, and maintaining a good quality of life, she added.

In related news, a study in the Nov. 7 issue of the Journal of the American Medical Association found obesity to be associated with 11 percent of deaths from cancers that are already considered to be obesity-related. The trend was not seen for non-obesity-related cancers, however.

"We estimate about 5 percent of all cancer deaths are associated with obesity," said the lead author of that study, Katherine M. Flegal, of the U.S. National Center for Health Statistics. "That ranges from -0.2 to 7.9 percent, so there is not much of a difference between the two studies."

More information

For more on cancer in women, visit the U.S. National Cancer Institute.

TUESDAY, Oct. 30 (HealthDay News) -- While most people associate viruses with human illness, a new study suggests that at least one virus might have cancer-fighting abilities that could be used to treat some metastatic cancers.

Reporting in the Nov. 7 issue of Journal of the National Cancer Institute, researchers explained that the virus, Seneca Valley Virus-001 (SVV-001), was effective in treating lines of cells from small-cell lung cancer and some pediatric cancers, as well as lung cancer and eye cancer in immune-deficient mice.

"In animal studies, we found complete eradication of small-cell lung cancer," said the study's lead author, Paul Hallenbeck, founder, president and chief scientific officer of Neotropix, in Malvern, Pa. "This is a promising new, yet old, approach to a very serious disease," added Hallenbeck, noting that people first noticed that viruses had some effect on cancer as long as 100 years ago.

However, at least one expert advised caution when interpreting these findings about the virus and metastatic cancer, which is cancer that has spread from one site in the body to another.

"These initial results look promising and warrant further investigation, but this is a very early study done in cell lines and an animal model," said Dr. Jay Brooks, chairman of hematology and oncology at Ochsner Health System in Baton Rouge, La. Brooks said there are still many questions that need to be answered about this virus, such as what are the long-term effects in humans, how expensive is it, will it continue to work in the long run, and would you have to be on it for the rest of your life?

Hallenbeck and his colleagues hope to answer the safety question shortly. They're in the midst of a phase I clinical trial that includes 18 people. Phase I trials are designed solely to look at whether or not a product is safe to administer in humans; they are not designed to assess effectiveness.

For the new study, Hallenbeck and other researchers reported on their results with cell lines and mice. Hallenbeck said he originally discovered the virus while working at a subsidiary of Novartis Pharmaceuticals, called Genetic Therapy. He said the virus is a previously undiscovered strain from the Picornaviridae family of viruses.

Previous viruses have shown cancer-fighting (oncolytic) ability. But, because the human immune system is primed to fend off viruses, oncolytic viruses may have trouble surviving until they reach their intended target -- the spreading cancer cells. To avoid this, researchers have been directly injecting viruses into tumors. But, according to Hallenbeck, if you're able to access a tumor well enough to inject the virus into it, that tumor can probably be well treated with surgery or radiation.

The SVV virus appears to be able to reach metastatic cancer cells without being inactivated by the immune system cells present in blood. With this virus, Hallenbeck is hoping to be able to track down metastatic cancer cells that can't easily be detected.

And, in cell lines, the virus appears to be effective at treating small-cell lung cancer and some pediatric cancers, without being inactivated by the immune system. The researchers also tested the virus in mice with deficient immune systems and found it was able to eradicate small-cell lung cancer in 10 out of 10 mice tested and knock out eye cancer in five out of eight mice tested.

"It is unclear whether these results from immune-deficient mouse models would be similar to those of patients with metastatic cancer. In particular, it is unknown whether the patients' immune system would reduce the effectiveness of SVV-001," the study authors wrote.

Hallenbeck said the phase I trial is expected to be completed some time next year. If all goes well in that trial, testing of the virus will move on to trials designed to measure effectiveness, he said.

More information

To learn about cancer advances made in recent years, visit the U.S. National Cancer Institute.

FRIDAY, Oct. 26 (HealthDay News) -- Women who have had advanced precancerous lesions of the cervix are still at risk for invasive cancers up to 25 years later, Swedish researchers report.

Currently, the American Cancer Society recommends that women who have had precancerous lesions called severe dysplasia/carcinoma in situ (CIS) continue getting Pap tests for 10 years after treatment. But, based on this study, these guidelines may need to be changed, said Debbie Saslow, the society's director of breast and gynecologic cancer, who was not involved with the research.

Saslow added, however, that even though these women continue to be at risk for developing cervical or vaginal cancer, the risk is low. "Women who have been treated for advanced precancer do need to remain vigilant," she said.

"This paper is going in my file for when we update our guidelines in the next two years," Saslow added. "We will see if we want to stick with 10 years or go to a much wider interval."

The study was led by Dr. Bjorn Strander, a senior consultant with the Department of Obstetrics and Gynecology at Sahlgren's Academy at the University of Gothenburg. The researchers collected data on 132,493 women who had a diagnosis of severe dysplasia/CIS between 1958 and 2002. The statistics came from the National Swedish Cancer Register.

The researchers found 881 women had developed cervical cancer, and 111 had developed vaginal cancer more than one year after the initial diagnosis. This was almost seven times higher than expected, the researchers said.

Women with a diagnosis of severe dysplasia/CIS were more than twice as likely to develop cancer compared with the general female population. The women were also twice as likely to develop invasive cervical cancer after diagnosis of CIS if that diagnosis was made between 1991 and 2000, compared with the same diagnosis made from 1958 to 1970. This increased risk might be due to changes in treatment over that period, particularly because fewer hysterectomies are being done as part of treatment for CIS, the study authors said.

Strander's team also found a particularly high risk for women over age 50, and this risk continued to increase with age. "The risk after treatment hardly decreases at all after treatment and is still sustained after more than 25 years," he said.

"While well-screened women after 50 to 60 years of age are very well protected from cervical cancer and have little, if any, further use of screening, this does not apply to women who have been treated for grade 3 CIS," Strander said. "They need, and should have, long-term follow-up, perhaps lifelong," he said.

The results are published in the Oct. 26 edition of the British Medical Journal.

More information

For more on cervical cancer, visit the American Cancer Society  .

TUESDAY, Oct. 16 (HealthDay News) -- A first-time colonoscopy to remove precancerous polyps plays a bigger role in reducing the risk of dying from colon cancer than do follow-up screenings done years later, a new study suggests.

Researchers found that patients who forego follow-up colonoscopies in the decade following the initial procedure will still reap the benefits sown by a first removal of polyps -- called a polypectomy.

Post-polypectomy colonoscopies do, however, become more important in protecting against colon cancer death as patients enter their second decade following the first colonoscopy, the study authors said.

"The initial colonoscopy has a major impact -- a huge, huge effect -- on reducing colon cancer deaths," said study lead author Ann G. Zauber, an associate attending biostatistician at Memorial Sloan-Kettering Cancer Center's department of epidemiology and biostatistics, in New York City.

"The risk for dying from colon cancer drops 90 percent after the initial colonoscopy," she said. "And in the first 10 years, 90 percent of that reduction is due to that first procedure. Only 10 percent of the risk drop is due to follow-up colonoscopies."

Zauber presented her findings Monday at the American College of Gastroenterology annual meeting, in Philadelphia.

Her team's conclusions were derived from a review of data on colon cancer incidence and deaths that had been collected by the National Polyp Study. The study had tracked the development of polyps and invasive colorectal cancer following a first-time colonoscopy.

For the new study, Zauber and her colleagues fed the National Polyp Study data into a computer model that projected colon cancer incidence and deaths 30 years down the road. The review included three different types of patients -- those who had no preventive screening of any kind; those who underwent only an initial colonoscopy and polypectomy; and those who had both a colonoscopy/polypectomy and follow-up screenings.

The Sloan-Kettering researchers noted that prior research had indicated that a combination of initial polypectomy and follow-up screenings reduced the incidence of colon cancer by between 76 percent and 90 percent. Previous work had also shown that this dual preventative approach reduced the rate of colorectal cancer deaths by between 69 percent and 92 percent.

However, the new analysis parsed those observations -- revealing that the lion's share of the benefit goes to the initial colonoscopy, not the follow-up surveillance.

The new findings also suggest that too much reliance on follow-up screenings -- which can strain health-care resources while exposing patients to the usual risks associated with any invasive procedure -- may be unjustified, the researchers said.

Still, Zauber said that follow-up colonoscopies aren't without some long-term merit. Over time, the relative importance of such surveillance rises, she noted -- ultimately accounting for approximately 45 percent of colon cancer risk reduction in the second decade following a first colonoscopy.

Zauber stressed that the new findings should not alter current American College of Gastroenterology recommendations about shorter-term surveillance: Namely, that high-risk patients -- such as those with a previous history of colon cancer or polyps -- should undergo follow-up colonoscopies every three to five years.

"The guidelines are quite good for higher-risk patients," Zauber said. "And I would not want to discourage people from surveillance. Lower-risk patients, however, could perhaps wait till the later part of that follow-up period before coming back for another colonoscopy."

Dr. Joseph Martz, chief of the division of colorectal surgery at Beth Israel Medical Center in New York City, also placed a premium on follow-up care.

"Surveillance is very important because 3 and 4 percent of polyps greater than 1 centimeter in size could be missed on a first colonoscopy," he noted. "Hidden behind a fold, hidden elsewhere. And if you miss a polyp the first time it has the potential to develop into cancer over three years, over five years. So, you can't minimize the importance of continued surveillance, even if this study shows that the benefit may be equivocal in the first 10 years."

Two other colon cancer studies -- both focused on elderly screening -- were presented Monday at the gastroenterology meeting.

Researchers with the University of Buffalo and the VA Western New York found that colonoscopies uncover polyps more frequently among patients over the age of 80 than among younger patients. They concluded that age alone should not be the sole deciding factor as to whether an elderly patient should undergo the procedure.

And a team at Scripps Clinic in La Jolla, Calif., found that colonoscopy seems to increase survival rates among the elderly by detecting polyps in patients as old as 84 who are without symptoms despite the onset of colorectal cancer.

More information

To learn more about screening for colorectal cancer, visit the American College of Gastroenterology  .