TUESDAY, Aug. 4 (HealthDay News) -- Periodically cutting calories may lower the risk of developing breast cancer better than full-time dieting, according to a new study published in Cancer Prevention Research.

Three sets of mice predisposed to developing breast tumors were put on different diets: unlimited eating, intermittently cutting calories by 25 percent, or permanently reducing caloric intake 25 percent. Those on the intermittent diet fared best, with only 9 percent developing mammary tumors compared to 35 percent of those chronically restricted and 71 percent of those that ate all they wanted.

Although previous studies had shown similar results, the researchers were still surprised. Study author Margot P. Cleary, a professor at The Hormel Institute of the University of Minnesota, said her team thought periodic dieting might foster tumor growth as the return of added nourishment could jumpstart the secretion of insulin-like growth factor 1 (IGF-1), a hormone linked to the promotion of breast cancer.

"Understanding how calorie restriction provides protection against the development of mammary tumors should help us identify pathways that could be targeted for chemoprevention studies," she said in a news release. "Further identification of serum factors that are involved in tumor development would possibly provide a way to identify at-risk individuals and target interventions to these people."

This study "contributes to accumulating evidence that caloric restriction acts by altering hormone levels rather than by directly starving cancers of energy," Dr. Michael Pollak, a professor of oncology at McGill University in Montreal, wrote in an accompanying editorial. "In particular, lower levels of insulin are associated with reduced food intake, and this may be protective," he said.

Finding ways to reduce IGF-1 and insulin in the body, medically or though diet and exercise, should be further investigated, Pollak suggested.

More information

The National Cancer Institute has more about breast cancer.

THURSDAY, July 30 (HealthDay News) -- Women who are prone to the common vaginal infection, bacterial vaginosis, are less likely to have a recurrence if they take hormonal contraception, whether it be birth control pills or Depo-Provera injections, new research suggests.

In the study, researchers examined medical records for 330 women with a mean age of nearly 25 who visited two sexually transmitted disease clinics in Baltimore between April 2005 and October 2006. About 133, or 40.3 percent, were diagnosed with bacterial vaginosis.

The women were prescribed a contraceptive, either progestin only (such as Depo-Provera) or estrogen-progestin combination (a birth control pill).

Women who were taking an oral contraceptive that included estrogen and progestin were 34 percent less likely to have a recurrence of bacterial vaginosis than women not taking a contraceptive. Women who were on a progestin-only contraceptive were 58 percent less likely to have a recurrence, the researchers found.

Though the reduction attributed to the combined pill was not statistically significant, "it's fair to say a benefit is suggested," said senior study author Dr. Emily Erbelding, an associate professor of medicine at Johns Hopkins Bayview Medical Center.

The study appears in the July issue of Contraception: An International Reproductive Health Journal.

The study authors said they would not recommend that women who are prone to bacterial vaginosis start taking birth control for the sole purpose of warding off bacterial vaginosis.

"If you have other reasons for choosing birth control, it could be an added benefit," Erbelding said.

Dr. Jennifer Wu, an obstetrician-gynecologist at Lenox Hill Hospital in New York City, called the findings "encouraging."

"It supports that birth control pills possibly have additional advantages that can be used for treating bacterial vaginosis," Wu said.

Bacterial vaginosis occurs when the normal bacterial flora of the vagina is disrupted and replaced by an overproduction of other types of bacteria. Symptoms include a fishy odor and discharge, as well as itching, burning or pain. Women can also have bacterial vaginosis without symptoms.

It's the most common vaginal infection in women of childbearing age and is associated with preterm delivery and low birth weight babies, according to the U.S. Centers for Disease Control and Prevention.

Though treatable by antibiotics, bacterial vaginosis tends to recur, Erbelding said.

Previous research has shown that 15 percent to 30 percent of women have symptomatic bacterial vaginosis within three months after taking antibiotics, and 70 percent have a recurrence within nine months.

"As a clinician, we are always frustrated by the fact that our treatments aren't very good," Erbelding said. "They may ameliorate the symptoms for some time, but often bacterial vaginosis recurs."

Racial minorities are at greater risk of bacterial vaginosis, Erbelding said. In the study, about 82 percent of participants were black and 69 percent had been diagnosed with bacterial vaginosis before.

Bacterial vaginosis is also associated with sexual activity, douching and sexually transmitted diseases, including chlamydia, gonorrhea, herpes simplex virus and HIV.

Researchers aren't sure if bacterial vaginosis makes a woman more susceptible to the other infections or if the other infections make vaginosis more likely, Erbelding said.

"Nobody really knows which comes first," Erbelding said.

Hormonal contraceptives may help ward off a recurrence by altering the vaginal ecology or by reducing menstruation, which is also associated with changes to vaginal bacteria levels, according to the study.

More information

The U.S. Centers for Disease Control and Prevention has more on bacterial vaginosis.

FRIDAY, July 24 (HealthDay News) -- New moms who can't zip up their pre-pregnancy jeans might not be catching enough zzzs.

Getting a good night's sleep, in fact, may be just as important as diet and exercise for shedding baby weight.

One study of new mothers found that those who slept five or fewer hours a day six months after giving birth were three times as likely to hold onto those extra pounds as were women who got seven or more hours of sleep.

Short sleep duration "stood out as an independent risk factor" for weight retention, said Erica P. Gunderson, a research scientist and epidemiologist at Kaiser Permanente in Oakland, Calif., who worked on the study.

For many women, postpartum weight retention is a serious issue because it can lead to long-term weight gain. Some studies show that up to 20 percent of women retain at least 11 pounds at six to 18 months after giving birth, Finnish researchers reported.

Lifestyle factors that lead to postpartum weight retention -- including a woman's diet, physical activity and sleep patterns -- have not been well studied, researchers report. But as every bleary-eyed new mother knows, slumber is frequently disrupted or cut short in the first year after a baby's birth.

"Sleep deprivation can cause changes in the levels of hormones involved in appetite regulation," explained Dr. Sirimon Reutrakul, a clinical associate in medicine at the University of Chicago Medical Center.

"Keep in mind, though, that there are multiple factors involved in causing postpartum women to sleep less," she said. "These include just having a newborn, having other small children at home, possible postpartum depression, illness of the newborns, if any, work, etcetera," she said.

In Gunderson's study, the sleep and weight retention patterns of 940 Massachusetts women were analyzed. A year after giving birth, 124 of the women had retained 11 or more of the pounds they had put on during their pregnancy.

Short sleep duration was associated with a threefold higher risk of substantial weight retention, when compared with women who got seven hours of sleep. How long a woman breast-fed, however, was not a significant factor.

Dr. Truls Ostbye, a professor and vice chairman of research in the Department of Community and Family Medicine at Duke University Medical Center, is currently leading a study designed to promote weight loss in overweight women after childbirth. Preliminary data from that study show that "women who sleep less at six weeks lose less weight from six weeks to 12 months," Ostbye said.

But the relationship between sleep and weight loss isn't that simple. After adjusting for the fact that heavier women lose less weight and sleep less, "the effect of sleep on weight loss nearly goes away," he said.

"The relationship between obesity and sleep is there," he added, "but it is as likely that less sleep is a result of obesity as the other way around."

Advising women to get more sleep may not get to the root of their sleep-deprivation problem, Reutrakul said, "although stressing the importance of a good night's sleep is a good idea."

More information

The American Academy of Sleep Medicine has more about sleep and pregnancy  .

THURSDAY, July 9 (HealthDay News) -- Among women with ovarian cancer, those who had their first menstrual period before the age of 12 and who had the most menstrual cycles over a lifetime are more likely to die of the cancer than those who had fewer ovulatory cycles, a new study shows.

U.S. researchers analyzed data on 410 women, aged 20 to 54, who had ovarian cancer and were enrolled in the Cancer and Steroid Hormone (CASH) study between 1980 and 1982.

Using data that included in-depth patient interviews, reproductive history, contraceptive use and personal and family medical history, the researchers divided the women into groups based on their total number of ovulatory cycles.

There were 212 deaths among the participants during a median follow-up of 9.2 years, the study authors noted.

Women in the group who had the highest number of lifetime ovulatory cycles had a 67 percent greater chance of dying during the study follow-up, which ranged up to about 17 years.

The findings were independent of a woman's age at the time of the study, which would of course have a significant impact on the number of menstrual cycles a woman had had, said study author Cheryl Robbins, an epidemiologist at the U.S. Centers for Disease Control and Prevention.

Ovarian cancer patients whose age at menarche, or first menstrual cycle, was younger than 12 were 51 percent more likely to die from the cancer than those whose age at menarche was 14 or older, according to the study, published in the July issue of Cancer Epidemiology, Biomarkers & Prevention.

Ovarian cancer is the fifth-leading cause of cancer deaths among women. The high mortality is due, in part, because the disease is typically discovered after it has spread. Only about one-fifth of ovarian cancers are detected when the cancer is still localized, the study authors noted.

Previous research has linked age at first menstrual period and number of lifetime menstrual cycles with the risk of ovarian cancer, while use of oral contraceptives and hysterectomy or tubal ligation, which halt ovulation, have also been shown to reduce the risk of developing ovarian cancer.

Other studies have also found that having children earlier in life, having multiple children and breast-feeding provide protection, but the results are inconsistent, the researchers noted.

But less is known about the impact of those hormonal and reproductive factors on survival rates for women who already have the cancer.

"Although we have relatively good knowledge about the influence of reproductive factors on the risk of developing ovarian cancer, knowledge is rather limited regarding the reproductive factors that may influence survival after diagnosis with this serious disease," Robbins said.

Though the exact mechanism isn't understood, researchers believe that the surge of hormones brought on by ovulation, or the insult to the cells that occurs during ovulation, may be associated with more aggressive tumors, Robbins said.

In the current study, while age at first period and total lifetime menstrual cycles impacted survival, other factors, including number of pregnancies, breast-feeding and menopausal status did not show a statistically significant impact on survival rates.

Dr. Mary B. Daly, director of the Personalized Cancer Risk Assessment Program at the Fox Chase Cancer Center in Philadelphia, said the results shed more light on the role reproductive hormones play in ovarian cancer, potentially providing clues for developing new treatments for aggressive cancers.

Yet the study has its limitations, Daly added. Women's recollections could have been flawed, and the study participants were younger than the typical ovarian cancer patient and so may not be truly representative. Additionally, the women in the study had ovarian cancer nearly 30 years ago and would not have been receiving today's more advanced chemotherapy treatments.

Nor is the research definitive enough to suggest that women should go out and start taking contraceptive pills or having babies earlier to increase their chances of surviving ovarian cancer.

"The paper may suggest other avenues of research into what is it about the hormonal profile of women that could affect the biology of their ovarian cancer," Daly said. "As of right now, it doesn't translate into something you could clinically do differently."

More information

The U.S. National Cancer Institute has more on ovarian cancer.