WEDNESDAY, March 26 (HealthDay News) -- Keeping in good shape is more difficult for older women than men because it's harder for women to replace muscle that's lost naturally as they age, say U.S. and British researchers.

The study of 29 healthy women and men, aged 65 to 80, found that women were less able to use protein to build muscle mass -- a key difference in the way women's and men's bodies react to food. This may be due to menopause-related hormone changes in women, said the researchers from the Washington University School of Medicine in St. Louis and The University of Nottingham. One possible culprit is estrogen, which is known to be needed to maintain bone mass.

The findings, published in the current issue of the Public Library of Science One, seem to fit with preliminary results showing that older women have less muscle-building response to weight training than older men. This difference is not apparent in younger women and men.

"Nobody has ever discovered any mechanistic differences between men and women in muscle loss before. This is a significant finding for the maintenance of better health in old age," and reducing demand on health-care systems, Michael Rennie, a professor of clinical physiology at the University of Nottingham, said in a prepared statement.

The findings of this new study show that it's important for older women to consume plenty of protein-rich foods such as eggs, fish, chicken and lean red meat and to do resistance training (lifting weights in a gym), the researchers said.

"Rather than eating more, older people should focus on eating a higher proportion of protein in their everyday diet. In conjunction with resistance exercise, this should help to reduce the loss of muscle mass over time. There is also a case for the beneficial hormonal effect of limited HRT (hormone replacement therapy), although this has to be balanced against the other risks associated with such treatment," Rennie said.

The researchers noted that maintaining muscle is essential in reducing the risk of falls, one of the major causes of premature death in older adults. After age 50, people lose up to 0.4 percent of muscle mass per year.

Women are at particular risk for muscle mass decline, because they tend to have less muscle and more fat than men in early and middle age, which means they're already closer to the "danger" threshold of becoming frail when they're in their 50s and 60s, the researchers said.

More information

The U.S. Centers for Disease Control and Prevention has more about healthy aging for older adults.

TUESDAY, March 25 (HealthDay News) -- European researchers report more grim news concerning women and hormone replacement therapy: Not only do healthy women run the risk of developing breast cancer while taking the therapy, breast cancer survivors who do the same face a higher risk of a recurrence or a new malignancy.

"This is the first study where patients with relatively recent breast cancer were randomized to take either hormone therapy or to do alternative therapies," said Dr. Jennifer Wu, an obstetrician/gynecologist with Lenox Hill Hospital in New York City. "Really, at this point, there's no guarantee of the safety of hormone replacement therapy in breast cancer survivors. Some forms of estrogen and progestin and different regimens of those two may be safer, but the risks are pretty clear-cut."

The study, conducted by researchers from King's College London and Scandinavia, is published in the March 25 online issue of the Journal of the National Cancer Institute.

Several studies have pointed to an increased risk of breast cancer in healthy women taking hormone replacement therapy (HRT) for menopausal symptoms, but the evidence on breast cancer survivors has been limited.

"Previously, there were basically case studies, observational studies, and it looks like our data was a little bit biased," Wu said. "People who had been chosen to go on HRT probably were people who were years out from their diagnosis, who didn't have [estrogen receptor]-positive nodes, who had been doing very well."

This new trial was originally designed to see if HRT was safe to counter menopausal symptoms in women who had already had breast cancer. Women were randomly chosen to receive either hormone therapy or alternative methods of managing menopausal symptoms.

The researchers halted the trial early when it appeared that women taking HRT had a higher risk of breast cancer recurrence.

The current data, which represents a median of about four years of follow-up in 442 women, showed a 17.6 percent risk of a recurrence or a new tumor in the HRT group, compared with a 7.7 percent risk among women in the control group. The estimated five-year risk for a recurrence was 22.2 percent for women in the HRT group and 9.5 percent in the control arm, translating into a 14.2 percent absolute increased risk for women taking hormones.

Women in the trial had both estrogen receptor-positive and estrogen receptor-negative cancers. Estrogen receptor-positive cancer is fueled by the hormone estrogen.

The study did not determine if taking HRT increases the risk of dying from breast cancer.

For women in general, the message remains the same: They should avoid taking hormone therapy unless needed for severe menopausal symptoms, and then at the lowest dose possible for the shortest amount of time.

"For breast cancer survivors, the stakes are higher," said Debbie Saslow, director of breast and gynecologic cancer at the American Cancer Society. "My guess is that women survivors who would even consider HRT would be those with the best prognosis and severe menopausal symptoms. It's not recommended, but for some women that quality of life is important. You need to keep it all in perspective."

More information

Visit the U.S. National Cancer Institute for more on breast cancer.

TUESDAY, March 25 (HealthDay News) -- A new study confirms previous findings that human papillomavirus (HPV) DNA-based tests are more accurate than Pap smears in detecting precancerous lesions.

It was already known that the HPV test uncovered more infections and precancerous lesions than Pap smears (cytology), but it wasn't clear whether HPV tests would lead to the treatment of patients whose immune systems would fight off infections -- meaning that these women didn't require treatment, anyway.

In this study of almost 50,000 women, Italian researchers found that the HPV test identified almost twice as many premalignant lesions compared to Pap smears. Among women ages 35 to 60, the HPV test was more likely to detect cervical lesions. In women ages 25 to 34, the HPV test seemed to identify more infections that eventually resolved themselves.

Based on their findings, the researchers said it may be best for younger women with a positive HPV test to be retested in 12 months, rather than being immediately referred for a more intensive examination called colposcopy.

"It seems clear that an HPV DNA-based approach to primary screening is a very attractive option that should be actively developed and evaluated," wrote Dr. Guglielmo Ronco, from CPO Piemonte, in Torino, Italy, and colleagues.

The findings of this study, which were published in the Journal of the National Cancer Institute, reinforced similar findings in a study published in 2006 by Ronco and team.

That earlier study of 33,364 women, ages 35 to 60, found that HPV testing combined with liquid-based Pap testing detected 47 percent more precancerous lesions than conventional Pap smears. However, the combination testing increased the chance of false positives by 60 percent.

HPV accounts for almost all cases of cervical cancer.

More information

The U.S. National Women's Health Information Center has more about cervical cancer.

MONDAY, March 24 (HealthDay News) -- A new review of 32 studies suggests that obese women -- particularly white women -- are more likely than others to skip screenings for breast and cervical cancer.

No one knows why extra pounds heighten the likelihood that women will avoid mammograms or Pap smears. And it's not known why obesity seems to have no significant effect on colorectal screening, the researchers said.

However, the findings do point to a problem that deserves attention in the doctor's office, said study lead author Sarah S. Cohen, a graduate student in the department of epidemiology at the University of North Carolina at Chapel Hill.

"Because obesity is becoming an increasing problem in our health-care system, encouraging women who are overweight and obese to be screened may be especially important," she said. "It's important for physicians to address it and encourage women to be screened."

According to Cohen, the screening rates for breast and cervical cancer are fairly high. About 75 percent of American women receive mammograms every year or two after the age of 40, she said, while about 85 percent of women get Pap smears to test for cervical cancer.

The screening rates for colorectal cancer are much lower, perhaps around a third of women, she said.

The new review, published in the May 1 issue of the journal Cancer, examined 32 studies looking at breast cancer (10 studies), cervical cancer (14) and colorectal cancer (eight studies). The studies typically defined obese women as those having a body mass index [BMI, a ratio of weight to height] of 30 or above. That means they were more than merely overweight as defined by national guidelines.

Overall, obese women were 10 percent to 40 percent less likely to be screened for breast and cervical cancer compared to other women, Cohen said. Black women, however, seemed to be much less affected by obesity when it came to the screenings.

There are many theories why heavier women might be less likely to undergo health screenings, Cohen said. "It may be related to patients' emotional barriers, things like embarrassment and fear of being weighed. It may be provider-bias, physicians having a bias against obese patients. And [obese women] have other health-care needs, like dealing with high cholesterol."

Another possibility is that medical equipment may not be sized properly to accommodate larger patients, Cohen said. "None of this has been studied in any quantitative way," she added.

Dr. Massimo Cristofanilli, an associate professor in the department of breast medical oncology at the University of Texas M.D. Anderson Cancer Center in Houston, said another possibility was that "women with low-incomes choose high-caloric foods and have difficulty in being particularly careful with their lifestyle. They may also be largely uninsured and have minimal access to screening programs."

"We should recognize that prevention of obesity is a critical issue," Cristofanilli added. "Education about a healthy lifestyle should start at school and continue through media and in the family."

More information

To calculate your BMI, visit the U.S. National Heart, Lung, and Blood Institute  .