FRIDAY, Oct. 5 (HealthDay News) -- New research on anal cancer, a rare disease that's often caused by a sexually transmitted virus, found that nearly one-third of men with this form of cancer were HIV-positive.

Men infected with HIV, the virus that causes AIDS, are more likely to also become infected with the human papillomavirus (HPV), which can cause both cervical and anal cancer.

The findings, published Oct. 5 in the Journal of the National Cancer Institute, point to the importance of screening HIV-positive men for anal cancer, said study co-author Dr. Eric Engels, a senior investigator with the U.S. National Cancer Institute. "In the United States, fewer than 1 percent of people have HIV infection. Yet when you look at anal cancer, 28 percent of all cases in men are in those who have HIV."

According to background information in the study, anal cancer is diagnosed in about 6,000 people a year in the United States, mostly women, and kills around 700. Early detection, however, can lower the risk of death.

The anal cancer rate has been rising in the United States since 1940, the study authors pointed out, and several groups -- gay men, those with multiple sexual partners over their lifetime, those who've had genital warts, and those who have anal intercourse -- are at highest risk.

In the new study, researchers examined medical records from several states from 1980 to 2005 and found, over the entire period, that an estimated 8 percent of 20,533 anal cancer patients were infected with HIV. From 2001 to 2005, they estimated that 1 percent of women and 28 percent of men with anal cancer were HIV-positive.

The study suggests that there's a link between HPV and HIV infection. HPV is estimated to cause about 85 percent of anal cancer cases, Engels said. The virus can cause cells to make genetic changes and become cancerous.

HPV is transmitted through skin-to-skin contact, such as sexual activity. But people don't need to be on the receiving end of anal sex to develop an infection in the anal area. A person could transmit the virus from another part of the body, such as the genitals, to the anus, Engels explained.

What to do? There is no treatment or cure for HPV, according to the U.S. Centers for Disease Control and Prevention. However, "if one could prevent anal cancer in men with HPV, it would have a noticeable impact on the overall national burden of anal cancer," Engels said.

One way to do that is to use Pap tests -- which detect cervical cancer in women -- to screen HIV-infected people for anal cancer. "There is debate about whether that will be an effective approach," he said. "It's something that's being looked at."

Another strategy is to give people the vaccine series that prevents HPV infection. Young women and girls are frequently vaccinated because HPV can lead to genital warts and cervical cancer, but the vaccination is not as common among young men and boys.

However, Engels said, "there haven't been definitive studies in people with HIV to know whether the HPV vaccine will prevent anal cancer."

Commenting on the study, Dr. Joel Palefsky, a professor of medicine at the University of California, San Francisco, said the findings make sense. He recommends anal cancer screening not only for HIV-positive gay men but for all gay men.

Anal Pap tests are appropriate for HIV-positive men and older gay men, although there aren't federal guidelines for gay men, and doctors may not get reimbursed for the procedures, Palefsky said. He also recommends that physicians perform so-called digital exams in the rectum to look for signs of anal cancer in gay men.

These examinations are commonly performed to look for signs of prostate cancer, but physicians may not focus on also detecting anal cancer, Palefsky added.

More information

For more about anal cancer, visit the U.S. National Library of Medicine.

THURSDAY, Oct. 4 (HealthDay News) -- Researchers who developed a mathematical model to help predict a couple's chances of becoming pregnant say the method may help determine how long couples should wait before seeking medical help to achieve pregnancy.

The method determines the probability of conception within the next month by using the number of menstrual cycles that have occurred during the time a couple has been trying to conceive.

For example, the U.K. researchers found that a 35-year-old woman who has been trying for six months to get pregnant has only a 10 percent chance of conceiving within the next month.

In comparison, the number of months required to reach a conception chance below 10 percent is 10 months at age 30 and 13 months at age 25, according to the study appearing online Oct. 4 in the journal PLoS One.

"Many couples are not aware that chance plays a big role in getting pregnant. People expect to get pregnant when they want to, so finding out that it isn't happening can be a shock. Approaching a doctor about such a personal matter is daunting, so knowing when is the right time to start investigations would be a useful step forward," study author Geraldine Hartshorne of Warwick Medical School, said in a University of Warwick news release.

"We can't work out exactly when, or if, a woman will become pregnant -- but this analysis can predict her chances, and give a percentage estimate of pregnancy in the next cycle," she added.

Common wisdom has been that couples who are trying to get pregnant should have regular sex for a year before seeking help, but this study shows that age also affects this decision.

"Comparatively few young couples have low fertility, and so for these couples, the most likely reason for failing to conceive in the first few cycles is simply bad luck. There is quite a good chance of conception if they keep trying," study author Peter Sozou, of the London School of Economics, said in the news release.

"But older couples are more likely to have low fertility, so it's more likely for them than for younger couples that failure to conceive after a few months is due to low fertility," he noted.

More information

The U.S. National Institute of Child Health and Human Development has more about infertility/fertility.

MONDAY, Oct. 1 (HealthDay News) -- The most common side effects in girls and young women who receive the human papillomavirus (HPV) vaccine appear to be fainting right after the injection and skin infections where the shot was given, a new study confirms.

The quadrivalent (HPV4) vaccine -- brand name Gardasil -- is given to girls aged 9 and up to protect them from cervical and other cancers caused by the virus. It has been used in the United States for six years.

"We did not detect any new safety concerns with this vaccine," said lead researcher Dr. Nicola Klein, of the Kaiser Permanente Vaccine Study Center in Oakland, Calif.

She noted that the team looked at many different possible side effects. "This is a very reassuring finding," she added.

Fainting on the same day as vaccination has been associated with other injections as well as Gardasil -- particularly among adolescents -- and skin infection is a concern with any injection, Klein said.

The report was published in the Oct. 1 online edition of the Archives of Pediatrics & Adolescent Medicine.

The study, funded by Merck & Co., the maker of the vaccine, was required by the U.S. Food and Drug Administration to determine which immediate side effects resulted from the vaccine.

Study participants were females aged 9 to 26 who received at least one of the three recommended doses of Gardasil between August 2006 and March 2008.

Among nearly 190,000 girls or young women vaccinated, only fainting on the day of vaccination and skin infections within the next two weeks were deemed likely to be associated with the vaccine.

"These findings support the general safety of routine vaccination with HPV4 to prevent cancer," the researchers said.

Although some of these skin infections may have been a local reaction where the injection was given, more girls sought care for a skin infection a while after the vaccination, the researchers noted.

HPV viruses are common types of sexually transmitted viruses. Although most cause no symptoms and go away on their own, genital HPV infection can cause cervical cancer, as well as other cancers and genital warts in both women and men. In June 2006, the FDA approved the HPV vaccine for girls and women aged 9 to 26, according to study background information, which noted that approval has since been expanded for males in that age group.

"This substantiates the belief we had about the HPV vaccine -- that it's a safe vaccine," said Dr. Elizabeth Poynor, a gynecologic oncologist and pelvic surgeon at Lenox Hill Hospital in New York City. Poynor was not involved with the study.

Poynor agreed fainting is not uncommon with other vaccines. "This is a potential side effect of any type of vaccination," she said.

Real-world experience with drugs and medical devices often differs from what was found in clinical trials, but now the safety of the HPV vaccine has been substantiated with real-world data, Poynor said.

"This is a vaccine all young women should consider," she said.

For more information on the HPV vaccine, visit the U.S. Centers for Disease Control and Prevention.