THURSDAY, May 8 (HealthDay News) -- While the rate at which breast cancer tumors grow varies among patients, that growth tends to be faster among younger women, Norwegian researchers report.

These findings may help in planning and evaluating screening programs, clinical trials and other studies, the researchers say.

Using a new mathematical model, the scientists were also able to estimate the numbers of breast cancers detectable by mammography. This is a new approach to estimating the growth rate of tumors and the ability of mammograms to find them.

"There are enormous implications for the sensitivity of breast cancer screening programs," lead researcher Harald Weedon-Fekjr, of the Department of Etiological Research, Cancer Registry of Norway, said in a statement.

"We found that mammography screen test sensitivity increases sharply with increased tumor size, as one might expect. Detection rates are just 26 percent for a 5 millimeter tumor but increase to 91 percent once a tumor is 10 millimeter in size," he added.

The report was published in the May 8 issue of the online journal Breast Cancer Research.

In the study, Weedon-Fekjr, and colleagues tested their model using mammography results from 395,188 women aged 50 to 69.

The researchers found that the growth rate of tumors varied significantly between patients. About one in 20 tumors doubled in size, from 10 to 20 millimeters in just over a month. However, a similar number of tumors took more than six years to double in size.

Based on this finding, Weedon-Fekjr's team estimated that it takes an average of 1.7 years for tumors to double in size. Moreover, tumor growth appeared to be faster among younger women and slowed as women aged, the researchers noted.

"Tumor growth and test sensitivity estimates can be directly linked to tumor size in a full population study, resulting in very useful growth estimates directly connected to a biologically relevant measure," the researchers wrote.

"Tumor growth seems to vary greatly between tumors, with higher growth rates among younger women. Most tumors become visible at screening when they reach a diameter of 5 millimeters to 10 millimeters," they concluded.

One expert thinks this study again confirms the need for women to have a mammogram every year.

"This study continues to prove why we need to screen women every year, starting at age 40," said Debbie Saslow, director of breast and gynecologic cancer at the American Cancer Society.

This is another study that shows that tumors grow faster in younger women, Saslow said. "It just doesn't make sense to have guidelines that say younger women should be screened every one to two years and every year as they get older," she said.

More information

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

WEDNESDAY, May 7 (HealthDay News) -- Women with high blood sugar levels during pregnancy face an increased risk of complications, even if the high blood sugar readings don't meet the criteria for gestational diabetes.

In a large, international study, researchers found that for each standard deviation increase in blood sugar, there was a greater risk of complications, such as having a large birth weight baby or needing a Caesarean section delivery.

"We found strong independent associations between a mother's blood sugar levels during an oral glucose tolerance test and 28 weeks of gestation and the pregnancy outcomes," said the study's lead author, Dr. Boyd Metzger, the Tom D. Spies professor of metabolism and nutrition at the Feinberg School of Medicine at Northwestern University in Chicago.

What this means for pregnant women right now, however, isn't clear.

"Because the relationship between the mother's blood glucose level and risk tend to be continuous and linear, it is not clear where the risk reaches the point where treatment should optimally begin," said Metzger.

"We were hoping there would be a breakpoint," explained another of the study's authors, Dr. Don Coustan, professor and chair of obstetrics and gynecology at the Warren Alpert Medical School of Brown University in Providence, R.I. "But, the relationship between glucose levels and outcomes were continuous, which means it will be difficult to decide where to put the 'treating' point."

Coustan added that there will be a conference in June where pregnancy and diabetes experts will likely debate the pros and cons of treating hyperglycemia. For now, he said, he suspects that "doctors will still use the glucose threshold they're currently using."

One thing that was clear from the study is that higher odds of complications, like an increased risk of C-section or a large baby, are related to high blood sugar and not to other conditions, such as obesity or older maternal age, according to Metzger.

Results of the study were published in the May 8 issue of the New England Journal of Medicine.

The study included more than 23,000 pregnant women from 15 centers in nine countries. None of the women had diabetes. All of the women underwent glucose tolerance testing between 24 and 32 weeks of gestation. This test is performed by first taking a fasting blood sugar reading, then having the woman drink a high-carbohydrate liquid -- in this case a 75-gram carbohydrate drink; 100 grams is standard in the United States -- and then rechecking blood sugar levels at one and two hours to assess how the body is processing the high sugar load.

The higher a woman's blood sugar levels were, the more likely she was to have a C-section, to develop preeclampsia, have premature delivery and to have the delivery complication known as shoulder dystocia, the study found.

Babies born to women with higher glucose levels were more likely to have high insulin levels, low blood sugar, and to have a large birth weight, all indications of exposure to high glucose levels.

The odds of these complications changed continuously as blood sugar levels rose. For example, a woman with the highest levels of blood sugar (but not diabetes) had large babies 26 percent of the time, compared to just 5 percent for women with the lowest blood sugar levels.

"Basically, what they found out is that there is no threshold where you know to treat. That makes it difficult to know what to do with these findings," said Dr. Joel Zonszein, director of the Clinical Diabetes Center at Montefiore Medical Center in New York City.

A second study in the same issue of the journal looked at the use of the oral diabetes medication metformin, versus insulin, the standard treatment for gestational diabetes. The study included 751 women, randomly assigned to receive metformin or insulin treatment.

The researchers found that metformin was well-tolerated, although almost 43 percent of the women eventually required the use of supplemental insulin. There were no serious adverse events reported for mother or baby from the use of metformin, according to the study.

Of this study, Zonszein said, "My guess is that until we have larger studies, there's not going to be a big change in recommendations, because we have so much experience with insulin." But, he added, many women and obstetricians may welcome these findings because "giving a pill is easier than giving insulin." He said another oral medication, glyburide, was also found effective in another small trial.

More information

To learn more about gestational diabetes, visit the American Diabetes Association  .

TUESDAY, May 6 (HealthDay News) -- New research shows that women who quit smoking have a 21 percent lower risk of dying from coronary heart disease within five years of extinguishing their last cigarette.

The risks of dying from other conditions also decline after quitting, although the time frame varies depending on the disease.

"The harms of smoking are reversible and can decline to the level of nonsmokers," said study author Stacey Kenfield, whose report is in the May 7 issue of the Journal of the American Medical Association. "For some conditions like chronic obstructive pulmonary disease, it can take more than 20 years, but there is a rapid reduction for others."

"It's never too early to stop, and it's never too late to stop," added Kenfield, who is a postdoctoral research fellow in the department of epidemiology at the Harvard School of Public Health in Boston.

Smoking is still the leading preventable cause of death in the United States. Not only does tobacco smoke cause lung cancer, it is also implicated in heart disease, other cancers and respiratory diseases.

According to the World Health Organization, an estimated 3 million people in industrialized countries will have died as a result of tobacco use by 2030, and an additional 7 million people in developing countries face the same fate.

This research is a continued follow-up on the Nurses' Health Study, a large trial involving more than 100,000 women. Scientists now have 22 years of data on the participants.

Current smokers had almost triple the risk of overall death compared with women who had never smoked.

Current smokers also had a 63 percent increased risk for colon cancer compared with never-smokers, while former smokers had a 23 percent increased risk. There was no significant association between smoking and ovarian cancer.

And women who started smoking earlier in life were at a higher risk for overall mortality, of dying from respiratory disease and from any smoking-related disease.

However, a smoker's overall risk of dying returned to the level of a never-smoker 20 years after quitting. The overall risk declined 13 percent within the first five years of abstaining.

Most of the excess risk of dying from coronary heart disease vanished within five years of quitting.

For chronic obstructive pulmonary disease, the return to normal took almost 20 years, although there was an 18 percent reduction in the risk of death seen within five to 10 years after quitting.

And the risk for lung cancer didn't return to normal for 30 years after quitting, although there was a 21 percent reduction in risk within the first five years compared with women who continued to smoke.

Many previous studies on tobacco use had focused on men and on lung cancer, the authors stated. They also only looked at smoking status at the beginning of the study. "We got smoking information every two years, so we feel we have a more accurate estimate of current and past smoking," Kenfield said. "We saw increased risks for current smokers [than previous studies], and we think that's because we know who the current smokers are."

"This shows the power of quitting smoking," said Dr. Jay Brooks, chairman of hematology/oncology at Ochsner Health System in Baton Rouge, La. "We've known this for a number of years, but the beauty of this study is it is a very large and well-studied group of people. When I tell people to quit smoking, I say the effect of the heart precedes that of the lungs. If you've smoked, you need to be cognizant that you're still at an increased risk of lung cancer."

More information

Visit the American Lung Association   for more on women and smoking.

TUESDAY, April 29 (HealthDay News) -- Screening for cervical cancer reduces the risk for all types of the disease in women of all ages, say Swedish researchers. They also concluded that better follow-up of women who have cervical cancer screening could lower rates of the disease.

The researchers reviewed data from the National Cervical Cancer Screening Registry on 1,230 cervical cancer patients diagnosed between 1999 and 2001, and 6,124 age-matched women who hadn't been diagnosed with cervical cancer.

Women who hadn't had a Pap smear screening test within the recommended three-year interval were 2.5 times more likely to be diagnosed with cervical cancer than women who had regular Pap tests. Women who didn't have regular screening were also nearly five times more likely to be diagnosed with advanced cervical cancer than those were had regular screening.

Regular screening reduced the risk for all types of cervical cancer and reduced the risk of women between ages 23 and 30, which were new findings, according to the researchers.

They noted that screening didn't completely protect women from cervical cancer. Women who were screened at the recommended interval and were found to have abnormal cells were 7.6 times more likely to develop cervical cancer than women who were screened and had normal results.

Women with abnormal Pap results accounted for 11.5 percent of all cervical cancer cases. This increased risk was not noted in women diagnosed with advanced cervical cancer.

The study was published online April 29 in the Journal of the National Cancer Institute.

The researchers said their findings show that irregular screening is the most important risk factor for incident cervical cancer and that abnormal smears, if not followed up by a biopsy, are also an important risk factor.

In an accompanying editorial, Jack Cuzick, of the Cancer Research UK Centre in London, emphasized the importance of systematic audits of cancer screening programs.

"Audits, such as the one described (in this study), need to become routine within screening programs if screening is to achieve its full potential," Cuzick wrote. These reviews identify areas of screening programs that are ineffective and need to be restructured and improved.

More information

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