Dr. Jean-Pierre Chanoine and colleagues, from the British Columbia Children's Hospital in Vancouver, found that behavioral modification alone seldom led to sustained weight loss in obese adolescents, and say there is therefore a need for other strategies to promote weight loss.

The drug Xenical, known generically as Orlistat, produces weight loss by vastly reducing fat absorption in the intestines, it has a good safety profile and it is currently approved for use in obese and overweight adults.

In their research Chanoine's team assessed the weight-related outcomes of 539 obese teens who were randomly assigned to treatment with Orlistat or an inactive placebo. All the participants also followed a low-calorie diet, exercised, and got behavioral therapy for a year.

One hundred and seventeen subjects in the placebo group and 232 in the Orlistat group completed the study, but 180 and 348 subjects in the two groups, respectively, were included in the analysis.

Apparently both groups experienced a drop in body mass index (BMI - a measure of weight in relation to height) up to week 12, but after that point, the average BMI held steady in the Orlistat group whereas the BMI of the control group increased to levels higher than at the start of the study.

At one year, BMI had dropped by 0.55 in the Orlistat group, while it had increased by 0.31 in the control group.

The researchers say that the percentage of patients experiencing a reduction in BMI of at least 5 percent or 10 percent was significantly higher in the Orlistat group.

Gastrointestinal side effects, such as passage of fatty or oily stool and abdominal pain, were more common in the Orlistat group, but were usually mild.

Dr. Alain Joffe, from Johns Hopkins University in Baltimore, in an accompanying editorial, says the researchers "have made a valuable contribution" to the topic of adolescent obesity, but much more data are needed on the long-term benefits and risks of Orlistat therapy.

The research is published in the Journal of the American Medical Association, June 15, 2005.

Because it is hard for the sun to reach the underarm area, there was no difference in the underarm measurement between the prostate cancer cases and the control group, but when the forehead colour was compared to the underarm colour, the control group had significantly darker pigmentation than the cancer patients.

The team say increasing darkness was associated with a trend of decreasing risk of prostate cancer.

The scientists also obtained a sun exposure history from each participant so they could track outdoor activity and they found that a reduced risk of advanced prostate cancer was associated with high sun exposure determined by 'reflectometry and high occupational outdoor activity'.

They say further studies in large populations, including non-whites, are needed to confirm their findings.

According to the International Agency for Research on Cancer (IARC), the disease is the second most common cancer in men after lung cancer.

It was the most common form of cancer diagnosed among men in the European Union during 2004, representing 15 per cent of male cancers and 238,000 new cases, according to the IARC.

The study is published in the current issue of Cancer Research.