(This is an excerpt of the Health Rounds newsletter, where we present latest medical studies on Tuesdays and Thursdays. To receive the full newsletter in your inbox for free sign up here)
By Nancy Lapid
(Reuters) - Cancer patients with dark skin are at higher risk for severe cases of a painful side effect of radiotherapy, at least partly because the tool for detecting the condition only works well in light-skinned patients, new research shows.
Of the four million U.S. patients who receive radiation therapy each year, more than 90% will develop burns known as radiation dermatitis. The primary screening tool approved by the National Cancer Institute for detecting and grading the severity of the condition looks for reddening of the skin.
For this study researchers screened for radiation dermatitis over the course of a year after the start of radiotherapy in 60 racially diverse breast cancer patients, using a device known as a spectrophotometer often used for color analysis in the paint and cosmetics industries.
Unlike light-colored skin, darker skin does not exhibit reddening as radiation dermatitis develops. Instead, it darkens, the new study found.
The same research team had previously reported that doctors often do not diagnose radiation dermatitis in patients with darker skin until the skin has begun to peel and scar.
That leaves patients treating their pain on their own, with over-the-counter creams and painkillers, said study leader Dr. Juhi Purswani of NYU Langone, who shared the new findings at the American Society for Radiation Oncology meeting in Washington.
The standard screening tool “likely under-captures radiation dermatitis in skin of color” and must be changed, the researchers concluded in a summary for the presentation.
For longer life, dieting 'success' may need rethinking
Traditional measures of dieting success, such as weight loss and improvements in metabolic issues, may not be the keys to longer life, laboratory experiments suggest.
Among nearly 1,000 mice subjected to periods of calorie restriction or intermittent fasting, those who lost the least amount of weight lived longer than those who lost the most, researchers reported in Nature.
The finding from "one of the biggest studies of dietary restrictions ever conducted in laboratory animals challenges the conventional wisdom about how dietary restriction boosts longevity," according to a commentary published with the report.
Overall, consuming fewer calories had a greater positive impact on lifespan than periodic fasting. But animals who lost the most weight on these diets tended to have low energy, compromised immune and reproductive systems, and shorter lives, the study found.
Moderate levels of calorie restriction might therefore be the way to balance long-term health and lifespan, the researchers said.
The factors most strongly associated with a longer lifespan included retention of body weight through periods of stress, strong immune cell health, traits related to red blood cells, and high body fat levels in late life.
Metabolic responses to dietary restriction, such as lower fasting blood sugar levels, were not associated with longer lifespan.
“The most robust animals keep their weight on even in the face of stress and caloric restriction, and they are the ones that live the longest,” study leader Gary Churchill of The Jackson Laboratory in Bar Harbor, Maine said in a statement.
The results show that genetics had a larger influence on lifespan than dietary restriction, the researches found.
“If you want to live a long time, there are things you can control within your lifetime such as diet, but really what you want is a very old grandmother,” Churchill said.
(Reporting by Nancy Lapid; editing by Bill Berkrot)
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