(This is an excerpt of the Health Rounds newsletter, where we present latest medical studies on Tuesdays and Thursdays.)
By Nancy Lapid
(Reuters) -In patients with melanoma or non-small cell lung cancer, consuming high levels of the artificial sweetener sucralose contributes to diminished responses to immunotherapy and poorer survival, researchers reported in Cancer Discovery.
When the researchers had 132 patients with advanced melanoma or non-small cell lung cancer answer detailed diet history questionnaires, they found that high consumption of sucralose was linked with lower effectiveness of immunotherapies across a range of cancer types, stages and treatment methods.
In experiments with mice, the researchers found that sucralose shifts the composition of microbes in the intestines, increasing bacterial species that degrade arginine, an amino acid that is essential for key immune cells called T cells.
“When arginine levels were depleted due to sucralose-driven shifts in the microbiome, T cells couldn’t function properly,” study leader Abby Overacre of the University of Pittsburgh said in a statement. “As a result, immunotherapy wasn’t as effective in mice that were fed sucralose.”
Laying the groundwork for a solution to the problem, the same researchers also found in the mice that supplements that boosted levels of arginine mitigated the negative effects of sucralose on immunotherapy, an approach they now hope to test in humans.
“It’s easy to say, ‘Stop drinking diet soda,’ but when patients are being treated for cancer, they are already dealing with enough, so asking them to drastically alter their diet may not be realistic,” Overacre said.
“That’s why it’s so exciting that arginine supplementation could be a simple approach to counteract the negative effects of sucralose on immunotherapy.”
LOW-GRADE IS NOT THE SAME AS LOW-RISK IN PROSTATE CANCER
A low-grade prostate tumor is not necessarily low-risk, new research suggests.
Biopsy results showing low-grade prostate cancers can sometimes lead to underestimation of disease risk and omission of surgery or radiation in patients who might benefit from such treatments, researchers warned in JAMA Oncology.
Among roughly 117,000 men in their study with prostate biopsy results indicating a Grade Group 1, or GG1, tumor – the slowest-growing kind – one in six had intermediate- or high-risk cancer when other factors such as prostate-specific antigen levels in the blood and tumor sizes were also considered, according to the report.
Such higher risk cancers are often treated with radiation therapy or removal of the prostate, the researchers noted.
“We don’t want to miss aggressive cancers that initially present as Grade Group 1 on biopsy,” study coauthor Dr. Bashir Al Hussein of Weill Cornell Medicine said in a statement. “Such underestimation of risk could lead to undertreatment and poor outcomes.”
Current guidelines that advise regular monitoring – rather than treatment – for men with low-grade prostate tumors were based on studies that examined entire prostate glands after removal from patients.
Biopsies test only small areas of the prostate, so they can miss more advanced or aggressive cancer cells, providing an incomplete picture, the researchers said.
Some cancer experts have been suggesting recently that GG1 tumors are so slow-growing that they shouldn’t even be considered malignant. The new study results could help inform those discussions, the researchers said.
“There is a misunderstanding that low grade and low risk are the same,” study coauthor Dr. Jonathan Shoag of Case Western Reserve University said in a statement. “Here, we show clearly that they are not.”
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(Reporting by Nancy Lapid; editing by Bill Berkrot)
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