Diet Soft Drinks and Improved Colon Cancer Outcome?

Roxanne Nelson, BSN, RN

July 23, 2018

Could drinking artificially sweetened soft drinks help reduce the risk for cancer recurrence and death in patients with advanced colon cancer?

New findings from a large clinical trial suggest that patients with stage III colon cancer who said they drank one or more 12-oz servings of an artificially sweetened beverage each day had a 46% reduction in the risk for death or recurrence when compared to similar patients who did not consume these drinks.

However, lead author Charles Fuchs, MD, director of the Yale Cancer Center at Yale University in New Haven, Connecticut, cautioned that this might be largely due to a "substitution effect."

"It may be that substituting artificially sweetened sodas for sugar-sweetened ones is driving the effect," Fuchs told Medscape Medical News. "We don't have an alternative explanation at the moment as to why artificially sweetened sodas would improve outcomes."

The study was published online July 19 in PLOS ONE.

There has been some concern that artificial sweeteners could negatively affect health. Some data suggest that the consumption of artificial sweeteners increases the incidence of obesity, diabetes, cancer, and other health problems. Experimental studies have generally suggested that substituting artificially sweetened drinks for sugar-sweetened beverages reduces energy excess, but large observational studies have produced contradictory findings. Fuchs explained that some of the associations seen in observational studies may be due in part to reverse causality. "The people in those studies are at a high risk of weight gain or are overweight, so they may be choosing the artificially sweetened drinks in an attempt to lose weight," he said.

As previously reported, consumption of sugar-sweetened beverages has been linked to a higher risk for obesity, type 2 diabetes, and related cardiometabolic disease, as well as a higher risk for disease recurrence and mortality in patients with stage III colon cancer.

"We have found that maintaining a healthy weight, regular exercise, and not eating a high glycemic diet significantly improved outcomes," said Fuchs. "And drinking sugar-sweetened drinks worsened outcomes. So we wanted to see if consuming artificially sweetened drinks would have any effect."

This is the first study of artificially sweetened beverage intake and colon cancer recurrence and survival. Fuchs noted that they "at least hoped to find a neutral effect. But instead, there was a clear benefit," he added.

Reduced Mortality and Recurrence

The participants in the current trial were part of the CALGB 89803 trial (run by the Cancer and Leukemia Group B [CALGB], which is now part of the Alliance for Clinical Trials in Oncology). This trial investigated adjuvant therapy for stage III colon cancer and enrolled 1264 patients.

All patients completed a self-administered questionnaire about diet and lifestyle habits midway through their therapy (4 months after surgery) and then 6 months after the completion of treatment (14 months after surgery).

A number of embedded studies were designed to find associations between specific dietary factors and colon cancer risk and death.

A previous report from this same trial and questionnaire found that patients who consumed tree nuts had a substantially reduced risk for cancer recurrence and death. Another study linked consumption of sugar-sweetened beverages with the risk for colon cancer recurrence and mortality.

This study on artificially sweetened beverages involved a cohort of 1018 patients. At a median follow-up time of 7.3 years, 348 patients experienced colon cancer recurrence or developed new primary tumors; of these patients, 265 died.

After adjusting for other predictors of disease recurrence, the researchers found that increasing intake of artificially sweetened beverages was associated with a significantly lower risk for cancer recurrence or mortality. For patients who consumed two or more 12-oz servings per day, the adjusted hazard ratio (HR) for disease recurrence or mortality was 0.58 (95% confidence interval [CI], 0.31 - 1.07; P for trend, .004) in comparison with those who largely abstained from such drinks.

An increased intake of artificially sweetened beverages was also associated with a significant improvement in both relapse-free survival (P for trend = .005) and overall survival (P for trend = .02). These findings remained largely unchanged after adjusting for different dietary patterns.

To estimate the influence of substituting artificially sweetened beverages for sugar-sweetened beverages on outcomes, Fuchs and his colleagues conducted a substitution analysis.

They found that replacing one 12-oz serving of a sugar-sweetened beverage per day with an isovolumetric serving of an artificially sweetened beverage was associated with a significant improvement in outcomes: 23% for disease-free survival (HR, 0.77; 95% CI, 0.63 - 0.95; P = .02), 26% for relapse-free survival (HR, 0.74; 95% CI, 0.59 - 0.93; P = .01), and 22% for overall survival (HR, 0.78; 95% CI, 0.62 - 0.99; P = .04).

Fuchs explained that, on the basis of these findings, it would be reasonable for physicians to suggest to patients who drink sugar-sweetened soft drinks that they switch to diet sodas. "These drinks may help satisfy that craving for a sweet drink, and our results suggest that it is a better alternative," he said.

Experts Weigh In

Benjamin Weinberg, MD, assistant professor of medicine, the Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, noted that there is not enough evidence to justify telling patients who have undergone colon cancer resection to consume artificially sweetened beverages daily.

"To definitively answer this question, you would have to prospectively randomize these patients to artificially sweetened beverage consumption or not, and then follow them for disease recurrence and death," he said. "There are a number of confounders, because these consumers are likely a different patient population than those who don't consume them."

However, Weinberg pointed out that the data also suggest that there were not significant interactions between factors that are known to decrease disease recurrence, such as exercise, taking aspirin, and possibly drinking coffee, and whether patients consume these drinks or not.

He agreed with Fuchs in that the "effect we may be seeing is that it is the lack of consumption of sugary drinks that's driving this benefit rather than the proactive consumption of nonsugary drinks.

"So, I think in this case sugar is probably bad but may select for a less healthier group of patients who are more likely to consume sugar," Weinberg added.

Daniel Labow, MD, chief of the Division of Surgical Oncology, the Mount Sinai Health System, New York City, also feels that eliminating sugar may be responsible for the effect.

"I think it is basically an association, because the patients who are not drinking sugary sodas are more conscious of their health and intake," said Labow. "I don't think diet soda prevents colon cancer."

The study was supported by the National Cancer Institute of the National Institutes of Health. Dr Fuchs has had a consulting or advisory role with Lilly, Sanofi, Bayer, Merck, Entrinsic Health, Five Prime Therapeutics, Agios, Gilead Sciences, Dicerna, Merrimack, Taiho Pharmaceutical, KEW Group, and Genentech/Roche; several coauthors have disclosed relationships with industry. Dr Labow has disclosed no relevant financial relationships.

PLoS ONE. Published online July 19, 2018. Full text


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