Data Clearly Links Soda Consumption to Pancreatic Cancer
Key Findings
Drinking two or more sodas a week almost doubles a person’s risk of developing pancreatic cancer. Following these people for 14 years yielded 648,387 person-years of data and 140 cases of pancreatic cancer (PC). Individuals who consumed 2 or more soft drinks a week experienced a statistically significant increase in risk of pancreatic cancer (hazard ratio, 1.87; 95% confidence interval, 1.10–3.15) compared with individuals who did not consume soft drinks. There was no association seen between drinking fruit juice and risk of PC.
Practice implications
This is just the latest in a series of studies on the subject that have yielded sometimes conflicting and confusing results. Yet the bottom line consensus appears to be that soda or other concentrated forms of sugar, such as candy bars, do increase risk of pancreatic cancer.
Pancreatic cancer does not respond well to treatment: 5-year survival even with modern treatment is less than 5%. Therefore, prevention is the best approach. Cigarette smoking is the one accepted risk factor consistently associated with increased risk of pancreatic cancer. Type 2 diabetes also increases risk, which led to a theory that producing high levels of insulin might somehow lead to malignant transformation of pancreatic cells.
In most cancers, the cells that become cancerous have been somehow overworked, irritated, or in some way abused before becoming cancer cells. They have been pushed by something to grow faster, work harder, secrete more or in some manner live harder lives. Estrogen pushes both breast and uterine cells to become cancerous. Testosterone pushes prostate cells to become prostate cancer. Infections push lymph cells to become lymphoma. This theory about pancreatic cancer suggests that high sugar intake pushes the pancreas.
Diabetes has been associated with pancreatic cancer for decades. A study on Seventh Day Adventists published in 1988 reported that “prior history of diabetes was associated with increased risk of subsequent fatal pancreas cancer.”1
A Kaiser Permanente study published that same year found that while cigarette smoking increased risk of pancreatic cancer by a factor of 2.5, people who had been treated for diabetes had 4.5 times the risk. (Smoking: relative risk, 2.5; 95% confidence interval, 1.3–4.7. Diabetes: relative risk, 4.5; 95% confidence interval, 1.2–16.7)2
A Dutch paper published in 1990 that analyzed data on 164 patients with pancreatic cancer found “a significant, positive association between pancreatic cancer and past habitual intake of simple sugars.” (OR 1.95; 95% confidence interval, 1.24–3.07). This led the study authors to suggest that “the development of exocrine pancreatic carcinoma is positively related to past habitual intake of total energy, total carbohydrates, and simple sugars.”3
A 1991 Australian paper that analyzed the habits of 104 people who developed PC also found a link to sugar consumption. “For the top quartile of refined sugar intake, the estimated relative risk was 2.21 (95% confidence interval, 1.07–4.55).”4
A December 1995 study that looked at 179 cases of PC in French speaking Canadians found a similar effect of sugar consumption. Again, high sugar consumption nearly tripled risk. Of interest in this paper was the pronounced effect of cooking with firewood, a habit that increased relative risk by a factor of almost 5, while cooking in a pressure cooker lowered risk to one-third the average.5
Sweetened carbonated drinks, what we call soft drinks, or soda, are a major source of simple sugars in western diets. As such, soda consumption provides a measure of overall sugar consumption.6 Soda consumption is associated with hyperglycemia and hyperinsulinemia, obesity, and type 2 diabetes.
Rates of developing pancreatic cancer have plateaued and are stable in the United States, but they are rising among Chinese men and women in Singapore. From 1968 to 1998, they have almost doubled (going from 3.7 to 5.4 per 100,000 for men and 1.5 to 3.4 per 100,000 for women). One explanation for this increase is the shift toward a more western diet and increased consumption of sugar and sugar-sweetened sodas. It may be that during this transition period between traditional diets and western diets, the effect of soda consumption is more pronounced. Soda may be adopted into the diet while traditional foods and recipes still comprise the basic diet.