A team at Yale University in the US found no link between fizzy drink consumption and a 350 per cent increase in cancer of the esophagus since the mid-1970s.
Their results also indicated that consumption of diet carbonated drinks was associated with reduced risk of this type of cancer, and that these drinks could have a protective effect that was "statistically significant".
The results provide a refreshing change for soft drink firms amid various public health concerns over their products.
Susan Mayne, lead author of the study and professor at Yale School of Medicine, said the new research was "the first direct test" of the theory that soft drinks caused esophageal cancer, despite media hype over the link.
The Yale team examined a study of 1,095 cancer patients and 687 control patients, conducted full dietary interviews and had access to available data on consumption of both regular and diet soft drinks.
"The researchers before us only put forth the hypothesis, but did not test that hypothesis by studying people with this cancer," said Mayne to www.BeverageDaily.com.
"They noted that consumption of carbonated beverages had gone up a lot, as had the incidence of this cancer (obviously this could be coincidence).
"However, they also noted that it was biologically plausible, so they suggested further evaluation of the proposed hypothesis. We did the evaluation and found no support for it."
Fizzy soft drinks have been linked with reflux actions in the lower esophagus, which are thought to be a risk factor for esophageal cancer.
"In fact, we observed a lower risk of this cancer for people who consumed carbonated soft drinks," said Mayne.
She added that the Yale team would welcome more research, despite having done the first dietary interviews on the issue. "We hope our report will stimulate others to try to replicate our findings."
The US National Soft Drink Association, now the American Beverage Association, unsurprisingly rubbished theories linking soft drinks and esophageal cancer in 2004. It said the correlation was meaningless and completely without foundation.
The soft drinks industry is by no means out of the woods, however. Regular soft drinks are still heavily linked to obesity, and one study released in November linked fizzy sodas to increased risk of hypertension, which can lead to heart disease.