Although ultra-processed foods were linked to cancers in general, and breast cancer in particular, no association was found with prostate cancer or bowel cancer. It's already known that eating a lot of these foods can lead to weight gain, and being overweight or obese can also increase your risk of cancer, so it's hard to disentangle the effects of diet and weight.
The study underscored that the recently found link remained strong even after the research team adjusted the findings for other factors that may influence the outcomes.
But she added: 'They all have food additives, they all have compounds formed during the processing and heating of the products, and they have compounds that could come from the packaging itself.
What the scientists found was that a 10% increase in the proportion of ultra-processed foods in the diet was associated with a significant increase of greater than 10% in risks for overall cancer and breast cancer.
Ultra-processed foods may be associated with a higher risk of cancer.
"Although this research is intriguing and will add to existing evidence on how diet may impact breast cancer risk, it's far from conclusive".
"These results suggest that the rapidly increasing consumption of ultra-processed foods may drive an increasing burden of cancer in the next decades", the study concluded.
"It was quite surprising, the strength of the results".
"We don't want to be too alarmist", she says.
Ultra-processed foods make up between 25 to 50 percent of the average person's diet in several developed countries, the study said.
The nonprofit trade group Association of Food Industries did not respond to requests for comment.
The authors point out that the observational nature of the investigation means they can not say for certain that these types of processed food definitely cause cancer.
"This study doesn't mean that people should think 'if I eat this cracker, I'm going to get cancer, ' " McCullough said.
What should we take from this study? Nutritionists recommend a diet rich in whole grains, whole fruits and vegetables instead of foods that have little nutritional value.
Those snack cakes and chicken nuggets may be tasty, but they may also be upping your chances of cancer, according to a new study out of Sorbonne Paris Cite University.
Dr Touvier urged consumers to "apply the principle of precaution".
Sugary products were the most common form of ultra-processed food, making up 26 per cent of foods in this category.
The study, which appeared this week in the BMJ, suggests that foods like sweets that turn your tongue green and instant soups that are loaded with chemicals are cancer-causing. And the more of them an individual eats, the higher their risk of cancer of any type.
So, what counts as ultra-processed? "At least until we know more".