Organic foods are those cultivated without using any fertilizer or chemicals such as pesticides and herbicides.
The authors say, although organic foods are less likely to contain pesticide residues than conventional foods, few studies have examined the association of organic food consumption with cancer risk.
To arrive at the findings, Baudry and her colleagues analysed data from almost 69,000 people taking part in an ongoing French study of the associations between nutrition and health.
The study opens the door to many interesting questions, but it's not going to be the last word on whether organic foods matter for health, and cancer risk in particular.
"At the current stage of research, the relationship between organic food consumption and cancer risk is still unclear", the Harvard researchers wrote. The most common type was breast cancer (459 cases), followed by prostate cancer (180 cases), skin cancer (135 cases), colorectal cancer (99 cases), non-Hodgkin's lymphoma (47 cases) and other types of lymphomas (15 cases).
"Our findings revealed a negative association between high organic food scores and postmenopausal breast cancer, Non-Hodgkin Lymphoma, and all lymphomas".
"Because of their lower exposure to pesticide residues, it can be hypothesised that high organic food consumers may have a lower risk of developing cancer".
"We did expect to find a reduction, but the extent of the reduction is quite important", said Julia Baudry, the study's lead author.
And yet the authors do not put hard to equate the consumption of organic products and the prevention of cancer. Secondly, the completed questionnaires suggests that people prefer natural food, in General, were more healthy way of life: they had no bad habits and often played sports.
In an audio interview, Chavarro noted that one of the most compelling aspects of the study was study consistency with others' reported findings.
Individuals who are careful to pick organic foods may be more health conscious to begin with, living healthier lifestyles overall.
Those who ate more organic food were also more likely to have higher incomes, job status and education level.
"Assessing intake of diet is hard, assessing intake of organic foods is notoriously hard", said Chavarro.
They gave participants scores ranging from a low of 0, for no organic food consumption, to 32 for the highest consumption. "It's good to eat organic if you can because we know pesticides are carcinogens", Dr. Moline says.