To the Editors: The recent article reporting no association of consumption of animal foods with risk of ovarian cancer (1) was based on an incomplete study (2). Whereas ecologic studies can find animal products as an important risk factor for breast cancer (2, 3), a more recent ecologic study based on ovarian cancer mortality rates for European countries for 1989 to 1991 and dietary data for the period 1974 to 1976 found that sugar is the most important dietary component (4). This study also found that ovarian cancer rates correlated directly with latitude, an index inversely correlated with solar UVB doses and vitamin D production, in a multiple linear regression analysis. A recent cohort study found high glycemic index and glycemic load to be important risk factors for ovarian cancer (5). Countries with high animal product consumption often have high sugar consumption as well, but it is easy to separate the two in ecologic studies. If the data for sugar consumption and/or glycemic load are readily available for the data set in ref. 1, it would be worthwhile to reprocess the data to check this link.

1
Schulz M, Nöthlings U, Allenet N, et al. No association of consumption of animal foods with risk of ovarian cancer.
Cancer Epidemiol Biomarkers Prev
2007
;
16
:
852
–5.
2
Parkin DM. Cancers of the breast, endometrium and ovary: geographic correlations.
Eur J Cancer Clin Oncol
1989
;
25
:
1917
–25.
3
Grant WB. An ecologic study of dietary and solar ultraviolet-B links to breast carcinoma mortality rates.
Cancer
2002
;
94
:
272
–81.
4
Grant WB. Ecologic studies of solar UV-B radiation and cancer mortality rates.
Recent Results Cancer Res
2003
;
164
:
371
–7.
5
Silvera SA, Jain M, Howe GR, Miller AB, Rohan TE. Glycaemic index, glycaemic load and ovarian cancer risk: a prospective cohort study. Public Health Nutr 2007;10.