[Jackie07]

Didn't find one about breast cancer, but this abstract warned about Gastric cancer. However, I wondered if the pickled food that's been consumed by both the Japanese and the Korean people play an more important role.

Cancer Sci. 2011 Jan;102(1):231-44. doi: 10.1111/j.1349-7006.2010.01770.x. Epub 2010 Nov 10.
Fermented and non-fermented soy food consumption and gastric cancer in Japanese and Korean populations: a meta-analysis of observational studies.

Kim J, Kang M, Lee JS, Inoue M, Sasazuki S, Tsugane S.
Cancer Epidemiology Branch, Research Institute, National Cancer Center, Goyang, Korea. jskim@ncc.re.kr
Abstract

Soy food is known to contribute greatly to a reduction in the risk of gastric cancer (GC). However, both Japanese and Korean populations have high incidence rates of GC despite the consumption of a wide variety of soy foods. One primary reason is that they consume fermented rather than non-fermented soy foods. In order to assess the varying effects of fermented and non-fermented soy intake on GC risk in these populations, we conducted a meta-analysis of published reports. Twenty studies assessing the effect of the consumption of fermented soy food on GC risk were included, and 17 studies assessing the effect of the consumption of non-fermented soy food on GC risk were included. We found that a high intake of fermented soy foods was significantly associated with an increased risk of GC (odds ratio [OR] = 1.22, 95% confidence interval [CI] = 1.02-1.44, I(2) = 71.48), whereas an increased intake of non-fermented soy foods was significantly associated with a decreased risk of GC (overall summary OR = 0.64, 95% CI = 0.54-0.77, I(2) = 64.27). These findings show that a high level of consumption of non-fermented soy foods, rather than fermented soy foods, is important in reducing GC risk.