BUT that study, the one that is most cited, was conducted in Marin County, the richest county in the US, located in northern CA, right next to wine country. It’s also got one of the highest rates of breast cancer in the country—so it should be no surprise that another study has examined why that might be (and it does not reference the previous study linking alcohol to breast cancer, but keep that in mind).
The new study examined the DNA of those living in Marin Country, and found that they were more likely to have a defunct gene relating to Vitamin D. Not having enough Vitamin D can also increase your risk for cancer and other health problems—but how the correlation comes about, and what the actual causation of breast cancer is in these women remains in doubt.
Both studies could be accurate, coming together to increase the breast cancer rate in this region, but cancer is so nebulous, with so many origins, that this is a reminder not to hold on to correlation to tightly, and how it may take years to fully sort out where cancer comes from (although we continue to make great strides in treating it!).
What do you think? Are both studies valid, neither? Is the new study, which focuses on DNA vs. (self-reported) environmental factors, more legitimate?