That’s about all we know for sure, according to a report from an expert panel convened by the American Diabetes Association and the American Cancer Society and published recently in CA: A Cancer Journal for Clinicians.
The report is focused on type 2 diabetes simply because 95% of all worldwide cases of diabetes are type 2; we have much more data. [Type 1 diabetes, you may recall, has onset much earlier in life and is fatal if not treated with insulin injections. The type 1 pancreas produces no insulin.]
Does optimal treatment of diabetes reduce cancer risk? Do particular diabetic medications raise or lower the risk of cancer? If an overweight diabetic loses excess weight, does the risk of cancer diminish? Sorry, we don’t know.
In men, 25% of all invasive cancers in the U.S. will be prostate cancer. In women, breast cancer is the leader, comprising 26% of all cancers. [Common skin cancers are rarely invasive or fatal and are not included in these statistics. Melanoma, on the other hand, is invasive.]
The lifetime probability of an individual developing invasive cancer in the U.S. is about 4 in 10 (40%). A little higher in men (45%), a little lower in women (38%). The American Cancer Society projected 565,650 deaths from cancer in 2008. If we look at deaths of people under 85, cancer kills more people than heart disease.
The traditional Mediterranean diet is associated with lower risk of prostate, breast, colon, and uterus cancer. Three of these, you’ll note, are seen at higher rates in diabetics.
Lack of regular exercise is associated with higher cancer rates.
If I were a type 2 diabetic wanting to reduce my risk of cancer, I’d be sure to exercise regularly, keep my body mass index under 30 (if not lower), refrain from smoking, consider a Mediterranean-style diet, and ask my doctor to monitor for onset of cancer.
Reference: Giovannucci, E., Harlan, D., Archer, M., Bergenstal, R., Gapstur, S., Habel, L., Pollak, M., Regensteiner, J., & Yee, D. (2010). Diabetes and Cancer: A Consensus Report CA: A Cancer Journal for Clinicians DOI: 10.3322/caac.20078