D-Limonene and cancer

[intv]

I picked up a Men's Health for the first (and last) time the other day, and happened to read about studies using d-limonene to ward off skin cancer. I'd never heard of this, is this old news? A google search yields several interesting links:

http://www.sunkist.com/snb/press/06_03_skin_cancer.asp

http://www.positivehealth.com/permit/Articles/Cancer/brud53.htm

http://www.applesforhealth.com/lemonpeel1.html

pubmed:
http://www.pubmedcentral.gov/articlerender.fcgi?tool=pmcentrez&rendertype=abstract&artid=161368

http://www.pubmedcentral.gov/articlerender.fcgi?tool=pmcentrez&rendertype=abstract&artid=45584