We have discussed this several times over the years and I'll let the Brian's and the Jerry's add their technical explanation but it does appear possible that constant irritation can contribute to cellular damage which can lead to cancer.

David

Age 58 at Dx, HPV16+ SCC, Stage IV BOT+2 nodes, non smoker, casual drinker, exercise nut, Cisplatin x 3 & concurrent IMRT x 35,(70 Gy), no surgery, no Peg, Tx at Moffitt over Aug 06. Jun 07, back to riding my bike 100 miles a wk. Now doing 12 Spin classes and 60 outdoor miles per wk. Nov 13 completed Hilly Century ride for Cancer, 104 miles, 1st Place in my age group. Apr 2014 & 15, Spun for 9 straight hrs to raise $$ for YMCA's Livestrong Program. Certified Spin Instructor Jun 2014.