Does any one know of or have used themselves any topical preparations to effectively treat pre cancerous skin spots ie Keratosis?

My best and safest advise would be to visit a dermatologist/ oncologist if you haven't already done so, and get everything checked out. That said, I have used diclofenic gel on my areas of 'skin change' twice per day for the last 18 months after my last lot of surgery and this (coupled with judicious use of a total skin sun block and hat wearing) seems to be holding things nicely at bay. This was at the suggestion of my doctor in the UK, the diclofenic acts as an anti-inflammatory agent. Go and see your doctor, they've got access to the latest, safest treatments suitable for your needs.

Topical application of 5 Fluo-uracil cream is usually used but is not regularly used due to the efficacy of freezing with liquid nitrogen. Has to be applied for 4-6 weeks and cause quite a bit of irritation and inflammation both in the leasions as well as surrounding skin.

This is a good summary of management: http://www.patient.co.uk/doctor/Actinic-(Solar)-Keratosis.htm