Hi Monica
Whilst I understand you want to avoid trauma for your cat, if there really is a risk that this is a tumour you should take your vet's advice and let them amputate the tail. I can promise you that a cat manages fine without a tail. If you dont trust your vet's judgement or the diagnosis then I can only suggest you seek a second opinion from another vet before any decision.
Cathy Wickenden BVet Med MRCVS
Barton Lodge Veterinary Centre
1 Midland Road, Hemel Hempstead, Hertfordshire, HP2 5BH
Tel: 01442 216048 24 hours
[
www.bartonlodgevets.co.uk]