I think it depends as if indoor cats live in an enclosed flat and never venture out or are put in a cattery, there is very little risk. If they have access to a cat run, a much greater risk. I did an awful lot of research in 2005 while waiting for his surgery and spoke to 3 specialists in 3 countries, all of whom discourage rabies and leukaemia vaccines unless necessary (the flu ones are safer). It's the adjuvant (aluminium) which provokes the reaction which can be cancerous and if it is, it is a dreadful cancer. I am not trying to discourage people from vaccinating cats that should be vaccinated. I used to vaccinate mine every year for years. I just lived through a fibrosarcoma scare and it was terrifying. The pathology came back as 'benign, but of the type of tumour where you must continue to survey the site'. He was 13 then and had to undergo a major operation, just because of the over vaccination of pets under the Passport Scheme.
Annual vaccination is really OTT imho. Plus if you do vaccinate, don't let the vet do it between the shoulder blades. It is a really difficult site to remove a lump from. Better on the flank or (as in US and Oz) in the leg. Non vaccination unless absolutely necessary if your cat has had a vaccine related tumour as apparently it means they are predisposed.
Once the drug cos move to non adjuvanted vaccines as at least one company are doing in America, it will be much safer.
The rate of fibrosarcoma in the UK is very low, but in countries where annual rabies jabs are insisted upon (and leucogen) it is higher.
It's as well to be aware of the risk, that's all, and take a decision based on what's best for your cat.
