Oh Conniecat , I'm so sorry to hear such bad news :(
My Chat Moche had a tumor too - under the skin - and he had surgery for that . I've heard that shark liver oil -  also called "squalene"   can help fighting against tumors( but do not confound with cartilage which is useless in our case ) .I gave it to my cat after the surgery and he is fine now - 1 1/2 year after the sugery .I don't know the efficiency due to the squalene but it worth trying , it's not very expensive -I've paid around 0.5 euro/cap- and quite easy to find   .I gave him 1 cap 500mg/ day - you pierce the cap and put the oil on his fur ,if he has the strength to lick it  .
Hope it's not too late for him .
Hugz
Alizea

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