Cancer; squamous cell carcinoma of the floor of the mouth, second occurcence and the danger`s involved, what do you suggest?

Some ideas. If you are still smoking or using smokeless tobacco, stop. A recurrent cancer must be treated on an individual basis depending on how far it has gotten and what the pathologist found. I see you're only 35 years old and this makes your case atypical. Try to get to a cancer center that handles a lot of these cases.