Thank you all.

I've been checked two weeks ago but the problem is that even for a doctor it is difficult to judge at a glance if this white zone is bad or not. Perhaps it would be necessary to do a biopsy bad certainly it is too early to do it. My doctor said that in that zone was the main radiotherapy target and that's the reason for this white patch. It would be a very bad luck that being the main target the cancer wouldn't have been killed completely there, but it is possible.

I look this white several times per day and it seems not to grow. I don't know how much time I would expect to do a biopsy.