mother in law....

So in a earlier post I mentioned I was concerned because my fiancé has two lumps on one of his balls. The last update was he promised he would go to the doctors soon. Well after this weekend she convinced him it was a bakers cyst because she has one in her lower region. This is said after my fiancé asked about her having ovarian cancer years ago. Now I'm stuck trying to convince him to go to the doctor all over again and explaining to him that cancer can be genetic and come in many forms. Wtf do I do. Any time I make progress in any aspect of his life he goes to her because he knows she'll say otherwise.