I would certainly go back to the GP and tell him that he missed a cancer diagnosis and you want to be sure that doesn't happen again. You don't have to go through the expense and probably long term frustration of filing a lawsuit to do that. I had my plainly visible tongue cancer overlooked at two regular dental appointments (they were teeth cleaning but the dentist looked in my mouth at the end) and only caught at the third one. Right after that dental appointment, before I got into see the oral surgeon who did a biopsy and diagnosed it as cancer, I had a physical with my GP and he also looked at the tumor and said it looked to him like a spot on my tongue that was irritated by a tooth (which was what I thought it was).

Later when I saw him after my diagnosis, he did apologize for that and said he had actually never seen tongue cancer before. This was not a newly minted GP but a 40-somehting-ish GP who is very conscientious about learning whatever he can about diseases and medical conditions (makes regular rounds at our local hospital as I found out when I ended up there after treatment--and it is in part to see patients of his but in part just to learn). I am less forgiving of my dentist who never apologized for not catching it earlier - and had it been caught earlier I would not have needed radiation.

Nelie