In the video she says that she underwent abdominal surgery and at the time they thought it wasn't cancerous, but subsequent tests showed that it was. And they she was recommended to have preventative chemo.
Sounds to me like they removed an abdominal tumour, it was probably successfully removed, and now she's getting chemo just in case there's any spreading or any they missed.
I don't know, I just don't think she's comfortable with fighting this battle in public. Considering how wild some conspiracy theories were getting, this info was probably just released to shut people up.
The news article/statement I read has it related to major abdominal surgery from back in January. So none of the good kinds. Not that any cancer is good.