I'm praying for your mother tonight and for you, too. I hope you get some good news soon. I totally understand why you would think the worst. It's kind of human nature, but try to remember that keeping a positive state of mind will be important for your mom regardless of what she's facing, It'll be easier for her to stay positive if the ones around her do.
I hope everything is going well. I've never had to deal with chest issues for anyone in my family, but my mom did have cancer. It was scary for all of us. Thankfully she was cured and has been healthy since then. Hoping good things for you and your mom!
I am so sorry to hear about this. I have dealt with a few cancer scares in my family. I know when you hear the word 'Cancer' it's such a scary, threatening word. But often times there is hope, these symptoms your Mom experienced may have been a miracle so there could be early diagnosis and treatment. My suggestion is stay informed by the doctors and just be there for your Mom as much as you can... don't research the internet, you will only drive yourself crazy w/ the 'what-if's'. Stay strong for your Mom as much as you can, she needs you now more than ever before... and she will probably surprise you w/ her strength during this very difficult time. You and your Mom are in my thoughts and prayers.