I totally agree with you I worried about being judged I did smoke (Did give up when I was diagnosed) there are millions of people who smoke and luckily do not get Cancer. 
Cancer is Cancer at the end of the day we did not ask for it hope you are supported by family and friend's. 
Try and ignore negative people. 
YOU GOT THIS 

WOW 15 years that’s amazing well done NO it should not be a question that is put to you  have only been 5 years smoke free 

To be honest it is none of anyone’s business if and when someone has stopped smoking. It is a matter to be discussed with your doctor only. I feel it is important not to judge anyone, you do not know their circumstances.

100% agree I hope lots of people read your post and gain courage from it to stand up to those who judge x

This is a really good observation Ysta. The fact you have lung cancer is bad enough without poorly informed people trying to blame you. There are many causes for lung cancer other than smoking. My sin was long term exposure to the sun because of my outdoor occupation now incurable metastatic skin cancer. Should people scorn me for not being more careful, while they themselves take an annual beach holiday. One in two people will get cancer and the last thing they deserve is somebody telling them that they only have themselves to blame. Anyway you have my sympathy for enduring these comments.

Ed