How should I go about this?

This may sound strange to many of you, but I have this strange ability to smell advanced cancer in some people. I worked in an acute care hospital for 6 years and in that time noticed that some patients had a VERY DISTINCTIVE foul smell about them. Turns out they all had cancer of some type. I know I’m not crazy because there were a few other therapists who had experienced this as well. So not too long ago I noticed this distinctive smell again while visiting a friend of mine who is nearly 57 y/o. Now, I am not a doctor, however this is a smell you would never forget. I didn’t say anything to my friend directly, but did ask him when the last time he had any blood work done, which he sort of fluffed me on. Do I come right out and say something? I don’t really want to freak him out but I strongly feel this needs to be addressed asap. How should I go about this? I need some advice. Thanks.