I would talk about the importance of maintaining strength through resistance training and would focus on easy-to-handle equipment like bands that are not intimidating and can be adjusted easily to the needs of the user. I often bring props to talks like that that can be passed around so that people can get a ‘feel’ for it.
I would mention something about reducing risk of reaccurrence. Here is a good guide.
I did read a report some years back that even one hour a week of aerobic exercise at a moderate intensity lowered risk of cancer for women, and reacurrance. Unfortunately, I don’t know how to access the report and I would not quote something without the statistical source to back it up. However googling may produce it.
Worthy mission you have taken on,
All the best.