I cannot cite a reference but I read a long time ago that cancer was thought to be a shameful disease and afflicted “bad people”, if someone in your family had it, you kept it quiet. Like syphilis or AIDS.
I really thought that people were much more enlightened nowadays. We’d be hard pressed to find anyone on this forum whose lives have not been touched by this disease in some way. A relative or other loved one, it touches everybody, good and bad, indiscriminately.
If you were particularly enlightened, you’d know about the causal link, in some cases, between mental status and physical illnesses. It’s called “psychosomatic”. It’s not completely understood, of course, but cancer is one of the big lump of occurrences in this class.
Try not to rely so much on what you thought you heard a long time ago and fitted into your belief system.