I wonder what our increasingly clean world has to do with this. I think there has been an uptick in autoimmune disorders that has been sometimes attributed to a lack of stuff like dirt and bacteria in our normal environments. I know that gut autoimmune issues are a huge risk factor for colon cancer.
Although, my personal main suspect would be obesity. Cancer and obesity go together really well.
all of these intuitions are right, it's the stress, the environmental pollutants, the empty calories, the nutritional deficiencies, and, as you said, excessive hygiene and underexposure to pathogens particularly during childhood (even cesarian birth contributes to gut dysbiosis), overreliance on pharmaceutical drugs that do more harm than good, all in all a gross misunderstanding of what constitutes health and how the human body works
Although, my personal main suspect would be obesity. Cancer and obesity go together really well.