Many of those cancers might be caused by pollution... For example, UV in sunlight is thought to be the main cause of skin cancer. UV is far higher today than 100 years ago because we destroyed most of the ozone layer. But we don't actually know how thick the ozone layer used to be or how much UV used to reach ground level because we never measured it before destroying it. So possibly skin cancer was very rare 100 years ago.

The same for cancer's from nitrous oxides from car exhausts. The same for particulate pollution. Same for microplastics. The same for all the kinds of pollution we don't yet know about or measure.

You're conflating trends within aggregated data and individual data points. Moving towards a healthier population would reduce cancer rates across the total population. It would not remove cancer entirely. Likewise any arbitrary person might be in complete health & get cancer and vice versa as you say. The two are not contradictory.

A similar example is with early detection. The data show that at population scale a lot of early detection efforts cause more harm than good. The problem is that any arbitrary person might have their life saved by said early detection. It's impossible to know who those arbitrary people will be.

Well, possibly polluters are to blame? Amongst developed countries, seems like USA stands out as having had a pretty cavalier attitude for decades about polluting land and water with carcinogens, allowing all sorts of cr*p in food etc. The reactive attitude "we'll permit this chemical until we run into any problems with it". vs the EU's "this chemical is suspect , so banned until we find clear evidence that it isn't dangerous". Of course EU not perfect either, plenty of scare stories in other places too. But the attitude in the USA baffles me, why isn't there more public pressure to reduce exposure to dangerous chemicals. is it just people are uniformed, or they think lets just dump it in a poor area or something.... ?