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 tha

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.