No. Many, many people have small, non-malignant cancers growing within us right now. Some people carrying such growths will develop life-threatening cancers, wh

No. Many, many people have small, non-malignant cancers growing within us right now. Some people carrying such growths will develop life-threatening cancers, whilst the rest (probably the vast majority) of the population will die of something else at a ripe old age before the growths in question ever become malignant. Once you start screening everyone, suddenly you have this huge population of growths that you have to biopsy in order to determine whether or not they're malignant or not. Your false-positive rate means that you start giving extremely harmful treatments (chemotherapy is itself mutagenic & can cause cancer!) to individuals who if they'd never have been scanned would have remained blissfully unaware of the harmless growth within them & would have had productive, happy lives. Routine scans are not cost free: They put a huge diagnostic burden on the system & they inevitably mean that you deliver invasive, potentially harmful treatments to people that don't need them.