The finding means that x-rays (including fluoroscopy and CT scans) have become a necessary co-actor — – but not the only necessary CO-actor — – in causing most of the death-rate from Cancer and from Ischemic Heart Disease (also called Coronary Heart Disease, and Coronary Artery Disease).
In multi-cause diseases such as Cancer and Ischemic Heart Disease, more than one necessary CO-actor per fatal case is very likely. Absence of any necessary CO-actor, by definition, prevents such cases. The concept of x-ray-induced cases means cases which would be absent in the absence of exposure to x-rays.
X-rays and other classes of ionizing radiation have been, for decades, a proven cause of virtually all types of mutations — – especially structural chromosomal mutations (such as deletions, translocations, and rings), for which the doubling dose by x-rays is extremely low. Additionally, x-rays are an established cause of genomic instability, often a characteristic of the most aggressive Cancers.