Longevity escape velocity
Longevity escape velocity' is a term coined by David Gobel of M foundation to describe what will happen when medical technologies reach a point whereby they extend healthy lifespans by 1 year or more for every year of research and development in medical technologies and treatments.
Currently, it takes more than 1 year of advancement for an increase of 1 year in lifespans, if these 2 things shift in the opposite direction, and 1 year of advancement adds 1 year or more to lifespans, then longevity escape velocity will be achieved. The point at which indefinite lifespans may be reached is sometimes referred to as the Methuselarity.
Although the amount of time that a given breakthrough could grant us is unknown, the average educated guess on that amount of time is roughly 20 years. The defeat of other similar diseases and afflictions will typically give a person 20 or so years of additional life. So if breakthrough A. allows you to live to 100, and breakthrough B. gets here when you are 99, allowing you to live to 117 or so, and breakthrough C. gets here when you are 116, allowing you to live to 141, then you could continue on like this and obtain indefinite life extension in this way.