A more thorough explanation:

The increased-risk-of-harm doctrine, also known as the loss-of-chance doctrine, is a legal rule in some states that allows a patient to sue a doctor for medical malpractice even if the malpractice did not directly cause a particular injury. Instead, the doctrine applies when the malpractice decreases or eliminates the chance of surviving or recovering from a preexisting condition for which the doctor was consulted.

For example, suppose a patient has a 50% chance of surviving a particular type of cancer if it is caught early and treated properly. If a doctor fails to diagnose the cancer until it has progressed to a later stage, and the patient's chance of survival drops to 10%, the patient may be able to sue the doctor for the lost chance of survival, even if the malpractice did not directly cause the patient's death.

The increased-risk-of-harm doctrine is controversial because it can be difficult to prove that the malpractice caused the lost chance of survival or recovery. However, some states have adopted the doctrine as a way to provide compensation to patients who have suffered harm due to medical negligence.