regression
Meaning of regression: Three fields borrowed the same Latin idea of going backward, and the meanings that resulted have almost nothing to do with each other.
Definition of regression
Regression is a decrease in the size or extent of a disease process, most often a tumor that shrinks after treatment or, less commonly, on its own. The word carries two further meanings that share nothing with this one: the loss of skills a child had already acquired, and a statistical method describing how one measurement changes with another.
What does regression mean in cancer care?
It means the disease has become smaller or less extensive, judged by examination, imaging or a marker in the blood. Because shrinkage needs to be compared consistently between patients and between studies, it is graded against defined categories rather than described loosely.
| Category | What it means |
|---|---|
| Complete response | No disease detectable by the methods being used |
| Partial response | Shrinkage beyond a defined threshold, with disease still present |
| Stable disease | Neither enough shrinkage nor enough growth to count as either |
| Progression | Growth beyond a defined threshold, or a new site appearing |
Regression is not the same as cure. Disease can retreat below the level any scan can detect and still be present, which is why the outcome a study reports matters as much as the size change it observed. Spontaneous regression, where a cancer shrinks without treatment, is genuine but rare, and is best documented in melanoma, kidney cancer and neuroblastoma.
What does regression mean in child development?
Here it describes losing ground that was already gained: a child who spoke in words and stops, who walked and no longer does, or who withdraws from social contact previously enjoyed. This is different from being slow to reach a milestone in the first place, and the difference is what makes it significant. Loss of established skills points toward a neurological, metabolic or genetic condition, and mild, temporary regression in toileting or sleep also follows upheaval such as illness or the arrival of a sibling.
What does regression mean in statistics?
It is a method for fitting a line or curve that describes how an outcome changes as one or more other measurements change, and for estimating how much of that relationship survives once other factors are accounted for. The name comes from an early observation that the children of unusually tall parents tended to be closer to average height, a pull toward the middle known as regression to the mean. That effect is a standing trap in medicine: any group selected because its measurements were extreme will tend to look better on remeasurement, whether or not anything was done for it.
Used in a sentence
Follow up imaging showed regression of the tumor after the course of treatment.
Good to know
Regression names three largely unrelated ideas, shrinkage of disease in oncology, loss of previously acquired skills in child development, and a statistical method in research, so the intended meaning depends entirely on context.
Word origin
Where “regression” comes from
Formed from Latin regredi, meaning to go back, from re-, meaning back, and gradi, meaning to step or walk.