progression
Meaning of progression: The point at which a disease is judged to be gaining ground, decided by measurement rather than by how a person feels.
Definition of progression
Progression is the worsening or spread of a disease over time. In cancer care it carries a specific meaning: a tumor has grown beyond an agreed threshold on imaging, new deposits have appeared, or a marker in the blood has risen consistently. It is decided by comparison with an earlier measurement rather than by symptoms alone.
How is it decided?
Standard response criteria set the rules in advance. A small number of measurable lesions are chosen as targets and their sizes are added up. At each assessment the total is compared with the smallest total recorded so far. Growth beyond a set proportion counts as progressive disease, and so does any unequivocal new lesion, however small the change in the targets. Applying identical rules at every center is what allows the results of different trials to be compared at all, and it is why a report may state that disease progression has occurred even when a patient feels no different.
What are the related terms?
| Term | Meaning |
|---|---|
| Time to progression | Time from a starting point until the disease progresses, with deaths counted separately |
| Progression-free survival | Time until progression or death from any cause, whichever comes first |
| Recurrence | Return of disease after a period with none detectable |
| Refractory | Never responded to the treatment at all |
| Relapse | Return after a response had been achieved |
What can look like progression but is not?
Several things. Immunotherapy can draw immune cells into a tumor so that it swells before it shrinks, an appearance called pseudoprogression. Radiation leaves inflammation and later scarring that can resemble growth. A new spot may be an infection or a benign lesion rather than a deposit of tumor. Measurements taken with different scanners, or by different readers, vary by enough to matter at the margins. Repeat imaging after a short interval, a change of technique or a biopsy is used to settle the question.
Is the word used outside cancer?
Widely. Progressive kidney disease, progressive multiple sclerosis and progression of liver scarring all describe steady worsening, and each field defines it against its own measurements rather than a shared standard. Kidney disease is tracked by filtration rate, multiple sclerosis by disability scales, and liver disease by the stage of scarring, so the same word carries a different technical meaning in each.
Also known as
Used in a sentence
Imaging at three months showed progression with two new liver lesions.
Good to know
Progression is defined against a previous measurement and a stated threshold, so a small increase in the size of a tumor on a scan does not by itself meet the definition.
Word origin
Where “progression” comes from
From the Latin progredi, meaning to go forward, built from pro, meaning forward, and gradi, meaning to step.