What do remission, recurrence, and progression mean?
In oncology, remission, recurrence (recidivism/relapse), and progression are fundamental concepts used to describe the status of a malignant disease and the response to treatment:
1. Remission: Refers to the reduction or complete disappearance of the signs and symptoms of cancer. It can be partial remission (when the size of the tumour or the number of cancer cells in the body decreases significantly, but not completely) or complete remission (CR), when no active tumour can be detected by standard imaging, laboratory, and clinical examinations. Remission does not necessarily mean a permanent cure, as microscopic cells (minimal residual disease) may remain.
2. Recurrence (recidivism or relapse): The return of the cancerous disease after a period during which the patient was in remission or the tumour was undetectable. Recurrence can occur locally (at the site of the original tumour), regionally (in nearby lymph nodes), or distantly (in the form of metastasis to other organs).
3. Progression (disease progression): Refers to the growth, spread, or increase in tumour burden. This can occur during treatment (due to therapeutic resistance) or during a period of observation, and it involves an increase in the size of existing lesions or the appearance of new metastases.
The precise determination of remission, recurrence, and progression is carried out according to standardised oncological criteria (such as the RECIST system used for solid tumours) using imaging examinations (CT, MRI, PET-CT) and tumour markers.