Minimal residual disease

Minimal residual disease (MRD), also known as Molecular residual disease, is the name given to small numbers of cancer cells that remain in a person either during or after treatment when the patient is in remission (no symptoms or signs of disease). Sensitive molecular tests are either in development or available to test for MRD. These can measure minute levels of cancer cells in tissue samples, sometimes as low as one cancer cell in a million normal cells, either using DNA, RNA or proteins.

MRD detection is strongly associated with cancer recurrence. Often with a lead time of months relative to other forms of clinical evidence.

The tests are minimally invasive (involving a simple blood draw). Monitoring is performed every three to six months. MRD monitoring may be performed as part of research or clinical trials, and some have been accepted for routine clinical use. MRD is a form of liquid biopsy, which has other applications such as multi-cancer screening tests.

Molecular tests that uncover minimal residual disease are helpful for directing treatment and monitoring or preventing relapse.