Minimal Residual Disease Testing

Content Review: December 2022 Last Update:

Minimal residual disease (MRD, also called measurable residual disease) is the term for very small numbers of cancer cells that a patient retains after treatment. MRD is a major predictor of relapse in many hematologic malignancies (leukemias and lymphomas) and has important implications for prognosis and treatment decision-making. Recent increases in test sensitivity enable the detection of very small numbers of cancer cells, and thus detection of MRD, in hematologic malignancies. Laboratory techniques used in MRD assessment include polymerase chain reaction (PCR), deep sequencing (a type of next generation sequencing, or NGS), and flow cytometry.

Quick Answers for Clinicians

For which malignancies is minimal residual disease assessment recommended?

The National Comprehensive Cancer Network (NCCN) and European Society for Molecular Oncology (ESMO) recommend minimal residual disease (MRD) assessment for specific hematologic malignancies, including acute myeloid leukemia (AML), B-cell acute lymphoblastic leukemia (B-ALL), chronic lymphocytic leukemia (CLL), chronic myeloid leukemia (CML), and multiple myeloma. -  MRD may also be assessed in some circumstances (such as in the context of clinical trials) in other hematologic malignancies (eg, hairy cell leukemia, some myeloid/lymphoid neoplasms with eosinophilia, follicular lymphoma, and mantle cell lymphoma).    

What is the role of minimal residual disease testing in nonhematologic malignancies?

The role of minimal residual disease (MRD) assessment in patients with solid tumors (eg, melanoma and breast cancer) is currently being researched. There are currently no recommendations for the use of MRD testing in nonhematologic malignancies.

Which factors should be considered when choosing a test for minimal residual disease?

Assays specifically designed for minimal residual disease (MRD) testing are recommended. For flow cytometry tests, a sufficient number of colors should be used, and the validated limit of detection (LOD) should be reported. For example, in multiple myeloma, an LOD of 0.001% is required. An eight-color, two-tube flow cytometry test or a 10-color, one-tube test can meet this requirement and provide high consistency, reliability, and sensitivity. Although the use of flow cytometry and/or polymerase chain reaction (PCR) testing in MRD assessment is established for many hematologic malignancies, the role of next generation sequencing (NGS)-based tests continues to evolve. Regardless of the test selected, a high-quality specimen should be provided for testing (eg, a first or early pull of bone marrow), and the test should be thoroughly validated.

Indications for Testing

MRD testing may be used in hematologic malignancies to:

  • Assess treatment response and inform treatment decisions
  • Determine prognosis
  • Monitor remission and detect recurrence

Laboratory Testing

Testing Methods

A variety of methods are used to detect MRD. The most frequently used methods are deep sequencing (a type of NGS), flow cytometry, and PCR. The choice of which technique to use depends on the phenotype and molecular signature of the disease; for example, PCR may only work for a subset of cases with specific molecular findings. Use of multiple techniques or multiplexed tests that combine techniques may decrease the likelihood of false-negative results, but can be costly. 

Regardless of the technique used, high sensitivity (ie, low limit of detection [LOD] or limit of quantification [LOQ]) is required to ensure detection of very small numbers of leukemic cells. The requisite LOD/LOQ is generally 0.01% of nucleated cells or less, depending on the disease.

Other testing methods, such as fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC), have been used for MRD assessment in specific hematologic malignancies.  

MRD Assessment in Specific Hematologic Malignancies

For more information about MRD testing and other laboratory testing in specific hematologic malignancies, see the following ARUP Consult topics and Test Fact Sheets:

ARUP Laboratory Tests

For more information about ARUP MRD test offerings, see Minimal Residual Disease on


Specimens: bone marrow, whole blood

LOD/LOQ: 0.0072%

Specimen: bone marrow

LOQ: 0.005%


Specimens: bone marrow (preferred for maximum sensitivity), whole blood

LOQ: 0.01%

Specimens: bone marrow, whole blood

LOQ: 0.001%

Specimens: bone marrow (preferred for maximum sensitivity), whole blood

LOQ: 0.001%

Specimens: bone marrow (preferred for maximum sensitivity), whole blood

LOQ: 0.001%

Specimens: bone marrow, whole blood

LOD/LOQ: 0.0032% international scale (IS)


Specimens: bone marrow, whole blood

LOD: 0.0039%

LOQ: 0.01%


Specimens: bone marrow, whole blood

LOD/LOQ: 0.0032% IS

Specimens: bone marrow, whole blood

Multiple Myeloma


Medical Experts



Kristin Hunt Karner, MD
Associate Professor of Pathology (Clinical), University of Utah
Medical Director, Hematopathology and Molecular Oncology, ARUP Laboratories