Prognosis

Myelodysplastic syndrome (MDS) secondary to antecedent haematological malignancy or following exposure to chemotherapy alone or with radiotherapy has a worse prognosis than de novo MDS.[3][93]

Patients aged under 60 years have a better survival rate than older patients. For older patients, overall median survival by risk group ranges from less than 6 months for high-risk patients to 5.7 years for low-risk patients.[64]

Cytogenetic abnormalities and somatic mutations

Chromosome 5q31 deletion (del(5q)), monosomy 7, 11q23, and TP53 mutations all have a poor prognosis.[94] TP53 mutations are associated with high-risk disease, with rapid transformation to acute myeloid leukaemia and chemotherapy resistance. Other somatic mutations associated with poor prognosis include ASXL1, ETV6, EZH2, and RUNX1.[95]

​SF3B1 mutations are associated with a more favourable prognosis.[62]

Prognostic criteria

Specific prognostic criteria were defined by the International Prognostic Scoring System (IPSS) working group in 1997 after a multivariate analysis of 816 patients with de novo MDS who were treated primarily with supportive care.[64] The IPSS used number of cytopenias, percentage marrow blasts, and cytogenetic abnormalities to categorise patients by risk for AML progression and death.

Revised International Prognostic Scoring System (IPSS-R)[63]

The IPSS-R refined the IPSS, using a larger patient database (n=7012) for analysis.[63] The IPSS-R scoring system includes five variables:

  • Bone marrow blast percentage:

    • ≤2 (0 points)

    • >2 to <5 (1 point)

    • 5-10 (2 points)

    • >10 (3 points).

  • Karyotype:

    • Very good (0 points): deletion Y or del(11q)

    • Good (1 point): normal karyotype, del (5q), del(12p), del (20q), a double abnormality, including del(5q)

    • Intermediate (2 points): deletion 7q, +8, +19, i(17q), and any other single or double independent clones

    • Poor (3 points): deletion 7, inv(3)/t(3q)/del(3q), double abnormalities including -7/del(7q), or three abnormalities

    • Very poor (4 points): complex karyotype (≥3 abnormalities).

  • Haemoglobin level:

    • ≥10 g/dL (0 points)

    • 8 to <10 g/dL (1 point)

    • <8 g/dL (1.5 points).

  • Platelet count:

    • ≥100,000/microlitre (0 points)

    • 50,000 to 100,000/microlitre (0.5 points)

    • <50,000/microlitre (1 point).

  • Absolute neutrophil count:

    • ≥800/microlitre (0 points)

    • <800/microlitre (0.5 points).

The IPSS-R score is calculated by adding each of these five values, and is divided into five groups based on the risk of AML development and overall survival. The IPSS-R was first validated in a set of 7012 patients with primary MDS. The five risk groups are:

  • Very low risk: ≤1.5

  • Low risk: >1.5 to 3.0

  • Intermediate risk: >3.0 to 4.5

  • High risk: >4.5 to 6.0

  • Very high risk: >6.

Median survival (without treatment) for the IPSS-R risk groups are:

  • Very low risk: 8.8 years

  • Low risk: 5.3 years

  • Intermediate risk: 3 years

  • High risk: 1.6 years

  • Very high risk: 0.8 years.

Time to 25% AML evolution for the IPSS-R risk groups are:

  • Very low risk: not reached

  • Low risk: 10.8 years

  • Intermediate risk: 3.2 years

  • High risk: 1.4 years

  • Very high risk: 0.7 years.

Molecular International Prognostic Scoring System (IPSS-M)[62]

The IPSS-M is a refined version of the IPSS and IPSS-R that combines somatic mutations (of 31 genes) with haematological and cytogenetic parameters to risk stratify patients with MDS. The IPSS-M classifies MDS patients into the following six risk groups based on a risk score derived from clinical (bone marrow blast percentage, platelet count, haemoglobin level), cytogenetic, and genetic prognostic factors (calculated using a web-based tool:  MDS Foundation: IPSS-M risk calculator Opens in new window):

  • Very low risk (risk score: ≤-1.5)

  • Low risk (risk score: >-1.5 to -0.5)

  • Moderate low risk (risk score: >-0.5 to 0)

  • Moderate high risk (risk score: >0 to 0.5)

  • High risk (risk score: >0.5 to 1.5)

  • Very high risk (risk score: >1.5).

Median overall survival for the IPSS-M risk groups are:

  • Very low risk: 10.6 years

  • Low risk: 6.0 years

  • Moderate low risk: 4.6 years

  • Moderate high risk: 2.8 years

  • High risk: 1.7 years

  • Very high risk: 1.0 years.

Risk of transformation to AML by 1, 2, and 4 years for the IPSS-M risk groups are:

  • Very low risk: 0%, 1.2%, and 2.8%, respectively

  • Low risk: 1.7%, 3.4%, and 5.1%, respectively

  • Moderate low risk: 4.9%, 8.8%, and 11.4%, respectively

  • Moderate high risk: 9.5%, 14%, and 18.9%, respectively

  • High risk: 14.3%, 21.2%, and 29.2%, respectively

  • Very high risk: 28.2%, 38.6%, and 42.8%, respectively.

Risk of death without AML by 1, 2, and 4 years for the IPSS-M risk groups are:

  • Very low risk: 2.2%, 7%, and 15.9%, respectively

  • Low risk: 8.5%, 16.2%, and 29.5%, respectively

  • Moderate low risk: 12%, 19.8%, and 33.6%, respectively

  • Moderate high risk: 18%, 31.1%, and 51.1%, respectively

  • High risk: 19.3%, 39.8%, and 54.2%, respectively

  • Very high risk: 30.6%, 45.6%, and 51.3%, respectively.

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