Implementation of Standardized International Karyotype Scoring Practices Is Needed to Provide Uniform and Systematic Evaluation for Patients with Myelodysplastic Syndrome Using IPSS Criteria: An International Working Group on MDS Cytogenetics Study

BACKGROUND: The International Prognosis Scoring System (IPSS) for evaluating the clinical outcome for patients with myelodysplastic syndromes is widely used to estimate overall survival and time of progression to acute myeloid leukemia. Karyotype status and complexity are key components of the IPSS; however, emerging data suggest the use of cytogenetics at disease presentation is not applied uniformly among MDS patients.

AIM/METHODS: To investigate the degree of consistency of scoring karyotypes for IPSS among cytogeneticists and clinicians, the International Working Group on MDS Cytogenetics (IWGMC) conducted a survey of 32 karyotype challenges carried out in two phases:

• an initial survey without any specified karyotype counting guidelines and

• a second survey conducted after the development of IWGMC consensus guidelines for scoring karyotype complexity.

The consensus guidelines for counting aberrations were:

1. count 1 aberration for each numerical change (including –Y), balanced translocation and simple structural change;

2. count 1 aberration for each complex structural change;

3. count 0 for a constitutional aberration, but if in doubt, count 1 aberration;

4. when multiple clones are present, add all independent aberrations, but count a single (specific) change only once;

5. count 1 aberration for tetraploidy; and

6. until it is revised, all chromosome 7 abnormalities are considered “poor”.

The number of cytogenetic aberrations and the corresponding IPSS score (Good, Intermediate or Poor) were also to be given for each of the karyotypes. Twenty cytogeneticists and two clinicians participated in the initial survey. The second survey with attached IWGMC guidelines was completed by 23 cytogeneticists and 16 hematologists working at MDS Foundation Centers of Excellence worldwide.

RESULTS: Despite the excellent concordance in the evaluation of simple karyotypic aberrations, major differences in scoring complex abnormalities were observed among the cytogeneticists who participated in the initial survey. After implementation of the IWGMC guidelines, scoring among the cytogeneticists in the second survey became homogeneous (<10% discrepant results). However, scoring among the hematologists remained much less consistent, with difficulties surrounding ploidy and complex rearrangements/karyotypes. These data and the results of a recent international physician’s practice survey conducted by the MDS Foundation, Inc., indicating 86% of 98 respondents state cytogenetic results had impact on their management of MDS patients and cytogenetic scoring is most often assigned by hematologists (67%), support the need for standardized karyotype scoring practices. These data also highlight that a number of unresolved issues with karyotype status and complexity scoring remain, including the status of –Y, classification of 7p abnormalities, and ploidy status and count.

CONCLUSIONS: Our survey results indicate that cytogeneticists are capable of scoring karyotype complexity consistently with the consensus guidelines, whereas the hematologists remain slightly more puzzled by the nomenclature. Furthermore, despite these consensus guidelines, there remains a number of unresolved issues with karyotype status and complexity scoring. Therefore, our results argue for the immediate need of an international standardized complexity scoring system as well as a corresponding IPSS cytogenetic scoring system for clinical practice. We also argue that cytogeneticists must become more proactive in the management of MDS patients by implementing an immediate practice change that includes the IPSS karyotype score on the cytogenetics reports of all newly diagnosed MDS patients. Assisting the hematologists in this manner would ensure that cytogenetic data are applied in a uniform and systematic (comparable) manner, especially when new therapeutic approaches for MDS patients are being evaluated.