Awareness and Utilization of the Revised Second International Staging System (R2-ISS) and 1q21 Gain/Amplification Testing: A Nationwide Web-Based Survey of Hematologists in Japan.

BACKGROUND

Although the multiple myeloma (MM) treatment landscape has significantly advanced, MM remains an incurable disease. Accurate risk stratification and its broad clinical implementation are essential for optimizing treatment strategies. International Staging System (ISS), its revised versions (R-ISS and R2-ISS), and cytogenetic testing for abnormalities such as chromosome 1q21 gain/amplification are recognized tools for risk assessment. However, the level of awareness, use, and barriers to implementation of these tools in clinical practice in Japan have not been elucidated.

OBJECTIVE

To evaluate the current utilization of ISS-related staging systems among Japanese hematologists and to identify barriers to the implementation of R2-ISS and 1q21 gain testing.

METHODS

The survey was conducted through a medical information platform with 280,000 registered physicians in Japan. A web-based questionnaire was distributed to hematologists between July 1-31, 2024. A total of 143 hematologists responded. The survey assessed awareness and utilization of staging systems and the implementation status of 1q21 gain testing.

RESULTS

Among the respondents, 61% routinely used ISS, 71% used R-ISS, whereas only 27% used R2-ISS. Major perceived barriers to R2-ISS adoption included limited insurance coverage (45%), lack of awareness of its clinical utility (37%), and the perception that 1q21 testing is not essential for risk stratification (24%). R-ISS was widely used regardless of the facility type or the number of patients treated with MM. For 1q21 gain/amplification testing, 53% of physicians always performed the test, with higher implementation among physicians annually treating ≥ 10 patients with MM.

CONCLUSION

Although ISS and R-ISS are widely utilized by Japanese hematologists, the adoption of R2-ISS and 1q21 testing remain limited. The findings suggest that for broader adoption of R2-ISS, the key barriers, such as limited insurance coverage for fluorescence in situ hybridization testing, insufficient awareness, and lack of integration into national clinical guidelines, should be addressed.