Multiple Myeloma Prognosis (ISS)
Understanding the International Staging System (ISS)
The International Staging System (ISS) is the standard prognostic tool for multiple myeloma. It uses two simple blood tests - serum β2-microglobulin and serum albumin - to classify patients into three stages with different survival outcomes. This staging system helps doctors determine prognosis and plan appropriate treatment strategies.
What is the International Staging System?
The International Staging System (ISS) was developed through analysis of over 10,750 patients from 17 institutions worldwide. It provides a simple, reliable way to stratify patients into three prognostic groups based on serum β2-microglobulin and albumin levels at diagnosis.
ISS Stages and Prognosis
Stage I
- β2-microglobulin < 3.5 mg/L AND
- Albumin ≥ 3.5 g/dL
- Median survival: 62 months
Stage II
- Neither Stage I nor Stage III
- Median survival: 44 months
Stage III
- β2-microglobulin ≥ 5.5 mg/L
- Median survival: 29 months
Clinical Significance
The ISS staging system:
- Was validated across North America, Europe and Asia
- Works equally well for patients under and over 65 years old
- Is effective for both standard chemotherapy and high-dose therapy patients
- Provides more equal distribution of patients across stages compared to the older Durie/Salmon system
- Uses simple, widely available laboratory tests (β2-microglobulin and albumin)
When to Use ISS Staging
ISS staging is typically used:
- At initial diagnosis
- Before starting treatment
- For research purposes
- To monitor disease progression
Factors Affecting Prognosis
β2-microglobulin levels can be affected by
- Tumor burden
- Kidney function
- Age
- Overall health status
Albumin levels can be affected by
- Nutritional status
- Liver function
- Inflammation
- Chronic illness
Clinical Applications
The ISS is particularly useful for:
- Initial staging
- Treatment planning
- Clinical trial eligibility
- Comparing outcomes across centers
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