How Is the ELTS Risk Score Calculated for CML at Diagnosis?

In Plain Language: The ELTS score is a baseline risk calculation for adults newly diagnosed with chronic-phase CML. It uses your age, spleen size, leukemia cell count, and platelet count from before you start treatment to estimate long-term prognosis. It is not a prediction of your personal life expectancy, and it does not replace the ongoing blood tests used to check if your medication is working.

When you are diagnosed with Chronic Myeloid Leukemia (CML), your doctor will calculate a risk score to estimate your long-term prognosis and guide treatment decisions. The modern standard for this is the ELTS (EUTOS Long-Term Survival) score ^[1].

It is important to understand that the ELTS score provides a population-level estimate of the risk of CML-related mortality—not your individual life expectancy ^[2]. The score was developed specifically for adults newly diagnosed with the chronic phase of CML ^[2]. If your CML is in an advanced stage (accelerated or blast phase), or if you have already started taking targeted therapies, the ELTS calculation does not apply in the same way ^[2].

The Four Variables Used

Your doctor calculates your ELTS score using four specific variables, all measured before you start any leukemia-directed treatment ^[1]:

The Math Behind the Score

Most clinics use an online calculator to determine your score, but the exact mathematical equation used is ^[1]:

$\text{ELTS} = 0.0025 \times (\frac{\text{Age}}{10})^3 + 0.0615 \times \text{Spleen Size} + 0.1052 \times \text{Blasts} + 0.4104 \times (\frac{\text{Platelet Count}}{1000})^{-0.5}$

The Risk Categories

The final number places you into one of three baseline prognostic groups ^[1]:

• Low Risk: A score of $1.5680$ or lower. In large validation studies, about 60% of patients fall into this group ^[2][3].
• Intermediate Risk: A score greater than $1.5680$ and up to and including $2.2185$.
• High Risk: A score greater than $2.2185$.

Because ELTS is much better at identifying long-term risk than older scoring systems (like the Sokal score), many patients who would have once been considered “high risk” are accurately reclassified as “low risk” under ELTS ^[3]. Keep in mind that a high-risk score does not mean treatment will fail, and a low-risk score is not a guarantee of success—they are simply starting points ^[3].

How the Score Influences Treatment

The European LeukemiaNet (ELN) recommends assessing your ELTS risk at diagnosis to help guide your initial therapy options ^[1]. Your score is just one piece of the puzzle. Choosing a daily targeted therapy (a tyrosine kinase inhibitor, or TKI) requires a shared decision between you and your oncologist.

While patients in the low-risk category often achieve excellent results with first-generation TKIs like imatinib ^[2], intermediate or high ELTS scores sometimes lead doctors to consider a second-generation TKI (such as dasatinib, nilotinib, or bosutinib) ^[4][5]. These second-generation medications can sometimes produce faster or deeper responses ^[4][5]. However, there is no rigid rule assigning a specific drug to a risk group. Your doctor will also heavily weigh your cardiovascular health, lung and liver function, other medications, side effects, pregnancy plans, and personal preferences ^[1].

A Note on Treatment-Free Remission: Some patients hope to eventually stop taking their TKI—a goal known as treatment-free remission (TFR). While second-generation TKIs might get some patients to a deep molecular response faster, imatinib can also lead to TFR for eligible patients ^[5][4]. Regardless of the medication, stopping a TKI is only considered after years of sustained, deep molecular response, requires strict medical supervision, and should never be attempted on your own ^[5][4].

Ongoing Monitoring (BCR::ABL1)

Your ELTS score is a one-time calculation made at diagnosis. Once treatment starts, your doctor will track your actual progress using a specialized blood test that measures BCR::ABL1 ^[1]. This test looks for the genetic signal of your leukemia. Over time, you want this number to go down. Rather than comparing your BCR::ABL1 test to your initial ELTS score, your doctor uses specific BCR::ABL1 milestones to assess whether your treatment is working adequately or if a medication change is needed ^[1].