The variations in survival for blood cancer patients across Europe are most likely caused by variations in quality of care between regions, according to a new study published in The Lancet Oncology.

The largest population-based study of survival in European blood cancer patients to date, the EUROCARE study analyzed data from 30 cancer registries, which covered all patients diagnosed in 20 European countries.

More than 560,400 participants aged 15 years and older who were diagnosed with lymphoid and myeloid cancers between 1997 and 2008 were compared and followed up to the end of 2008.

The researchers found that there have been some large increases in survival from blood cancers during the study period of 1997-2008. Survival rates at the start and end of this period are as below:

  • Follicular lymphoma – 59% to 74%
  • Diffuse large B-cell lymphoma – 42% to 55%
  • Chronic myeloid leukemia – 32% to 54%
  • Acute promyelocytic leukemia – 50% to 62%.

The study notes that the greatest improvements in survival were in northern, central and eastern Europe. However, eastern Europe, who had the lowest survival rates in 1997, still have the lowest survival rates for most blood cancers.

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Compared with the UK, the excess risk of death was significantly higher in eastern Europe and significantly lower in northern Europe.

In southern Europe and the UK, survival gains have been lower than other regions. Below are the 5-year chronic myeloid leukemia survival rates across the European regions during 1997-2008:

  • Northern Europe – 29% to 60%
  • Central Europe – 34% to 65%
  • UK – 35% to 56%
  • Southern Europe – 37% to 55%.

The study also finds that risk of death within 5 years fell significantly for all forms of blood cancer during this period, except myelodysplastic syndromes.

However, compared with the UK, the excess risk of death was significantly higher in eastern Europe and significantly lower in northern Europe.

Suggesting reasons for geographical differences in survival, the authors say the availability and use of new treatments across different regions is key.

“We know that rituximab, imatinib, thalidomide, and bortezomib were first made available for general use in Europe in 1997, 2001, 1998, and 2003, respectively,” they write.

“The years following general release of these drugs coincided with large increases in survival for chronic myeloid leukemia, diffuse large B-cell lymphoma, and follicular lymphoma; with a smaller but still significant survival increase for multiple myeloma plasmacytoma.”

Alastair Munro from the University of Dundee Medical School in Scotland writes in a linked comment that survival may not just be about drug availability, however.

Better understanding of the conclusions from EUROCARE-5 requires additional information about changes over time (and space) affecting: survival according to the broad categories of disease (Hodgkin’s lymphoma, non-Hodgkin lymphoma, leukemias, myeloma, and other myeloid malignancies); the distribution of histological subtypes and their relation with the age distribution of the population; the distribution of stages at diagnosis; and the timing of active intervention for indolent tumors.

“When making comparisons, whether across time or space,” he says, “one should consider the effect of potential confounders. Is it all about the drugs? The answer is, not entirely.”