New research from Karolinska Institutet shows that the survival for patients with chronic myeloproliferative diseases has improved in recent decades. This is despite the fact that no targeted drugs have yet been registered for this group of diseases. More than 9,000 patients have been included in a unique population-based study which has been published in the Journal of Clinical Oncology.
In Sweden, around 450 people are diagnosed each year with chronic myeloproliferative diseases, a group of three disease subtypes that are characterized by the production of excess cells in the bone marrow. Polycythemia vera results in the overproduction of red blood cells, essential thrombocytosis leads to the overproduction of platelets, and primary myelofibrosis involves the overproduction of connective tissue in the bone marrow, leading to decreasing blood counts.
These diseases also involve an increased risk of complications such as blood clots (thrombosis) and bleeding (hemorrhage). The treatment, provided in the form of phlebotomy, radioactive phosphorus, or cytotoxic agents, aims primarily to alleviate symptoms and reduce the risk of complications.
The study included all cases of chronic myeloproliferative diseases reported to the Swedish Cancer Registry between 1973 and 2008, a total of 9,384 patients. The results show that even patients with the mildest form of myeloproliferative disease - essential thrombocytosis - have a lower life expenctancycompared with the normal population, which has not previously been thought to be the case.
In contrast to certain previously published studies, patients suffering from polycythemia vera were also shown to have a shorter life expectancy. As expected, primary myelofibrosis patients had a shorter life expectancy compared with the normal population.
"At the same time, we note that the survival rates for patients with polycythemia vera and essential thrombocytosis have improved during the study period. This is very encouragingm", says Malin Hultcrantz, who led the study.
For essential thrombocytosis patients, the life expectancy was almost at the same level as the normal population during the most recent period, 2001 to 2008.
"There is a great deal of interest within medical research in devising and developing new treatments for these diseases", says Malin Hultcrantz. "We hope that the prognosis in myeloproliferative diseases will continue to improve, ideally at a faster rate."
Patterns of survival among 9,384 patients with myeloproliferative neoplasms diagnosed in Sweden 1973-2008; a population-based study. Malin Hultcrantz, Sigurdur Yngvi Kristinsson, Therese M-L Andersson, Ola Landgren, Sandra Eloranta, Åsa Rangert Derolf, Paul W. Dickman & Magnus Björkholm. Journal of Clinicial Oncology, July 16, 2012; DOI:10.1200/JCO.2012.42.1925.