Myelofibrosis is a neoplastic disorder of the myeloid hematopoietic stem cells. It can either be primary or secondary subsequent to other disorders, such as polycythemia vera and essential thrombocytosis. It is relatively a rare disorder of marrow, which is accompanied by bone marrow fibrosis. It is grouped under myeloproliferative neoplasms, which also include polycythemia vera, essential thrombocythemia and unclassified myeloproliferative neoplasms. The disease is quite rare and mostly seen in elderly people over 50-60 years of age and has male predilection. The etiology of the disease is still unclear, but prior radiation and exposure to solvents such as benzene and toluene have been implicated as risk factors. It is associated with anemia, leucopenia/leucocytosis, thrombocytopenia/thrombocythemia, splenomegaly, hepatomegaly and symptom manifestation and complications associated with these abnormalities.
What Is The Life Expectancy Of Someone With Myelofibrosis?
Patients with myelofibrosis have poorer survival when compared to general population. They also have reduced life expectancy in comparison to other myeloproliferative neoplasms (polycythemia vera, essential thrombocythemia). These findings were supported by a study in a cohort of 9000 patients. When compared to polycythemia vera and essential thrombocythemia, myelofibrosis patients survival rate did not improve over time. They were also at a greater risk of transformation to myelodysplastic syndrome and acute myeloid leukemia. The wide mortality in patients with myelofibrosis is modified by increased risk of bleeding, thromboembolic occurrences, infections, cardiac failure, hepatic failure, renal failure and postsplenectomy mortality. (1)
Age is another predictor of life expectancy in patients with myelofibrosis. Since the disease is found in elderly population, increased age (>65 years) is associated with poorer prognosis. This could be attributed to more aggressive form of disease in older individuals and relatively higher complications associated with the elderly. Male gender is also another prognostic factor associated with reduced survival. Given this, females have a better survival rate than males, the reason behind this still being unclear. Bone marrow vascularity is increased in about 70% patients with myelofibrosis and it is also an indicator of poor prognosis. Other indicators of poor prognosis include anemia, leucopenia, leucocytosis, thrombocytopenia, circulating blasts, karyotype abnormalities, elevated granulocyte precursors and symptoms of increased metabolism.
The median survival of patients with myelofibrosis is 3.5-5.5 years and the 5 year survival is reduced to about half of expected for that appropriate age group and sex. Approximately <20% patients survive for 10 years. A simple scoring system uses two risk factors, which include hemoglobin (<10 g/dl) and leukocyte count (<4000/ul or >30,000/ul). Patients with no risk factors are known to be low risk patients; patients with one of the risk factors are those who are intermediate risk patients; and patients who have both the risk factors are high risk patients. In addition, patients with abnormal karyotype have poorer prognosis than those who have normal karyotype. Low risk patients have a median survival of 93 months; intermediate risk patients have a median survival of 26 months and high risk patients have a median survival of 13 months. Patients with leucocytosis (>30,000/ul) and abnormal karyotype are associated with higher risk of transformation to acute myelogenous leukemia.
Although, the only cure for myelofibrosis is allogeneic stem cell transplantation, relatively only few individuals are candidates for it. It is also associated with high mortality rates, which further ads to decreased life expectancy of these patients even with treatment. There is only one FDA approved drug for myelofibrosis known as ruxolitinib (Jakafi) and although, it has shown promising results in managing the disease and improving life expectancy, there are further studies yet to be conducted. Other drugs used for the treatment of myelofibrosis are thalidomide, lenalidomide and interferon, out of which interferon has shown to improve fibrosis in bone marrow and no other existing treatment has modified the disease course. There is no disease specific therapy that has yet an effect on improving the survival of the patients. Therefore, there is need for optimization of myelofibrosis therapy and advent of new disease modifying therapies that are associated with improved survival of myelofibrosis patients. (2)