Significant current epidemiological trend: Haematological malignancies as subsequent primary tumours in cancer patients

•Risk of development of a haematological malignancy is 1.5 times higher in cancer patients than in the general population.•Sharp increase for subsequent haematological malignancies was revealed after 1992.•Survival of subsequent haematological malignancies is poorer than survival of a first haematological malignancy. Numbers of patients who develop subsequent primary tumours have markedly increased recently. This study aimed to carry out a comprehensive analysis documenting the risk of incidence of subsequent haematological malignancies. The Czech National Cancer Registry was the main data source, containing records of 126,822 haematological malignancies diagnosed in the period 1977–2016. Subsequent haematological malignancies were identified according to IACR rules. Joinpoint regression was employed to assess the time trends. The risk of development of subsequent haematological malignancy was evaluated by the standardised incidence ratio. The Kaplan–Meier curves were used to assess the differences in survival. Age-standardised incidence of subsequent haematological malignancies increased from 0.5 in 1977 to 9.1 in 2016. In 1992, there was a significant change in the trend: a sharp increase by 7.7 % annually was revealed thereafter. The risk of development of a haematological malignancy was approximately 1.5 times higher in persons with history of any cancer than in the general Czech population. Patients with haematological malignancies – mainly myelodysplastic syndromes, polycythaemia vera and non-Hodgkin lymphoma – were shown to be at the highest risk of developing a subsequent haematological malignancy. While the median survival following a first haematological malignancy was 2.3 years, it was only 1.1 years for subsequent haematological malignancies (p < 0.001). Our study identified the highest-risk diagnoses in terms of development of subsequent haematological malignancy. The results might be useful to set up correctly follow-up procedures from which cancer patients could benefit.