Trends in Incidence of Haematological Malignancies in Kenya: 2000-2013

Abstract: Introduction: Haematological malignancies (HMs) are a rare and diverse group of malignancies accounting for 9% of cancers globally. These group of malignancies differ by age, sex, subtypes, morphology and geography. The burden and the patterns of diversity of HMs is poorly understood in low and middle-income countries including Kenya. Aim: To analyse the time trends of incidence of haematological malignancies in Kenya by broad subtypes from 2000–2013 and to compare differences in trends of HMs between Nairobi and Uasin Gishu counties for the period 2007-2013. Methods: A retrospective study including all HMs for all ages and sex diagnosed in the period of 2000-2013. Information used was from two population based cancer registries; Eldoret and Nairobi cancer registry. Crude incidence rates were directly standardized with the world population to obtain the age-standardized rates (ASR). Sex rate ratios (SRR) and incident rate ratios (IRR) were then calculated to compare the number of excess cases between sexes and counties. Ms Excel and STATA13 software were used to conduct a time trend analysis of haematological malignancies by broad subtypes of non-Hodgkin lymphoma (NHL), Hodgkin lymphoma (HL), myeloma and leukaemia. Using the estimated annual percentage change (APC), increase or decrease in trends of HMs was determined. Results: In Kenya, the mean age at diagnosis for all HMs was 32 years. NHL was the most commonly diagnosed HM in Kenya accounting for 43.6% of the cases. The main basis of diagnosis for NHL and HL cases was by cytology while for myeloma and leukaemia was by histology. A male excess was noted in the NHL, myeloma and leukaemia cases with an exemption of a female excess in the HL cases. Trends in incidence of HMs in Kenya increased by 9.8% with the myeloma subtype contributing greatly to the observed increase. By counties, Uasin Gishu county reported a higher number of HM cases per 100000 than Nairobi county (Uasin Gishu-97.6 per 100000 and Nairobi-69.9 per 100000). On the contrary, Nairobi marked a higher increase in trends of HMs than Uasin Gishu county. Conclusion: Trends of haematological malignancies are increasing in Kenya and special attention needs to be given to these under-reported group of malignancies. Finally, this study does support the dire need for a national cancer registry in the country.