Shahina Qureshi ( Pakistan Institute of Medical Sciences, Children’s Hospital, Islamabad. )
Childhood malignancies which were fatal about two decades ago are nearly all treatable, and almost half are curable. They differ in clinical behaviour, histology, and site of origin from adults. The most dramatic change in prognosis has been in acute lymphocytic leukaemia, which, today, is still the most common of all childhood malignancies1. Our experience with malignancies at the Children’s Hospital Islamabad, is discussed in this paper. The cases have been picked up from an average, daily out patient attendance, of 600/day and draw patients from the districts around Rawalpindi, Islamabad, Azad Kashmir, and other adjoining areas.
MATERIALS AND METHODS
Of 4363 patients admitted to the medical wards of Children\'s Hospital over a period of 2 years from October 1986 to October 1988, there were 104 (2.3%) cases of childhood malignancies. Seventy two patients were male and 32 females. The male/female ratio was 2.4:1. The relative frequency of tumours in our series is shown in Table I.
RESULTS AND COMMENTS
The distribution of major forms of childhood cancer varies in different age groups. Many tumours, especially those associated with chromosomal defects, have a peak incidence in children under 5 years of age2. In our series more than 50% of patients were under 6 years of age, with a peak incidence at 2-4 years. These comprised of children with acute lymphoblastic leukaemia, neuroblastoma, Wil’s, tumour and liver tumours. The peak incidence of acute lymphocytic leukaemia occurred at 3-5 years of age. This peak is seen in the western countries, but is absent in Africa and many developing nations3. The malignancies seen in children above 6 years of age, with a peak between 11-12 years, were, Hodgkins disease, central nervous system tumours, and bone tumours. The occurrence of tumours above 6 years has been related to environmental factors, for example, Epstein-Barr virus is linked to the development of non Hodgkins lymphoma4. In the United States and Britain, the overall incidence of pediatric malignancies is more frequent in males, by a ratio of approximately 1:2:1. 5 In our series it was also higher than, and almost double the number seen in females. A comparision of the frequency of tumours in our series with U.S. studies6 is shown in Table II.
According to the third national cancer survey in USA, leukaemias and lymphomas are the most common malignancies and constitute 44% of cancer in children5. Our studies show 47.2% incidence of leukaemias and lymphomas. This is followed by central nervous system and sympathetic nervous system tumours, which have a 26% incidence in both series. Liver tumours were the least frequent in both series, being 1.9% in CH study, and 1.1% in the US. Reports from the Far East show excessive number of liver tumours. These are similar to studies done by Pizzo at the National Cancer Institute in USA. 7 Acute leukaemias have a very high incidence of 38.5%. A high incidence of acute leukaemia has also been reported from Israel, Denmark, and Japan8 and a lower incidence from Nigeria9 and India10. . Workers from Nigeria showed a greater proportion of lymphomas, probably due to increased incidence of Burkitt’s lymphoma11. The tumour frequencies, different from western studies, were seen in neuroblastoma and retinoblastoma. Neuroblastoma, which has a high incidence in Western Europe and the US2, was not so common in our series (4.8%). Retinoblastoma had a high incidence of 6.7% compared to 2.7% in the US5.
Table III shows the frequency of selected tumours as compared to Wilm’s Tumours in different areas in Pakistan12. Wilm’s Tumour is used for comparision because it has an almost equal worldwide distribution. According to the Pakistan Medical Research Council study, CNS tumours and leukaemias were seen to be less frequent than lymphomas from all centers of Pakistan12. Retinoblastomas were more frequent in one study13, and lower in our series. This review is not all inclusive but represents many aspects of the epidemiology of childhood cancer.
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