Cancer Epidemiology 37 (2013) 803–806

Childhood cancer in Aden, Yemen

Iman Ali Ba-Saddik *

Paediatric Department, Faculty of Medicine and Health Sciences, University of Aden, Yemen

A R T I C L E I N F O

Article history:

Received 25 June 2012

Received in revised form 22 July 2013

Accepted 6 October 2013

Available online 6 November 2013

Keywords:

Childhood cancer

Leukaemia

Lymphoma

CNS tumour and bone tumours

A B S T R A C T

Background: Cancer in children is increasingly recognized as a major and growing health problem in

different developed and developing countries. In Yemen, it is still difficult to know the extent of cancer

and its determinants among children. This study was conducted to determine the magnitude of

childhood cancer in Aden and provide the preliminary baseline data by age and sex.

Methods: Basic epidemiologic data was retrieved from all paediatric cancer <15 years age registered in

Aden Caner Registry (ACR), Yemen, from 1997 to 2006.

Results: The results showed a total of 483 childhood cancers <15 years age comprising12.7% of all

registered malignancies with a male to female ratio of 1.5:1. The predominant age affected was 5–9 years

in (38.3%) children. The most frequent cancer among Yemeni children was leukaemia 160 (33.1%)

followed by lymphoma 152 (31.5%), CNS tumors 35 (7.2%) and bone tumours 25 (5.2%). An interesting

and unusual finding was the frequency of acute myeloid leukaemia twice more common in female

(66.7%) than male (33.3%). Lymphoma was the most common cancer in children >5 years. An interesting

comparison was the preponderance of non-Hodgkins’s lymphoma over Hodgkin’s disease (1.6:1)

stronger in female (3:1) than male (1.25:1). Medulloblastoma was the most common CNS tumour

followed by astrocytoma, an infrequent finding in childhood cancer. Osteosarcoma was the most

frequent bone tumour (male:female ratio of 1.8:1). A female preponderance was noticed in

chondrosarcoma that was not yet documented. The blastoma group was common in younger age

group. Retinoblastoma and nephroblastoma predominated in female while neuroblastoma, hepato-

blastoma and soft tissue sarcomas in male.

Conclusion: It is concluded that there is a lower frequency of childhood cancer in Aden when compared

with developed countries. It may explained by the fact that a large number of childhood cancers remain

undiagnosed due to limitations of diagnostic facilities or under registration. Central paediatric hospitals

should be provided with essential diagnostic and therapeutic services that should be freely available to

all children with cancer.

� 2013 Elsevier Ltd. All rights reserved.

Contents lists available at ScienceDirect

Cancer EpidemiologyThe International Journal of Cancer Epidemiology, Detection, and Prevention

jou r nal h o mep age: w ww.c an cer ep idem io log y.n et

1. Introduction

Cancer is a significant cause of ill health and death amongchildren. Approximately one of every 500 children will developcancer between birth and the age of 15 years [1–3]. Cancerincidence varies from 100 to 180 per million children under 15years of age [4,5]. Paediatric cancer differs from adult malignanciesin their nature, distribution and prognosis [6]. The distribution ofcases by tumour sites varies with age during childhood [7]. Manydeveloping countries documented cancer to be substantiallyaffecting more male than female [8].

Leukaemia, the most common childhood cancer, account forabout one-third of paediatric malignancies [9,10]. Brain tumoursare second only to leukaemia as the most prevalent solid tumoursin this age group [11]. Lymphoma is reported to be the third most

* Tel.: +967 2 232997; fax: +967 2 221703.

E-mail addresses: imanmakki@gmail.com, iman_makki@hotmail.com

1877-7821/$ – see front matter � 2013 Elsevier Ltd. All rights reserved.

http://dx.doi.org/10.1016/j.canep.2013.10.001

common cancer in children in industrialized countries [12,13]. Inequatorial Africa, 50% of childhood cancers are lymphomas a resultof the very high incidence of Burkitt’s lymphomas [6,14].

In Yemen cancer has become a major growing health problem.Little is known about the cancer incidence in less economicallydeveloped countries and with a view to providing insight welooked at data from the Aden Cancer Registry, Yemen. This studywas conducted with the main objectives to describe the problem ofcancer and to assess the different types of cancer by agedistribution and sex among Yemeni children.

2. Patients and methods

The Aden Cancer Registry Centre (ACR) established in 1997 is apopulation based registry covering the four main governorates inAden with a population of around 2 million (MOPIC, 2005) [16].This centre collects and registers the epidemiological data ofpatients with cancer from public and private hospitals, diagnosticcentres and abroad treatment archives at Aden. The collected data

I.A. Ba-Saddik / Cancer Epidemiology 37 (2013) 803–806804

is entered to the computerized package Can Reg-4 and revised formonitoring any duplication or incompleteness. Classification andcoding of the neoplasm are carried out according to the ICD-O andICD-10.

In this study the basic epidemiologic data was retrieved fromthe records of patients with cancer <15 years of age registered inACR during January 1997 through December 2006. Analysisincluded identification of the patient, demographic characteristics,sex, age and year of diagnosis, site, morphology, histology andtopography of cancer and place of residence. The different types ofCancer were grouped into 12 major diagnostic groups according tothe International Classification of Childhood Cancer (ICCC) [15,17].Data were entered into computer database SPSS Version 15 forwindows. Statistical analysis included quantitative descriptiveanalysis and summary statistics for describing the frequency ofdiagnostic group and subgroups of childhood cancer. Quantitativeanalysis of the studied variables included Chi squares, Fischer exacttest and rates stratified by gender and age.

3. Results

A total of 483 childhood cancers of both sexes less than 15 yearsof age comprising 12.7% of all malignancies (3817) were registeredat the Aden Cancer Registry from January 1997 through December2006. Male comprised 288 (59.6%) and female 195 (40.4%) with amale to female ratio of 1.5:1. The mean (SD) age was 6.8 (4.0) yearsand the predominant age group was 5–9 years in 185 (38.3%)followed by 0–4 years in 163 (33.7%) children. The most frequentcancer among children based on the ICCC was leukaemia 160(33.1%) followed by lymphoma 152 (31.5%) and central nervoussystem (CNS) tumours 35 (7.2%). Soft tissue sarcomas included 16(3.3%), renal tumours 15 (3.1%), retinoblastoma 13 (2.7%) andsympathetic nervous system (SNS) tumours 12 (2.5%) (Table 1).

Leukaemia and lymphomas were the most common cancers inall age groups. Leukaemia 56 (34.4%) ranked first within 0–4 yearsfollowed by lymphoma 39 (23.9%). In the 5–9 years group,lymphoma 75 (40.5%) was followed by leukaemia 66 (35.7%), andCNS tumours 10 (5.4%). At 10–14 years, leukaemia and lymphomasformed equal bulk of tumours each 38 (28.1%), followed by bonetumours 19 (14.1%) and CNS tumours 17 (12.6%). The differenttypes of childhood cancer and their distribution within the threeage groups was statistically significant (p = 0.001) (Table 1).

The common cancer types among boys in order of frequencywere lymphomas 101 (35.1%), leukaemia 89 (30.9%), CNS tumours22 (7.6%), bone tumours 14 (4.9%) and soft tissue sarcomas 12(4.2%). The most frequent cancer among girls in descending order

Table 1Distribution of cancer by age and sex according to the International Classification of C

ICCC diagnostic

group

Leukaemias Lymphomas CNS

tumours

SNS

tumours

Retinoblastoma

Demographic feature N (%)

Age group in years

0–4 yrs

163 (33.7)

56 (34.4) 39 (23.9) 8 (4.9) 6 (3.7) 9 (5.5)

5–9 yrs

185 (38.3)

66 (35.7) 75 (40.5) 10 (5.4) 5 (2.7) 4 (2.2)

10–14 yrs

135 (28.0)

38 (28.1) 38 (28.1) 17 (12.6) 1 (0.7) –

Sex

Male

288 (59.6)

89 (30.9) 101 (35.1) 22 (7.6) 8 (2.8) 6 (2.1)

Female

195 (40.4)

71 (36.4) 51 (26.2) 13 (6.7) 4 (2.1) 7 (3.6)

Total N (%) 160 (33.1) 152 (31.5) 35 (7.2) 12 (2.5) 13 (2.7)

p = 0.001 Difference between the diagnostic group of childhood cancer and age groups

was leukaemia 71 (36.4%), lymphomas 51 (26.2%), CNS tumours 13(6.7%), bone tumours 11 (5.6%) and renal tumours 8 (4.1%)(Table 1).

Acute lymphoblastic leukaemia (ALL) was more frequent inmale than female 69 (58%) versus 50 (42%)), while acute myeloidleukaemia (AML) was more common in female than male ((7(33.3%) versus 14 (66.7%)). The difference between the diagnosticgroups of leukaemia and sex was statistically significant (p = 0.04)(Table 2). All lymphomas were frequent in males. Non-Hodgkin’slymphoma (NHL) predominated over Hodgkin’s disease (HD) with1.6:1 ratio which was stronger in female (3:1) than male (1.25:1).CNS tumours was common in male except for astrocytoma infemales (66.7%) Bone osteosarcoma was more common in male(63.6%) but chodrosarcoma was frequent in females (83.3%).Retinoblastoma and nephroblastoma did not show any sexdifference. Skin cancer was common among females (80%). Fivefemales had breast cancer (Table 2).

4. Discussion

This is the first report of data on 483 Yemeni patients withchildhood cancer from January 1997 through December 2006taken from on-going registry of ACR constituting 12.7% of allmalignancies. It is comparable with reports from developingcountries (4.1–12.6%) [18,19]. A male to female ratio of 1.5:1 wassimilar to the trends in Africa and Asia but different from westerncountries [20–22]. This sex pattern difference may be due to theunderlying nature of the disease. But in Yemen with limitedmedical resources, it is still likely that females may be underdiagnosed and males may have better access to medical care thangirls.

It is reported that some variations occur in the different cancertypes due to climatic and geographical changes. In this study, thecancer distribution among Yemen children based on the ICCCshowed leukaemia to be the most common (33.1%) followed bylymphomas (31.5%) and CNS tumours (7.2%) similar to somedeveloping countries but different from Sudan and Nigeria withlymphomas the most common cancers [7,10–14,17,22–29].

In general, a variable age specific pattern of Yemeni childhoodcancer was documented with highest frequency of leukaemia atless than 4 years while lymphomas within 5–9 years of age. Equalfrequency of leukaemia and lymphomas were seen at 10–14yearsfollowed by bone tumours and CNS tumours similar to somereports [6,27]. There is likelihood that this difference in cancertrend may be explained by a high proportion of childhood cancerstill remains to be undiagnosed, the insufficient diagnostic

hildhood Cancer (ICCC), Aden 1997–2006.

Renal

tumours

Hepatic

tumours

Bone

tumours

Soft tissue

sarcomas

Germ cell

tumours

Carcinomas Others

8 (4.9) 3 (1.8) 3 (1.8) 8 (4.9) 1 (0.6) 18 (11) 4 (2.5)

6 (3.2) 1 (0.5) 3 (1.6) – 1 (0.5) 11 (5.9) 3 (1.6)

1 (0.7) – 19 (14.1) 8 (5.9) 1 (0.7) 10 (7.4) 2 (1.5)

7 (2.4) 3 (1.0) 14 (4.9) 12 (4.2) 1 (0.3) 20 (6.9) 5 (1.7)

8 (4.1) 1 (0.5) 11 (5.6) 4 (2.1) 2 (1.0) 19 (9.7) 4 (2.1)

15 (3.1) 4 (0.8) 25 (5.2) 16 (3.3) 3 (0.6) 39 (8.1) 9 (1.9)

.

Table 2Distribution of childhood cancer diagnostic group and subgroup by sex.

Diagnostic group and subgroup Frequency by group N (%) Sex

Male N (%) Female N(%)

I. Leukaemias 160 (100%) 89 (55.6%) 71 (44.4%)

IA. Acute lymphoblastic leukaemia 119 (74.4%) 69 (58%) 50 (42%)

IB. Acute non-lymphoblastic leukaemia 21 (13.1%) 7 (33.3%) 14 (66.7%)

IC. Chronic myeloid leukaemia 1 (0.6%) 1 (100%) –

ID. Other specific leukaemias 11 (6.9%) 5 (45.5%) 6 (54.5%)

IE. Nonspecific leukaemias 8 (5%) 7 (87.5%) 1 (12.5%)

II. Lymphomas 152 (100%) 101 (66.4%) 51 (33.6%)

IIA. Hodgkin disease 58 (38.2%) 45 (77.6%) 13 (22.4%)

IIB. Non-Hodgkin lymphoma 72 (47.4%) 43 (59.7%) 29 (40.3%)

IIC. Burkitt lymphoma 12 (7.9%) 6 (50%) 6 (50%)

IID. Nonspecific lymphomas 10 (6.6%) 7 (70%) 3 (30%)

III. Central nervous system tumours 35 (100%) 22 (62.9%) 13 (37.1%)

IIIA. Ependymoma 1 (2.7%) – 1(100%)

IIIB. Astrocytoma 6 (17.2%) 2 (33.3%) 4 (66.7%)

IIIC. Primitive neuroectodermal tumours 3 (8.6%) 3 (100%) –

IIID. Other gliomas 5 (14.3%) 3 (60%) 2 (40%)

IIIE. Medulloblastoma 10 (28.6%) 6 (60%) 4 (40%)

IIIF. Others neoplasms 10 (28.6%) 8 (80%) 2 (20%)

IV. Symphatetic nervous system tumours 12 (100%) 8 (66.7%) 4 (33.3.%)

IVA. Neuroblastoma 9 (75%) 6 (66.7%) 3 (33.3%)

IVB. Neuroepithelioma 3 (25%) 2 (66.7%) 1 (33.3%)

V. Retinoblastoma 13 (100%) 6 (46.2%) 7 (53.8%)

V1. Retinoblastoma 10 (76.9%) 5 (50%) 5 (50%)

V2. Differentiated retinoblastoma 2 (15.4%) 1 (50%) 1 (50%)

V3. Undifferentiated retinoblastoma 1 (7.7%) – 1 (100%)

VI. Renal tumours 15 (100%) 7(46.7%) 8 (53.3%)

VIA. Nephroblastoma 14 (93.3%) 7 (50%) 7 (50%)

VIB. Renal carcinoma 1 (6.7%) – 1 (100%)

VII. Hepatic tumours 4 (100%) 3 (75%) 1 (25%)

VIIA. Hepatoblastoma 3 (75%) 2 (66.7%) 1 (33.3%)

VIIB1. Hepatic carcinoma 1 (25%) 1 –

VIII. Bone tumours 25 (100%) 14 (56%) 11 (44%)

VIIIA. Osteosarcoma 11 (44%) 7 (63.6%) 4 (36.4%)

VIIIB. Chondrosarcoma 6 (24%) 1 (16.7%) 5 (83.3%)

VIIIC. Ewing sarcoma 4 (16%) 2 (50%) 2 (50%)

VIIID. Other specific malignant tumours 4 (16%) 4 (100%) –

IX. Soft-tissue sarcomas 18 (100%) 13 (72.2%) 5 (27.8%)

IXA. Rhabdomyosarcoma 14 (77.8%) 9 (64.3%) 5 (35.7%)

IXB. Fibrosarcoma, neurofibrosarcoma 3 (16.7%) 3 –

IXD. Others 1 (5.6%) 1 –

X. Germ cell tumours 2 (100%) – 2 (100%)

XA Non-gonadal germ cell tumours 1 (50%) – 1 (100%)

XB Gonadal germ cell tumours 1 (50%) – 1 (100%)

XI. Carcinomas 39 (100%) 19 (48.7%) 20 (51.3%)

XIA. Adrenocortical carcinoma 4 (10.3%) 2 (50%) 2 (50%)

XIB. Thyroid carcinoma 3 (7.7%) 3 (100%) –

XIC. Nasopharyngeal carcinoma 10 (25.6%) 6 (60%) 4 (40%)

XIE. Skin carcinoma 6 (15.4%) 1 (16.7%) 5 (83.3%)

Breast carcinoma 5 (12.8%) – 5 (100%)

XIF. Other and unspecified carcinomas 11 (28.2%) 7 (63.6%) 4 (36.4%)

XII. Unspecified malignant neoplasm 9 (100%) 6 (66.7%) 3 (33.3%)

XIIA. Other specified malignant tumours 4 (44.4%) 3 (75%) 1 (25%)

XIIB. Other unspecified malignant tumours 5 (55.6%) 3 (60%) 2 (40%)

I.A. Ba-Saddik / Cancer Epidemiology 37 (2013) 803–806 805

facilities for some cancers as CNS tumours, or under registration inthe system of ACR.

Regarding sex distribution in childhood cancer, male predo-minated female in ALL that is similar to other reports [18,30]. Butan interesting finding in this study was the high frequency of AMLin female than male (66.7% versus 33.3%) not yet been reported tothe best of my knowledge [10,18]. Although lymphoma was morecommon in males than females more than 5 years of age similar tointernational trends, it was observed there was a preponderance ofNHL over HD which was stronger in female than male [21,24].

Burkitt’s lymphoma was equal in both sexes. In contrast to otherpublished reports, there was a low frequency of CNS tumours withmedulloblastoma the most common followed by astrocytoma[3,7,9,18]. Hence, better diagnostic facilities must be available toassess the frequency of CNS tumours in Yemen.

Osteosarcoma was the common bone tumour in males butchondrosarcoma showed a female preponderance, while theblastoma group was frequent in younger age groups [7,9,18,22].

Moreover, data on childhood cancer in Yemen is limited andmaybe underestimated. The results in this paper do not represent

I.A. Ba-Saddik / Cancer Epidemiology 37 (2013) 803–806806

all cancer cases in Aden but correspond to the best achievementsso far in this respect. The lower frequency of childhood cancer inAden when compared with neighbouring countries is due to a largenumber of childhood cancers that remain undiagnosed due tolimitations of diagnostic facilities and under registration. Somepatients with cancer might be diagnosed and treated outsideYemen. Therefore, all children with cancer from public and privatehospitals and polyclinics need to be reported by concernedphysicians to the ACR. It is also of paramount importance forthe Ministry of Health to provide the central paediatric hospitalswith essential diagnostic and treatment strategies that should befreely available and accessible to all children with cancer.

Conflict of interest

There is no conflict of interest to declare.

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