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 Table of Contents  
Year : 2020  |  Volume : 4  |  Issue : 1  |  Page : 1-7

Epidemiology of Gastrointestinal Malignancies in Nigeria:Port Harcourt Cancer Registry Study

1 Department of Anatomical Pathology and Cancer Registry Unit, University of Port Harcourt Teaching Hospital, Port Harcourt, Rivers State, Nigeria
2 Department of General Surgery (Endoscopy and Minimal Access Surgery Unit), University of Port Harcourt Teaching Hospital, Port Harcourt, Rivers State, Nigeria

Date of Submission22-May-2019
Date of Decision29-Nov-2019
Date of Acceptance07-Jan-2020
Date of Web Publication20-Apr-2020

Correspondence Address:
Dr. Christopher Chinedu Obiorah
Department of Anatomical Pathology and Cancer Registry Unit, University of Port Harcourt Teaching Hospital, Port Harcourt, Rivers State
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/oji.oji_30_19

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Background: Undocumented observations suggest a rising incidence of gastrointestinal tract cancers (GITc) among urban dwellers in Nigeria. Aim: The aim is to report on the incidence and clinic-pathological characteristics of GITc in Port Harcourt and its environs. Materials and Methods: Clinical, pathological, and demographic information on cancer patients obtained from various hospitals, radiology centers, and pathology laboratories within Port Harcourt and Obio-Akpor local government areas of Rivers state between 2008 and 2017 were reviewed. The information was coded using the International Classification of Diseases for Oncology, 3rd Edition and stored in Canreg 4 software in the Port Harcourt cancer registry. Results: GITc constituted the third-most common systemic cancers consisting of 12.2% (328 cases) with a male-to-female ratio of 1.05:1. The annual age-standardized rate ranged between 1.1–21.6/100,000 for females and 1.8–15.9/100,000 for males, with the highest rate recorded in 2017. The mean age was 51.2 ± 15.8 years with bimodal peak age groups of 50–54 and 55–59 years. The most common sites for GITc were colorectal followed by the liver and stomach consisting of 44.5%, 16.5%, and 15.2% of cases, respectively. Epithelial malignancies, i.e., carcinomas markedly predominated over malignancies of other cell types such as mesenchymal cell malignancies, lymphoreticular cell malignancies, and germ cell malignancies and constituted 92.4% of total GITc. Conclusion: GITc is posing a public health challenge in Port Harcourt and environs. A government-sponsored health plan on cancer control, including awareness campaigns on the adoption of more healthy lifestyles, hepatitis B vaccination, colonoscopy screening with prompt treatment, is advocated.

Keywords: Cancer registry, epidemiology, gastrointestinal tract, Port Harcourt

How to cite this article:
Obiorah CC, Ray-Offor E. Epidemiology of Gastrointestinal Malignancies in Nigeria:Port Harcourt Cancer Registry Study. Oncol J India 2020;4:1-7

How to cite this URL:
Obiorah CC, Ray-Offor E. Epidemiology of Gastrointestinal Malignancies in Nigeria:Port Harcourt Cancer Registry Study. Oncol J India [serial online] 2020 [cited 2020 Aug 13];4:1-7. Available from: http://www.ojionline.org/text.asp?2020/4/1/1/282832

  Introduction Top

Cancer will be a leading cause of morbidity and mortality in the world by 2030, and it is projected that there will be about 26 million new cancer cases and 17 million cancer deaths per year.[1],[2] Gastrointestinal tract cancers (GITc) which include: gastric cancer (GC), colorectal cancer (CRC), hepatocellular carcinoma, esophageal cancer (EC), pancreatic cancer, and gall bladder cancer (GBC) are responsible for more cancer-related deaths than any other system in the body.[3],[4] They, therefore, constitute a leading health problem in the world and their burden is increasing in many countries.[5] As at 1975, low- and middle-income countries accounted for about half (51%) of all cancers worldwide; this proportion increased to 55% in 2007 and is projected to reach 61% by 2050, despite the bedeviling poor socioeconomic issues that limit access to quality healthcare in these nations.[6] This shift in the burden of cancers is largely attributable to the increasing incidence of some cancers which had hitherto been uncommon in the underdeveloped nations and common among the developed nations, especially GITc. Undocumented observations indicate a possible rise in the incidence of GITc in urban dwellers in Nigeria. The entrenchment of modifiable risk factors such as smoking, obesity, physical inactivity, and poor nutrition among the underdeveloped nations, including Nigeria largely accounts for the shift in the cancer burden.[2] Recent studies indicate that excess adiposity is a risk factor for several cancers of the gastrointestinal system.[7] A review study by Chukwuonye et al. documented the prevalence of overweight and obesity among Nigerians as ranging between 20.3%–35.1% and 8.1%–22.2%, respectively.[8]

Fortunately, some GITc is amenable to screening, prevention, and early treatment, which potentially reduce the overall burden. This is exemplified by the reported decrease in the incidence of CRC in the United States since the mid-1980s because of the application of preventive measures and screening.[9] There is a paucity of research publications on the incidence of GITc in our environment. The few published articles are limited in scope and based on restricted individual practice and case series. This cancer study is population-based and presents the incidence and clinic-pathological characteristics of GITc in Port Harcourt and its environs.

  Materials and Methods Top

The data covered the period between January 1, 2008, and December 31, 2017, for the two most populous local government areas of Rivers State of Nigeria, i.e., Port Harcourt city and Obio-Akpor, which together constitute the geographic capital of Rivers state. These council areas were upland by topography and had mixed rural and urban settlement patterns. The joint population of the areas in the 2006 census was 1,000,908 (19.3% of Rivers state population).[10] The registry was domiciled in the University of Port Harcourt Teaching Hospital (UPTH) Port Harcourt. In general, cancer cases were defined by histology, cytology, and hematology smear reports as well as patients' physical examination findings, clinical impressions, and autopsy/death certificate review findings. Notification sources were as follows: outpatients' departments and wards of the tertiary, general, and private hospitals that are involved in the diagnosis and treatment of cancer patients and operating within Port Harcourt and Obio-Akpor council areas. Other notifications sources were privately owned and operated pathology laboratories and radiology centers. At the notification centers, cases were documented onto the prototype register of the Nigerian national system on the cancer registry and later transcribed and stored electronically using the Canreg 4 software (IARC, Lyon, France). The International Classification of Diseases for Oncology, 3rd Edition, formed the basis of classification and coding of cases.[9] As much as possible, completeness of the case identification and prevention of duplication was ensured through regular visits to case notification centers and reviews of the electronic data. The latter was exported to SPSS version 23. SPSS Chicago, Illinois, U.S.A. used for the analysis. Cancer sites included were: esophagus, stomach, small intestine, colon, rectum, anus, liver, gall bladder, and pancreas. Of interest in every case were the dates of incidence, patients' sociodemographic features, including the level of education attained, occupation, place of abode, gender, and age. Furthermore, information on topography, morphology, and degree of differentiation was sought. The age-standardized rates (ASRs)/100,000 of the population at 5-year intervals were calculated.

Ethical clearance for this study was granted by the University of Port Teaching Hospital research ethical committee (UPTH/ADM/90/S. II/VOL. XI/714).

  Results Top

GITc constituted 328 (12.2%) of the 2682 cancers recorded in the 10-year study period. They were the third most common systemic cancers after the genital tract system (38.3%) and breast (29%) [Table 1]. The annual ASR ranged between 1.1–21.6/100,000 for females and 1.8–15.9/100,000 for males. The combined ASR for both males and females ranged between 1.8 and 18.1/100,000, and the highest ASR for both genders was recorded in 2017. While the overall mean age of all cancers was 51.9 ± 17.7 years that of GITc was 51.2 ± 15.8 years. The age range for GITc was 2–87 years. The majority of the cases, i.e., 209 (63.7%) were older than 45 years (106 males and 103 females). Whereas 119 cases (36.3%) were 45 years and below - (62 males, 57 females). The least affected age group was 15–19 with a case (0.3%), whereas 50–54 and 55–59 constituted bimodal peaks with 44 cases (13.4%) each [Table 2]. Overall, children and adolescents aged 1–19 years constituted only 1.8% of the patients. The cancers predominated among those older than 45 years (especially GBC where all the patients were older than 45 years) except cancers of the ampulla of Vater where patients 45 years and younger constituted 75% [Table 3].
Table 1: Systemic distribution of cancers

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Table 2: Age and gender distribution among GITc

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Table 3: Cancer sites with age distribution at below and above 45 years

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Altogether, GITc was composed of 168 males and 160 females with colorectal carcinoma (CRC) constituting the majority 146 cases (44.5%), followed by liver cancers with 54 cases (16.5%) and stomach with 50 cases (15.2%) [Table 3]. Although the least no of cases were recorded in 2008, i.e., 7 cases (2.1%) and the highest in 2017, i.e., 106 cases (32.3%), the trend appeared generally undulating but with an overall upward skew [Figure 1]. Grading of the cancers showed that poorly and well-differentiated cases were almost equal in overall incidence composing 39.3% and 39.6% of cases, respectively, but there is significant variation on the degree of differentiation among the individual cancer sites (P = 0.02). For example, 41.1% of CRC were poorly differentiated and 35.6% were well-differentiated, whereas 24.1% of liver cancers were poorly differentiated and 57.4% were well-differentiated [Table 4].
Figure 1: Trend of GITc and gender distribution

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Table 4: Cancer site and tumor differentiation

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A review of the morphologic characteristics showed a marked predominance of malignancies of epithelial cells, i.e., carcinomas, over malignancies of other cell types such as connective tissue cells, i.e., mesenchymal tumors (sarcomas), cells of lymphoreticular origin like lymphomas as well as those of germ cell origin like yolk sac tumors, etc., [Table 5].
Table 5: Frequency distribution of topography and morphology

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Sociodemographic indicators showed that the local indigenous tribes of Rivers state predominated over the others and was followed by the Ibo tribe (62.5% vs. 27.7%, respectively), while civil servants (44.2%) outnumbered the self-employed (23.2%) and the retired (15.5%), among the patients. Furthermore, incidence increased with the level of education, with those who attained a tertiary level of education constituting 53%. The urban dwellers were more involved in GITc than the rural dwellers, i.e., 72.3% versus 27.7% [Table 6].
Table 6: Sociodemographics of GITc patients

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  Discussion Top

Local, national, and international cancer control programs are imperative for the reduction of cancer morbidity and mortality while improving the quality of life of those already afflicted with the disease, using available resources.[11] Planning and initiating such programs are dependent on good clinic-pathological information provided by a population-based cancer registry. This study provides a framework for the initiation of a sustainable control program for GITc. It shows that GITc constituted 12.2% and the third-most common systemic cancer in our environment with the annual ASR ranging up to 21.6/100,000 for females and 15.9/100,000 for males. The combined ASR for both males and females peaked at 18.1/100,000. The highest ASR for both genders was recorded in 2017 and became the figure we refer to, being the latest. The undulating incidence trend is due to the wide variation in the numbers of recorded cancer cases across the years, with the least number recorded in 2008 and the highest number in 2017. This variation obviously reflects the difficulties in identifying and obtaining information on cancer patients in our environment, consistent with literature documentation that the major challenge of cancer registration among the nations of Sub-Saharan Africa is the identification and registration of all new cases of cancer.[12],[13] Since generally, cancer patients are documented only when they visit hospitals, health centers, clinics and laboratories, in our environment where owing to poverty, ignorance and superstitious beliefs, many patients present only to unorthodox healing centers such as herbal homes and religious centers, the cancer data may not fully represent the true incidence. Furthermore, inconsistency and the absence of dedicated field staff remain an impediment to the consistency of data gathering. These then highlight the need for institutional and government support for cancer registration in Port Harcourt, especially given the reported hydrocarbon pollution of some catchment environment of our registry.[14]

Although the 12.2% GITc proportion recorded in this work is <20% and 38% reported in the USA and Iran, respectively, and the 44% mortality reported in Chile, it is noteworthy that GITc as the third-most common systemic cancer in our environment deserves to be planned for.[15],[16],[17] The only published study on GITc, in Nigeria at our disposal conducted in Zaria (Northern Nigeria) was silent on the proportional composition of GITc and was not cancer registry based.[18]

The range and mean ages of our patients were 2–87 years and 51.2 years. This is below the 63.8 years reported in a similar provincial study in Iran.[19] The lower life expectancy in Nigeria may account for the lower mean age observed. Although all age groups are involved, children and adolescents <19 years constituted only 1.8%, indicating the rarity of these malignancies among children and adolescents. Furthermore, about 64% of the patients were >45 years further lays credence that age is a factor in the incidence. In general, cancers are age-related and the global increase in cancer burden is propelled significantly by growth and aging of populations.[2] Data from the American cancer society indicate that 87% of cancers in the United States are diagnosed in people 50 years or older.[20] Interestingly, the population structure of the host state-Rivers shows the marked predominance of children and young adults with people who are 45 years and below constituting about 87%, whereas those aged >45 years constitute only 13%.[10] Thus, other modifiable risk factors may likely hold sway as risks for GITc in our locality than age. Consistent with this, other risk factors such as overweight and obesity have been identified for GITc.[7] These factors are becoming public health concerns in Nigeria currently.[8]

The proportion of females in this study is relatively high since previous studies showed a clear predominance of males in GITc unlike ours that showed almost an equal gender ratio (1.1:1).[3],[4],[5],[6] This reflects demographic variation in the epidemiology of GITc.

Colorectal carcinoma (CRC) predominated with 44.5%, followed by liver and stomach cancers with 16.5% with 15.2%, respectively. This order contrasts with the reports from other geographic regions of the world, especially Asia and China, regions with high GITc incidence where esophageal and GCs are very high. The area stretching from Northern Iran through the Central Asian republics to North-Central China is referred to as the “esophageal cancer belt,” where ECs exponentially predominates the other composite sites of GITc followed by stomach cancer.[21],[22] Contrary to this belt, the United States, like our case has a predominance of CRC among GITc constituting the third most common cancers in males and females.[20] Demographic dynamics among Nigerians including the adoption of Western lifestyles and diet, cigarette smoking, and physical inactivity may be responsible for the prominence of CRC which was hitherto described as a rare disease among Nigerians some 40 years back.[23] Little wonder that Maiyaki and Garbati and Adedoyin and Adesoye stated in their separate works that Nigeria is undergoing epidemiological transition ushered in by globalization, changing demographics dynamics, affluence, and pattern of food consumption.[24],[25] Public health measures that address the aforementioned modifiable lifestyle risk factors like the maintenance of healthy body weight, physical fitness, minimal consumption of red and processed meat and alcohol, and avoidance of smoking as well as regular colonoscopy screening for CRC, needs to be entrenched among the psyche of our populace.[26],[27] In the United States, the incidence of CRC was reported to have been significantly reduced over the years, especially among those 50 years and older as a consequence of screening and removal of precancerous adenomas.[28]

Liver cancer was a cause for concern in this study constituting the second commonest topography. Since hepatitis B virus (HBV) and hepatitis C virus account for an estimated 32% of liver cancers in less developed countries, it stands to reason that the prevention and control of liver cancers can largely be achieved through public health measures like anti-HBV vaccination, safe medical practices, healthy lifestyle choices, abstinence from smoking and good control of type 2 diabetes.[29],[30] The efficacy of the HBV vaccination was alluded to in the more than 80% decline in liver cancer incidence rate among young adults in Taiwan following the general childhood HBV vaccination program that began in 1984.[31]

The bane of gastric carcinoma is the very late presentation largely because of nonroutine utilization of endoscopy in our environment, stemming from inadequate technically trained workforce, lack of awareness, and entrenched poverty among most of the populace. Thus, adopting preventive strategies which include: reducing intake of foods preserved by salting or smoking; increasing consumption of fresh fruits and vegetables; avoidance of active or passive smoking; and reduction in the prevalence of Helicobacter pylori infection through the improvement of socioeconomic conditions, routine screen testing and treatment will help reduce the burden.[32] For esophageal carcinoma, the entrenchment of healthy lifestyles that abort overweight and obesity, including regular intake of fruits and vegetables, as well as the avoidance of smoking and drinking of beverages at high temperatures, are recommended preventive public health measures.[33],[34]

The array of morphologic types of malignancies is wide ranging from carcinomas, lymphomas, sarcomas, hepatoblastomas, and yolk sac tumors with adenocarcinoma markedly predominating. This wide spectrum is because both primary and metastatic tumors were involved and the predominance of adenocarcinoma is similar to the reports of other investigators.[5],[6],[17],[19]

The predominance of the GITc in the indigenous tribes of Rivers state over the Ibos (62.5% vs. 27.7%), and the rest may reflect the ethnic habitation distribution of the denominator local government areas of Port Harcourt and Obio-Akpor. It may also be a pointer towards ethnic variation in cancer-predisposing lifestyles. In the United States, Garza et al. showed that gastrointestinal cancers, particularly liver cancer, are more frequent in the Mexican American population than other ethnic groups in the U.S.[35]

Globally, cancer is said to have the most devastating economic impact than any other disease from its morbidity, disability, and mortality.[20] Our study further shows that GITc constitutes an enormous toll on the economy of River state in particular and Nigeria in general, as the majority of the patients (67.4%) were active players in the economy (civil servants and self-employed at the time of their diagnoses). Local studies to estimate the economic burden of cancer in our environment need to be carried out. For example, in 2008, the American Cancer Society estimated that the global economic burden resulting from premature cancer-related deaths and associated disabilities of survivors was $895 billion; GC incidence was the second-highest cause of such premature deaths and disabilities.[20] It is indeed compelling on the local authorities and donor agencies in Rivers State and Nigeria to understand that addressing cancer insurgency in the state will not only save lives but save money and grow the economy. That the incidence of GITc increased with the level of educational attainment and urban dwelling is consistent with general cancer research findings that cancer incidence increases with human development index and urban dwelling.[36],[37],[38]

This work is limited by the inconsistent logistic support and zero funding of the cancer registry as well as the ad-hoc deployment of field staff by the hospital management over the past years, which may result in under reportage of cases. Furthermore, the patronages of unorthodox and unregistered treatment centers such as religious and herbal homes and even nonpresentation of some patients on account of poverty and nonaffordability of required specialist services exclude those cases.

  Conclusion Top

There is a rapid rise in the incidence of GITc in recent years, and it is the third-most common systemic cancer in our environment with an almost even sex distribution. A government-sponsored health plan of a sustainable cancer control program, including regular HBV vaccination, colonoscopy screening, an awareness campaign on the adoption of more healthy lifestyles, and prompt treatment is well deserved.

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Conflicts of interest

There are no conflicts of interest.

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  [Figure 1]

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]


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