ABSTRACT
BACKGROUND Bladder cancer is a common urologic cancer and is ranked as the 9 th
most frequent malignancy and the 13 th most fatal globally. In Nigeria, the incidence, histologic types, age and sex distribution vary among various published reports. This ten year retrospective histopathological review was carried out to evaluate the frequency of and determine the age and sex distribution of various histologic types of bladder cancer received in the Histopathology department of Aminu Kano Teaching Hospital from January 1, 2002 to December 31, 2011, as well as compare the findings with previous studies in Nigeria, Africa and the rest of the world.
MATERIALS AND METHOD Laboratory request forms and duplicate copies of histology reports were retrieved and relevant clinical information such as age, sex and
histological types were extracted. Haematoxylin and eosin stained slides were reviewed and evaluated.
RESULTS A total of 247 bladder cancer cases were received during this period, 12 of which had incomplete data, leaving 235 cases for this study. There were 204 cases from males (86.8%) and 31 from females (13.2%) giving a male to female ratio 6.5:1. The ages ranged from 10 months to 75 years with a mean age of presentation at 45.5 years. The most common variant of bladder cancer was urothelial carcinoma with 117 cases (49.8%) followed by squamous cell carcinoma with 102 cases (43.4%). Urothelial carcinoma had a mean age of presentation at 51.5 years with peak incidence in the 6 th decade of life and male to female ratio of 8.7:1. Squamous cell carcinoma had a mean age of presentation at 38.6 years with peak incidence in the 5 th decade with male to female ratio of 5:1. Thirteen cases of adenocarcinoma were recorded in this study. All of them were seen in males and their ages ranged from 40-89 years with a mean age of 53.7 years. One case each of embryonal rhabdomyosarcoma, angiosarcoma and pleomorphic rhabdomyosarcoma was recorded in this study.
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CONCLUSION
This study shows that bladder cancer is a common malignancy in Kano with a marked male preponderance. Urothelial carcinoma is the most common histological variant of bladder cancer in this study, a reverse of the finding of an earlier study on bladder cancers in Kano which found squamous cell carcinoma to be the most common variant. This changing histological profile of bladder cancer is, however, consistent with some local and international studies.
CHAPTER ONE
INTRODUCTION
The bladder is a distensible hollow pelvic organ for temporary storage of urine pending voiding. Malignancies of this organ can arise from any of its component tissues, but like other viscera they mostly arise from its epithelial lining. Hence urothelial and squamous carcinomas are by far the commonest types of bladder cancer. Globally, bladder cancer is the 9th most frequent malignancy and the 13th most fatal. 1, 2 The incidence varies around the world with high rates in schistosomiasis endemic zones such as Egypt, Zambia,
Sudan and parts of Northern Nigeria. 3,4 5 ,6 High rates have also been documented in several southern and eastern European countries. 7,8
Here in Nigeria, the incidence appears to be higher in the North than in the South. In Lagos
, bladder cancer comprised just 0.86%
of all malignancies, while the same malignancy accounted for 6.2% of cancers in Kano.
Similar higher rates have been reported from studies in Maiduguri and Sokoto, presumably because of the higher endemicity of Schistosoma haematobium in the Northern Nigeria occasioned by widespread use of irrigation dams. 10,11
In non-schistosoma endemic parts of the world, other aetiological factors are more important, notably chemical carcinogens such as heterocyclic hydrocarbons in tobacco smoke, drugs like cyclophosphamide and occupational exposure of textile/dye workers to β-naphtylamine. 12,13,14,15 There are also significant global differences in histologic types and age distribution, with higher prevalence of squamous carcinomas in schistosomiasis endemic zones where bladder cancer peaks in younger age group; fifth decade, while urothelial carcinoma predominates in non-schistosomiasis zones afflicting patients in 7th decade of life. 16, 17, 18
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Here in Nigeria, findings vary among various published reports from different parts of the country. 10,11,12,19 It is therefore pertinent to document and evaluate the pattern in our local.
RATIONALE FOR STUDY Over a decade ago, an earlier study in Kano documented bladder cancer as the second most prevalent visceral malignancy among males.
Only prostate cancer was more frequent. These findings were largely corroborated by a cancer registry data which documented vesical cancer as the 6th commonest malignancy in Kano. This study endeavours to update our knowledge of bladder cancer in Kano, particularly as the earlier study over a decade ago in the early formative years of Aminu Kano Teaching Hospital – only reviewed 60 cases. Such small sample size is of low statistical significance for a catchment population of over 20 million (Kano, Katsina, Jigawa).
The hospital has since grown exponentially to become a major urological referral centre in the north west of Nigeria with a patient turnover that has increased 10 fold.
AIMS AND OBJECTIVES
This study intends to evaluate the histopathological pattern of bladder cancers diagnosed at the Pathology department of Aminu Kano Teaching Hospital (AKTH), Kano. Specific objectives include: 1. To determine the age and sex distribution of bladder malignancies. 2. To determine the relative frequency of the different histological types of bladder cancer.
3. To compare data from this study with other bladder cancer studies around the world.
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