Urinary bladder cancer is the sixth most common cancer worldwide, and presents as the second most common malignancy affecting the genitourinary tract after prostate cancer and represents a heterogeneous group of neoplasms.1
Research on urinary bladder cancer in Middle Eastern countries is scarce, and markedly so in Yemen. Ninety-nine percent of bladder neoplasms in this research arose from the epithelium; the most common subtypes were urothelium neoplasms which account for 78% of cases, and SCC which represents 17% of cases. The observed figure for urothelial neoplasms (78%) was markedly similar with that reported from neighboring Saudi Arabia (77%).8
However, lower figures have been reported in Africa; Nigeria (42%),9
and Tanzania (28%).10
In developed countries, over 90% of the bladder cancer cases are urothelium neoplasms with SCC, adenocarcinoma, and rare types of bladder cancer comprising the remaining 10%.11
In the USA, a high frequency of urothelial neoplasms (98%) has been reported by Schned et al.2
In the current study, Squamous cell carcinoma accounted for 17%. However, considerable variability was noted in the prevalence of SCC of the bladder in different parts of the world. It accounted for only 1% of bladder cancers in England,11
and 7% in the United States,12
but as high as 75% in Egypt.13
Approximately 59% of SCC in this study were associated with chronic infection by schistosoma hematobium. An earlier study conducted in Egypt showed that around 80% of SCC were accompanied by chronic infection with schistosoma hematobium.14
Recently, transitional cell carcinoma has become the most frequent type encountered in Egypt due to the significant changes in the etiology of bladder cancer.15
Also, adenocarcinoma (primary bladder, urachal or metastatic) represents 3% of malignant bladder tumors in this study which is similar to what has been reported by other authors.16
In general, it may be said that while comparing the frequency of histological subtypes in the present study with others studies, a clear difference was observed. Such a divergence could be explained in terms of diagnostic approach and/or probably due to the combined effects of environmental and hereditary factors. Additionally, tobacco use is believed to be similarly spread worldwide and it may explain the overall increase in urothelium neoplasms in our patients. Both tumor grade and stage of urothelial carcinoma are highly correlated with recurrence, progression, and patient survival rates.2
The WHO/ISUP grading of urothelial neoplasms of the bladder is of great prognostic significance. The findings shown in reveal the distribution of urothelial neoplasm grading according to the WHO/ISUP criteria; carcinoma in situ (2%), papilloma (3%), PUNLMP (11%), PUC-LG (43%), PUC-HG (7%), and Non-PUC-HG (34%). In Jordan, Matalka et al.17
reported 60% of low grade and 40% of high grade. A recent report from the USA2
showed CIS, papilloma, PUNLMP, PUC-LG, PUC-HG and NPUC-HG to be 6%, 0.3%, 26%, 35%, 23%, and 10%, respectively. While in Australia, Samaratunga et al.18
reported 2% papilloma, 22% low malignant potential, 13% low grade, and 22% high grade carcinoma. The variation found between these results could be explained in terms of diagnostic approach and/or techniques applied, number of patients studied, as well as geographical and immunological differences.
The histological grading suffers from all the drawbacks of a subjective evaluation, especially when performed in biopsy material. Furthermore, the differences of a given neoplasm may vary from area to area, thus a cystoscopic biopsy may show a low-grade malignancy as opposed to what is present in the surgical specimen. The paucity of CIS cases in this study was due to the exception of the cases that were seen to be in association with conventional urothelial carcinoma and were especially common in high-grade lesions.
Also in this study, men are nearly 4 times more likely to be effected with bladder urothelial neoplasms than women. Worldwide, the male-to-female ratio ranges between 1:3 and 1:5.19,20
However, a higher ratio was documented in Jordan; 1:9.17
A marked male preponderance was seen in all types in this study as well as worldwide, probably because boys and men are more involved in agricultural and industrial activities making them more exposed to carcinogenic factors. The age of patients ranged from 12 to 95 years with a mean age of 59 years and most of the cases of urothelial neoplasms (70%) were present in patients aged over 51 years and in approximately 30% of younger adults and children. The frequency of urothelial neoplasms in Yemen is increased with increasing age, and a significant difference was observed among the age groups. In the current study, the cases involving younger adults and children showed urothelial neoplasms of predominantly low grade with a favorable clinical outcome, while high grade was encountered in older age groups. These findings are in accordance with those reported in other investigations.11,21
The youngest patient was a 12 year-old boy with urothelial papilloma. However, urothelial neoplasms in patients aged younger than 20 years are generally rare. Fine et al. identified 23 patients with urothelial neoplasms with a mean age of 13 years.21
However, since the current study was limited to recorded data, many difficulties were encountered in the interpretation of results due to incomplete information from patient history, staging and management of the neoplasms. This could not be denied as in all retrospective studies particularly in a country like Yemen, where the medical services are spanned among ministry of health and private hospitals. However, the figures obtained in this study are of significance in making acceptable conclusions on the national level of frequency of urinary bladder cancer.