|Year : 2014 | Volume
| Issue : 1 | Page : 16-19
Histopathological patterns of prostate cancer in an African population: A private practice experience
Gerald Dafe Forae, Jonathan Umezulike Aligbe
Department of Pathology, University of Benin Teaching Hospital, Ashamas Foundation Clinic, Benin City, Nigeria
|Date of Web Publication||7-Apr-2014|
Gerald Dafe Forae
Department of Pathology, University of Benin Teaching Hospital, Benin
Background: Prostatic cancer is the most common urological tumor seen in middle-aged and elderly men. It constitutes a source of morbidity and mortality in the adult male population. Aim: Highlight the frequency and histological types of prostatic cancer in a private practice in Benin-City, Southern Nigeria. Materials and Methods: Hematoxylin- and eosin-stained-slides of prostatic biopsies diagnosed at the Ashamas foundation clinic, Benin-City for 10 years were archived and studied. Request forms were scrutinized for clinical bio-data, diagnosis, and histological sections and slides were analyzed. Results: During this 10-year study, a total of 908 prostatic tumors and 226 urological malignancies were diagnosed. Among this, 214 were prostatic cancer. Prostatic cancer, therefore, constitutes 23.6% and 94.7% of all prostatic tumor and urological tumor, respectively. The peak age range was 70-79 years constituting 83 cases (38.8%) of all age group. The mean age for prostate cancer was 68 years ± 4.6 S.D. Prostatic adenocarcinoma accounted for 201 cases constituting 93.9% of prostatic cancer. A total of 53 cases (30.4%) had Gleason's score 2-4, 104 cases (59.8%) had Gleason's score 5-7, and 17 cases (9.8%) had Gleason's score 8-10. Conclusion: Prostate cancer is the most common tumor of the uro-genital system in males with majority as moderately differentiated prostatic adenocarcinoma having Gleason's score of 5-7.
Keywords: Gleason′s score, histopathology, prostatic cancer, private practice
|How to cite this article:|
Forae GD, Aligbe JU. Histopathological patterns of prostate cancer in an African population: A private practice experience. Trop J Med Res 2014;17:16-9
|How to cite this URL:|
Forae GD, Aligbe JU. Histopathological patterns of prostate cancer in an African population: A private practice experience. Trop J Med Res [serial online] 2014 [cited 2019 Jun 25];17:16-9. Available from: http://www.tjmrjournal.org/text.asp?2014/17/1/16/130176
| Introduction|| |
Prostate cancer has been a disease of antiquity in men. It was first described by an English surgeon called Adams about a century and a half ago.  Although, it is the most common cancer in men worldwide, it is commonly encountered in middle-aged and elderly males; however, it is rare in men before the age of 40 years.  Globally, there is an epidemiological increase the incidence of prostate cancer. Nevertheless, it is still under reported due to lack of adequate data from most developing countries. , Reports have it that there is ethnic variation in its prevalence. It is most common in African-American and the Scandinavians, followed by Caucasians and least common in Asia.  Prostate cancer ranked among the leading cause of morbidity and mortality worldwide. Studies have shown that it is the second most common cause of cancer mortality in Caucasians.  Although Caucasians and blacks have a high mortality rate, reports indicates that Trinidad and Tobago has the highest age-adjusted prostate cancer mortality rate of 32.9 per 100,000 population, while Japan have the lowest mortality rates of 4 per 100,000 population.  Prostate cancer prognostic index can be assessed by Gleason's scoring system. It is a method of predicting the degree of severity of the disease.  Prostate cancer with high Gleason's score is often associated with aggressive behavioral pattern. 
This report is aimed at identifying the prevalence, histopathological patterns, and prognostic index of prostate cancer from 2001 to 2010 in a private practice setting of an African population.
| Materials and Methods|| |
This study was conducted on 908 prostatectomy specimen from Ashamas foundation clinic, in Benin-City, South-South, Nigeria between 1 st of January 2001 and 31 st December 2010. This center is the only private center in Benin-City metropolis and Edo State offering histopathology services. Therefore, prostatic specimens were sent from surgeons and urologists having private and public group practice in Benin-City metropolis and different parts of Edo State. Clinical information regarding age, clinical history, type of biopsy fragments removed on biopsy, and clinical diagnosis was retrieved and documented. Biopsies were received in 10% formalin. Specimen were grossed, the weight and measurement of all the samples were recorded. The tissues were processed with an automated tissue processor, paraffin embedded, and sectioned at 3-5 microns. Slides were made and stained with hematoxylin and eosin preparation. All specimens were sub-classified into benign and malignant lesions. The type of malignant tumors was classified according to the World Health Organization (W.H.O) histological classification and the Gleason scoring system. 
Data obtained were entered in Microsoft excel, coded, transferred, and expressed as percentage for categorical variables and the mean ± standard deviation (SD) for continuous variables using the statistical packaging for social sciences (SPSS) version 17 statistical package (SPSS) incorporated, Chicago, Illinois, USA.
| Results|| |
During this 10-year study, a total of 908 prostatic tumors and 226 urological malignancies were diagnosed histologically in a private practice setting. Among this, 214 were prostatic malignancies. Prostatic malignancy, therefore, constitutes 23.6% and 94.7% of all prostatic tumor and urological tumor, respectively. [Table 1] shows the age distribution of prostatic malignancy. The peak age range was 70-79 years constituting 83 cases (38.8%) of all age group. The mean age for prostate cancer was 68 ± 4.6 years.
[Table 2] shows the different histological types of prostatic malignancy. Prostatic adenocarcinoma accounted for 201 cases constituting 93.9% of prostatic malignancies. Six cases had incidental carcinomas. This accounted for 2.8% of prostatic malignancy. Other rare findings were cases of high-grade prostatic intraepithelial neoplasia (HG-PIN) constituting two cases (0.9%). Other extremely rare cases encountered in this study include transitional cell carcinomas and metastatic carcinoma accounting for two cases (0.9%) and one case (0.5%) were, respectively, seen. Notably, two cases of prostatic sarcomas as seen in [Table 2] were encountered.
Gleason scoring system
In [Table 3], all biopsies were graded according to the Gleason's scoring criteria. A total of 53 (30.4%) of all 174 cases scored were Gleason's score 2-4 representing well-differentiated prostatic adenocarcinoma), 104 cases accounting for 59.8% were moderately differentiated with Gleason's score 5-7, and 17 cases constituting 9.8% were Gleason's score 8-10 (poorly differentiated). The peak Gleason's score incidence was Gleason's score 6 accounting for 55 cases (31.6%).
|Table 3: Gleason's scoring of prostate adenocarcinoma of 174 patients in relation to age |
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| Discussion|| |
Our study has shown that prostatic malignancies accounted for 94.7% of all urologic malignancies. This findings is consistent with previous reports from other researchers in Africa and globally where it accounted for first majority of all urological tumors. , Currently, global statistics series have documented that prostate cancer is the most frequently diagnosed cancer in men and also the most common genitourinary cancer in men. ,,,
This study has, however, shown that prostate cancer accounted for 23.6% of all prostatic tumor histologically diagnosed. Of, this, prostatic adenocarcinoma is the first majority constituting 96.7% in this series. This finding is quite similar to reports documented by Talukder et al.,  where prostate cancer accounted for 22.6% of all prostatic tumors and prostatic adenocarcinoma constituted 90.5% of all prostatic cancer.  This report is supported by both Africa and global researchers. ,,,
Most cases of prostate cancer encountered in this study have peak incidence between 60 and 79 years accounting for 73.4%. No case was reported before the age of 40 years and only few cases were reported after 80 years of age. This again is in tandem with African and Caucasian series where age is the major risk factor to the disease. , The disease was reported to be extremely rare before the 4 th decade of life. This steep rise in its incidence in our environment is similar to previous reports by Aligbe et al.  Similar reports from other Africa studies have corroborated this findings. ,,, However, this is slightly at variance with reports from African-American and European series where the incidence rise steadily as the age increases. , The reason for this is partly adducible to better life expectancy in developed countries. Globally, there is general increase in prostate cancer incidence over the years. This is attributed to the fact that there is more global awareness of the scourge of the disease; this invariably had led to improved health care seeking behavior of most male patients.
Our study of prostatic cancer was graded using the Gleason's scoring system. We found out that moderately differentiated prostatic adenocarcinoma with (Gleason's score 5-7) was the most common accounting for 59.8% in the series. Meanwhile, well-differentiated prostatic adenocarcinoma corresponding to (Gleason's score 2-4), accounted for 30.4% and the remaining 9.8% was poorly differentiated prostatic adenocarcinoma having (Gleason' score 8-10). This report is at variance with separate reports by Catalona et al., and George and Sosamma , which indicated that poorly differentiated prostatic adenocarcinoma was the most common accounting for 60% and 68%, respectively. However, our report is also at variance with reports from a teaching hospital in Benin, by Forae et al.,  where well-differentiated adenocarcinoma constituted the common majority (45%). This clearly indicates that our patients in this private practice setting in Benin have slightly more aggressive course than reports documented in the teaching hospital setting. However, our report is less aggressive than reports by Catalona et al.  In addition, numerous studies of tumor grade reported that African-Americans have higher tumor grade and volumes than Caucasian counterparts with a similar stage of the tumor. , All these observations suggest that biological differences in tumorigenesis may be a factor in the course of disease among races.  Further reason for this variation may partly be attributable to geo-ethnical variation, environmental factors, dietary, and genetic factors.
Only 0.9% of HG-PIN was encountered during this study. This is different from reports by Orozco et al.,  where prevalence of HG-PIN was 4.1%. Reports have it that most African-Americans in their 3 rd decades of life and beyond who died from other diseases had an increased incidence of HG-PIN as compared with their Caucasian counterparts. , Generally, the reason that can be adduced to this low prevalence of HG-PIN in this study is partly due to the fact that most patients with HG-PIN are asymptomatic and their serum prostate-specific antigen (PSA) is not readily elevated and as such may not seek medical attention and intervention. However, it is advised that direct rectal examination and PSA be adequately combined as a screening modalities to detect early premalignant lesions and regular health education is necessary to change the attitude of men toward better health care seeking behaviors. 
In this study, other types of prostate cancer were rare. Only 0.9% and 0.5% of all prostate cancer accounted for transitional cell carcinoma and metastatic carcinoma, respectively. Meanwhile, fibrosarcoma and carcinosarcoma were also extremely rare constituting about 0.5% each. The rarity of these other histological types of prostate cancer as seen in this study is consistent with global and local reports documented by other researchers.
Incidental carcinoma in this study was also rare constituting 2.8% in the series. This is slightly similar to other work by Akang et al.,  where incidental carcinoma accounted for 9.1%. However, most researchers globally believed that most cases of incidental carcinomas are under reported. The reason for this is partly due to the fact most developing countries do not have elaborate cancer register for adequate documentation of cases. Moreso, in places where biopsies were taken, adequate biopsies with serial sectioning techniques were not fully employed. Most cases discovered go unreported even when discovered at autopsy. It is important to state here that our private practice findings may not be the true reflection of incidental carcinoma cases in our environment due to the fact that this study is a retrospective study. Given that hospital-based incidence records do not reflect the exact incidence incidental prostate cancer in Nigeria. , The need for population-based study is recommended to uncover latent and incidental carcinoma cases, especially in men in their 4 th decade and beyond. 
| Conclusion|| |
This study revealed that prostate cancer is the most common malignant tumor of the urogenital system in males with majority as moderately differentiated adenocarcinoma (Gleason score 4-7). Yet again, vast majority of these histologically confirmed cases are seen in middle-aged and elderly patients. Currently, it constitutes a source of morbidity and mortality in men. We advocate adequate screening and a population-based study to uncover precursor lesion, latent, and incidental carcinoma cases in Nigeria.
| Acknowledgment|| |
Both authors wish to thank staffs of Ashama foundation clinic for their technical assistance and retrieval of archival materials. Their generosity made this research possible. We also wish to thank Dr. P. Akumabor, a consultant urologist and the staff of Zuma medical centre Benin-City as well as other private clinics that provided the samples.
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[Table 1], [Table 2], [Table 3]