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  Table of Contents  
ORIGINAL ARTICLE
Year : 2013  |  Volume : 50  |  Issue : 3  |  Page : 159-163
 

Prostate cancer disease characteristics for foreign-born South Asian men living in the United States


1 Department of Urology, Columbia University College of Physicians and Surgeons, NY, USA
2 Vattikuti Urology Institute, Henry Ford Hospital, Detroit, MI, USA

Date of Web Publication23-Sep-2013

Correspondence Address:
T Patel
Department of Urology, Columbia University College of Physicians and Surgeons, NY
USA
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0019-509X.118715

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 » Abstract 

Introduction: We report the largest known cohort of South Asian (SA) men treated by radical prostatectomy living in the United States. Our objective was to characterize this sub-population and compare them to our wider cohort of prostate cancer patients treated with radical prostatectomy in the United States. Materials and Methods: All patients who underwent radical prostatectomy at two high-volume United States academic institutions at separate geographic locations between 1990 and 2011 were identified. Demographic data, pre-operative Prostate Specific Antigen (PSA), biopsy Gleason score, pathology Gleason score, pathology Stage, margin status, and node status were collected. In addition to SA men, African American (AA) men were identified and used for comparative analysis as a high-risk cohort. Results: A total of 69 SA men were identified in Cohort 1 and 24 men were identified in Cohort 2. When comparing SA men against the entire cohort, no significant difference was found for age, year of surgery, biopsy Gleason score, or path Gleason score for either cohort. However, significant differences were found in pre-operative PSA (P = 0.01), pathologic stage (P<0.01), and positive node status (P = 0.04) for SA men in Cohort 1. Whereas in Cohort 2, SA men had a significantly higher proportion of positive surgical margins (P = 0.04). In all significant comparisons, characteristics were worse in SA men and similar to that of AA men. Conclusions: SA men have worse pathologic disease profiles when compared to the general population of men undergoing radical prostatectomy. SA men living in the United States have pathologic disease profiles that are comparable to AA men.


Keywords: Prostate cancer pathology, radical prostatectomy, South Asian


How to cite this article:
Patel T, Wambi C C, Berg W, Inusa M D, Menon M, Badani K. Prostate cancer disease characteristics for foreign-born South Asian men living in the United States. Indian J Cancer 2013;50:159-63

How to cite this URL:
Patel T, Wambi C C, Berg W, Inusa M D, Menon M, Badani K. Prostate cancer disease characteristics for foreign-born South Asian men living in the United States. Indian J Cancer [serial online] 2013 [cited 2019 Aug 20];50:159-63. Available from: http://www.indianjcancer.com/text.asp?2013/50/3/159/118715



 » Introduction Top


Prostate cancer ranks as the second most frequently diagnosed cancer in men worldwide, accounting for approximately 240,000 deaths annually. [1] Despite its global reach, striking variances in the pattern of incidence and mortality by region and race have been observed. In the United States, African American (AA) men are at the highest risk developing prostate cancer with an annual incidence 178/100,000; however, with respect to Asian Americans this rate drops to 88.3/100,000. [2],[3] Within this subgroup, the South Asian (SA) population (Indian, Pakistani, Nepalese, Bangladeshi, and Sri Lankan) represents the 3 rd largest Asian American population in the United States. Prostate cancer incidences in this population have been reported to range from 3.9-9.1/100,000. [1],[3],[4] Differences in diet and availability of screening have all been implicated in the lower incidence of prostate cancer in this population. However, there has been outcome analysis to show that despite this lower incidence of prostate cancer, SA men have worse survival when compared to Caucasians. [5] In a recent study, Tewari et al. showed that Indian Americans were more likely to have higher stage and Gleason score when compared with whites; however, found no difference with respect to biochemical recurrence. [6] Despite this study, the discrepancy between incidence and pathologic/clinical outcomes with prostate cancer in the SA population living in the United States has received little attention, and as such, there exists a paucity of literature on this topic. We report the largest cohort of foreign-born SA men treated by radical prostatectomy in the United States. The purpose of this study was to further characterize tumor characteristics within this population and to compare it to a larger cohort of AA males in the same geographical region, as well as the entire cohort of men treated.


 » Materials and Methods Top


The Institutional Review Board approved Columbia University Urologic Oncology Database and Vattikuti Urology Institute at Henry Ford Hospital experience was retrospectively reviewed for patients with localized prostate cancer treated with radical prostatectomy from 1990-2011. Men who self-identified as SA were identified. In addition, we used a previously validated surname analysis to identify additional cases of SA men who did not self-report. [7] Out of a total of 10,053 of patients who underwent radical prostatectomy at these two institutions, 93 (0.9%) were identified to be SA and 1179 (11.7%) were AA. All SA patients were born outside the United States.

Clinical and pathological data including age, PSA level at diagnosis, biopsy Gleason score, clinical stage, pathological Gleason score, pathological stage, number of LNs examined, and surgical margin status were all recorded. Prostate specimens were staged using the 2010 American Joint Committee on Cancer TNM staging system. After prostatectomy, patients were evaluated with serial PSA tests, Digital Rectal Exams (DREs), and imaging studies as deemed necessary.

A comparative analysis between SA men and our high-risk cohort of AA men was done for each individual institution. Categorical variables were assessed using χ² test, with continuous parametric data analyzed through Student's t tests. A P value of less than 0.05 was considered to be significant. All statistical analysis was done using SPSS 17.0 (SPSS Inc, Chicago, IL).


 » Results Top


Vattikuti urology institute (VUI) at Henry Ford hospital experience

Between 2001 and 2011, 5115 patients underwent radical prostatectomy (RP) for clinically localized prostate cancer at the VUI by one of four surgeons. Nineteen patients with unknown stage were excluded from the analysis. Among the remaining 5096 patients, 69 (1.4%) were identified of SA origin and 746 (14.6%) were identified as AA origin. [Table 1] summarizes the preoperative and descriptive characteristics of the cohort. The mean age of SA men in this cohort was 61.4 compared with 59.0 for AA. Mean preoperative PSA was 8.8 ng/mL in SA men and 7.4 ng/mL in AA men. SA men had a significantly higher preoperative PSA when compared with the entire cohort (8.8 ng/mL vs. 6.4 ng/mL; P = 0.01). Seventy-four percent of SA men had ≥ 7 Gleason score on preoperative biopsy compared with 79% of AA men.
Table 1: Descriptive statistics VUI experience


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[Table 2] compares pathological outcomes between SA and AA. Pathologic specimen Gleason score was similar between both groups, but SA men had significantly higher Gleason scores than the entire cohort. Gleason 6 was found in 26.1% of SA men and 20.6% of AA men. High-grade disease (Gleason ≥ 8) was present in 15.9% of SA and 12.8% of AA men. A significantly greater percentage of SA men compared with AA men had extraprostatic extension (EPE) and seminal vesicle invasion (SVI) (49.3% vs. 38.0%; P = 0.03). When comparing positive margin rate, SA men had a higher incidence compared with AA men but was not found to be statistically significant (34.8% vs. 28.6%; P = 0.3). AA men did have a statistically higher rate of positive lymph nodes compared with SA men (5.4% vs. 1.5%; P = 0.01).
Table 2: Pathologic statistics of VUI experience

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Columbia University Medical Center experience

Between 1990 and 2011, 5026 patient underwent radical prostatectomy for clinically localized prostate cancer at Columbia University Medical Center. Twenty-four men (0.4%) were identified of SA origin and 703 (14%) were identified to be AA. [Table 3] summarizes the preoperative and descriptive characteristics of the cohort. The mean age of SA men in this cohort was 61.5 compared with 59.5 for AA. Mean preoperative PSA was 8.2 ng/mL in SA men and 8.0 ng/mL in AA men. There was no difference in preoperative PSA in SA men when compared with the entire cohort. Seventy percent of SA men had ≥ 7 Gleason score on preoperative biopsy, compared with 79% of AA men.
Table 3: Descriptive statistics of Columbia University experience

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[Table 4] compares pathological outcomes between SA and AA. Pathologic specimen Gleason score was similar between both groups. Gleason 6 found in 30.4% of SA men and 21.3% of AA men. High-grade disease (≥ 8) was present in 13.1% of SA and 16.3% of AA men. A greater percentage of SA men compared with AA men had EPE and SVI (39.1% vs. 32.4%, P = 0.25). When comparing positive margin rate, SA men had a lower incidence compared with AA men but was not found to be statistically significant (26.1% vs. 30.9%; P = 0.6). No SA men had evidence of positive lymph nodes, compared with 15 AA men.
Table 4: Pathologic statistics of Columbia University experience

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 » Discussion Top


This present analysis was intended to identify pathological outcomes in SA men who reside in the United States that were treated with radical prostatectomy for localized prostate cancer at two different institutions and to compare these results with a group of AA men. Currently, our study represents the largest cohort of SA men treated in the United States. Our findings, interestingly, showed that SA men have comparable, if not worse, pathological variables than AA men. In SA men treated at the VUI, we found that SA men had significantly higher pathologic stages of disease when compared with AA men. A higher rate of positive margins was also found in SA men, although not statistically significant. The cohort of SA men treated at Columbia University was found to have comparable grade and stage of disease after radical prostatectomy with that of AA men. In both cohorts, preoperative PSA was found to be slightly higher on average in SA men than AA men; however, this was not statistically significant. Although multiple studies have shown that SA men have a lower risk of being diagnosed with prostate cancer, [4],[8],[9] our study suggests that when prostate cancer is found in SA men, it shows characteristics of disease similar to that of in AA men who are at a high risk of prostate cancer mortality. [10],[11],[12] If SA men exhibit similar pathologic characteristics to AA men after radical prostatectomy, then it would be prudent for them to follow similar early screening guidelines and be treated as a high-risk demographic population.

In a report of pathological outcomes of Asian Indian men, Tewari et al. found that Asian Indian men who were treated in the United States had higher stage and grade of disease when compared with Caucasians. [6] Despite these findings, no difference in biochemical recurrence was found between the two groups. although this study did not compare AA men with their Asian Indian cohort, we did show that SA men had worse pathologic features compared with the general cohort, which included a majority of Caucasian men. Goggins et al. using SEER data found that Asian Indians/Pakistanis, although having lower rate of prostate cancer when compared with Caucasians, were more likely to have higher grade cancer than Caucasians. [8] This analysis failed to show any difference in all-cause mortality after adjusting for disease traits. Similarly, Zeigler-Johnson et al. showed that Asian Indians had a significantly higher risk of higher Gleason grade and risk of metastatic disease when compared with European Americans. [9] With respect to disease-specific mortality, a study from the California Cancer Registry found the 10-year risk of death from prostate cancer to be 40% higher in SA men than in Caucasians. [5] Our results are consistent with these other published reports regarding pathologic outcomes; however, these disparate results in reference to survival may be attributed to the heterogeneity of the South Asian population, which only highlights the importance of further study and characterization in this population.

The inverse relationship between incidence and virulence of prostate cancer in SA men has been subject to several hypotheses. although natural biologic variance cannot be excluded, it is possible that SA men are more likely to have early treatable disease remaining undetected until a later stage of disease, thus resulting in the final pathology results presented in this paper. Tewari et al. has surmised that this could be a result of the lack of information on PSA kinetics in SA men and the notion that since SA men are at lower risk of disease they are less subject to screening, which leads to delayed diagnosis. [6] An analysis of cancer registries in five Indian cities has shown that prostate cancer incidence has increased over the last 20 years with annual percentage changes ranging from 0.89 to 4.95. [13] In part, this reflects an increase in the use of PSA screening and prostate cancer awareness, which may ultimately lead to earlier diagnosis. Our study reflects data of SA men living in the United States where awareness of prostate cancer screening is if not ubiquitous, a hot topic of discussion. Although we agree with Tewari et al. regarding delayed diagnosis in SA men as a possible explanation of their aggressive disease of men living in Asia, we think of this effect to be less pronounced in SA men living in the United States due to high publicity prostate cancer screening. Our results suggest that the biology of prostate cancer in SA men may drive the differences in presentation we see in this population of men.

Our study does have some limitations. Despite reporting, to our knowledge, the largest series of SA men undergoing radical prostatectomy, our cohort remains small. The small number of SA men undergoing radical prostatectomy at Columbia University over a 20-year period in an ethnically diverse location highlights the difficulty at which to gather information regarding SA men in this country. We also acknowledge the possibility of racial misclassification, although we did use a validated surname analysis tool to help us identify men of SA origin. Finally, we lack disease-specific mortality data, which would help elucidate whether these worse pathologic features resulted in worse disease-specific outcomes.


 » Conclusions Top


Our study finds that SA men living in the United States have pathologic disease profiles that are comparable with AA men. Further data is needed to understand the biologic, epidemiologic, and social influences that affect the natural history of prostate cancer in SA men.

 
 » References Top

1.Ferlay J, Shin HR, Bray F,Forman D, Mathers C, Parkin DM. Estimates of worldwide burden of cancer in 2008: GLOBOCAN 2008. Int J Cancer 2010;127:2893-917.  Back to cited text no. 1
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2.Jemal A, Siegal R, Xu J, Ward E. Cancer statistics, 2010. CA Cancer J Clin 2010;60:277-300.  Back to cited text no. 2
    
3.Jemal A, Bray F, Center MM, Ferlay J, Ward E, Forman D. Global cancer statistics. CA Cancer J Clin 2011;61:69-90.  Back to cited text no. 3
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4.Hebert JR, Ghumare SS, Gupta PC. Stage at diagnosis and relative differences in breast and prostate cancer incidence in India: Comparison with the United States. Asian Pac J Cancer Prev 2006;7:547-55.  Back to cited text no. 4
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5.Robbins AS, Koppie TM, Gomez SL, Parikh-Patel A, Mills PK. Differences in prognostic factors and survival among white and Asian men with prostate cancer, California, 1995-2004. Cancer 2007;110:1255-63.  Back to cited text no. 5
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6.Tewari AK, Srivastava A, Sooriakumaran P, Grover S, Desir S, Dev H, et al. Pathological outcomes and strategies to achieve optimal cancer control during robotic radical prostatectomy in Asian-Indian men. Indian J Urol 2011;27:326-30.  Back to cited text no. 6
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7.Shah BR, Chiu M, Amin S, Ramani M, Sadry S, Tu JV. Surname lists to identify South Asian and Chinese ethnicity from secondary data in Ontario, Canada: A validation study. BMC Med Res Methodol 2010;10:42.  Back to cited text no. 7
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8.Goggins WB, Wong G. Cancer among Asian Indians/Pakistanis living in the United States: low incidence and generally above average survival. Cancer Causes Control 2009;20:635-43.  Back to cited text no. 8
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9.Zeigler-Johnson CM, Rennert H, Mittal RD, Jalloh M, Sachdeva R, Malkowicz SB, et al. Evaluation of prostate cancer characteristics in four populations worldwide. Can J Urol 2008;15:4056-64.  Back to cited text no. 9
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10.Du XL, Fang S, Coker AL, Sanderson M, Aragaki C, Cormier JN, et al. Racial disparity and socioeconomic status in association with survival in older men with local/regional stage prostate carcinoma: Findings from a large community-based cohort. Cancer 2006;106:1276-85.  Back to cited text no. 10
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11.Evans S, Metcalfe C, Ibrahim F, Persad R, Ben-Shlomo Y. Investigating Black-White differences in prostate cancer prognosis: A systematic review and meta-analysis. Int J Cancer 2008;123:430-5.  Back to cited text no. 11
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12.Albain KS, Unger JM, Crowley JJ, Coltman CA, Hershman DL. Racial disparities in cancer survival among randomized clinical trials patients of the Southwest Oncology Group. J Natl Cancer Inst 2009;101:984-92.  Back to cited text no. 12
    
13.Yeole BB. Trends in the prostate cancer incidence in India. Asian Pac J Cancer Prev 2008;9:141-4.  Back to cited text no. 13
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  [Table 1], [Table 2], [Table 3], [Table 4]



 

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