The prevalence of high-grade prostatic intraepithelial neoplasia in surgical resection specimens
An Indian experience
To the authors' knowledge there is a paucity of literature regarding the prevalence of high-grade prostatic intraepithelial neoplasia (HGPIN) in the Indian subcontinent. The objective of the current study was to document the prevalence of HGPIN in a low-risk Indian population.
A total of 110 prostate specimens (61 taken from the test group and 49 taken from the control group) were studied to document the prevalence of HGPIN in a low-risk Indian population.
None of the benign prostate samples were found to harbor HGPIN, whereas 85.24% of the samples from malignant prostates did so.
A strong correlation between HGPIN and invasive carcinoma was observed, a finding that reinforces the view that HGPIN is a strong indicator of concurrent invasive prostate carcinoma. Cancer 2002;94:2350–2. © 2002 American Cancer Society.
The prevalence of and the mortality due to prostate carcinoma have been reported to vary among different ethnic groups and populations.1 The prevalence of prostatic intraepithelial neoplasia (PIN) in malignant prostate samples has been reported to vary from 60–100%. High-grade PIN (HGPIN) reportedly is detected in 33–100% of malignant prostates compared with benign prostates (range, 4–18%).2 To our knowledge, the majority of published reports concerning PIN have been from the Western world.
The incidence of prostate carcinoma in India is very low compared with that in the Western hemisphere.3 The current study was undertaken to document the prevalence of HGPIN detected in normal, benign, and malignant prostates in patients examined at the study institution.
MATERIALS AND METHODS
A total of 110 cases were studied to assess the prevalence of HGPIN. The case materials were reviewed by two pathologists. The criteria used for the diagnosis of HGPIN were those described in the literature.2
The test group (n = 61) was comprised of radical prostatectomy samples (n = 39), prostate biopsy samples (n = 2), and transurethral prostatectomy (TURP) samples (n = 17) performed in patients with prostate carcinoma and cystoprostatectomy samples (n = 3) from patients with carcinoma of the urinary bladder that demonstrated incidental prostate carcinoma.
The control group (n = 49) was comprised of radical cystoprostatectomy samples (n = 41) from patients with urinary bladder carcinoma and TURP samples (n =7) and a prostatectomy sample (n = 1) from patients with benign prostatic hyperplasia (BPH).
When examining radical prostatectomy and cystoprostatectomy specimens, prostates were embedded completely, serially sectioned, and processed entirely and routinely before they were analyzed.
The average ages of the patients in the control group were 54.4 years (bladder carcinoma cases) and 62.1 years (BPH cases), whereas the average ages of the patients in the test group were 56.3 years (prostate carcinoma cases) and 63.5 years (incidental prostate carcinoma cases).
HGPIN was noted in 85.24% of the test cases and always was closely associated with invasive carcinoma of the prostate. None of the control cases were found to harbor this abnormality.
Of the 61 test cases, 52 demonstrated the presence of HGPIN and 9 did not. The prevalence of HGPIN among the different samples was as follows: 36 of 39 radical prostatectomy cases, 2 prostatic biopsy cases, 11 of 17 TURP cases, and all 3 cystoprostatectomy cases.
The absence of HGPIN in the remainder of the test cases (14.7%) was attributed to the limited material available for study (6 TURP cases) and prior hormonal treatment (2 cases).
High-grade prostate carcinoma in the absence of HGPIN was noted in four of six TURP specimens. Invasive prostate carcinoma in these cases was of high grade with a Gleason score of 8 (one case), 9 (one case), and 7 (two cases).
The incidence of prostate carcinoma is increasing rapidly in low-risk populations. Increasing incidence rates in Asian countries most likely are related to the “Westernization” of these low-risk populations. In a recent study by Hsing et al.,4 relatively large increases in the incidence of prostate carcinoma were observed in Asian countries during a 20-year period. However, although to our knowledge no significantly large increase in prostate carcinoma has been documented in the Indian population, an increasing trend has been noted.3, 4
It is logical to conclude that the prevalence of HGPIN should parallel that of invasive prostate carcinoma. Considering the relatively low incidence of invasive prostate carcinoma in the Indian population, it is inconceivable that the incidence of HGPIN in the Indian population would be as high as that reported in the Western population.
In the current study, a majority of prostate carcinoma specimens (85.24%) were found to harbor HGPIN. Conversely, none of the benign prostate samples were found to have HGPIN. On the contrary, in a study from Sri Lanka, 4.39% of samples were found to contain HGPIN in the absence of adenocarcinoma.5
Four of six TURP specimens with high-grade invasive carcinoma were not found to contain HGPIN. This finding can be explained by the observation that high-grade tumors tend to override the areas of HGPIN. Sakr et al.6 have reported a reciprocal relation between the grade, volume, and extent of HGPIN.
It also was worth noting in the current study that none of the specimen sections with HGPIN were without invasive carcinoma, a finding that reflects the coexistence, simultaneous occurrence, and physical proximity of the two entities. This further strengthens the belief that the HGPIN observed in the presence of invasive carcinoma in all probability is a form of invasive carcinoma that remains confined to an anatomic unit rather than existing as a truly “in situ” process. This view is amply supported by and extrapolated from similar observations made pertaining to intraductal carcinoma of the breast.7, 8
The incidence of prostate carcinoma continues to increase in the Indian subcontinent. Therefore, a diagnosis of HGPIN may be encountered more often. We concur with other authors9 and reemphasize the belief that a diagnosis of HGPIN on a prostate biopsy should warrant additional results or additional biopsies for the detection of coexistent invasive adenocarcinoma of the prostate.