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ORIGINAL ARTICLE
Year : 2022  |  Volume : 18  |  Issue : 6  |  Page : 1646-1650

Correlation of digital rectal examination and serum prostate-specific antigen levels for detection of prostate cancer: Retrospective analysis results from a tertiary care urology center


1 Department of Urology, Institute of Post Graduate Medical Education and Research, Kolkata, West Bengal, India
2 All India Institute of Medical Sciences Jodhpur, Rajasthan, India

Date of Submission20-Dec-2020
Date of Acceptance15-Mar-2022
Date of Web Publication16-Nov-2022

Correspondence Address:
Dilip Kumar Pal
Department of Urology, Institute of Post Graduate Medical Education and Research, Kolkata - 700 020, West Bengal
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jcrt.JCRT_1818_20

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 > Abstract 


Objective: The objective of our study was to evaluate the detection rate of prostate cancer by digital rectal examination (DRE) and serum prostate-specific antigen (PSA) levels followed by standard 12-core transrectal ultrasound (TRUS)-guided prostate biopsy.
Materials and Methods: After screening of patients presenting with lower urinary tract symptoms (LUTS) using DRE and serum PSA level, we enrolled patients for TRUS-guided 12-core prostate biopsy. Indications included PSA level ≥4 ng/ml and/or suspicious DRE findings. A retrospective analysis was done to find out the correlation between suspicious rectal examination and various serum PSA levels in detection of cancer prostate.
Results: A total of 847 patients were screened for cancer prostate during our study period (May 2012–February 2020). Among them, 823 patients who underwent prostate biopsy were analyzed. Prostate cancer was detected in 330 cases (40.09%). Mean age of patient (years) with and without prostate cancer was 66.25 ± 9.45 and 64.3 ± 8.96 years, respectively. Median value of serum PSA in patients positive for cancer was 33 ± 260 ng/ml compared to patients without cancer, who had a median value of 9 ± 64 ng/ml (P-value of <0.0001). The detection rate of cancer based on suspicious DRE findings irrespective of PSA was 52.18% (251/481), compared to 45.46% (311/684) using a PSA cut-off of ≥4.0 ng/ml alone. Among 330 patients with positive biopsy, 19 (5.75%) had a PSA level <4 ng/ml and they were identified based on suspicious DRE alone.
Conclusion: Suspicious DRE was significantly associated with detection of prostate cancer across all PSA levels. Patients with PSA <4 can harbor prostate malignancy and such cases can be detected by use of DRE in screening of all patients with LUTS.

Keywords: Digital Rectal Examination, prostate cancer, prostate-specific antigen, TRUS biopsy


How to cite this article:
Sarkar D, Jain P, Gupta P, Pal DK. Correlation of digital rectal examination and serum prostate-specific antigen levels for detection of prostate cancer: Retrospective analysis results from a tertiary care urology center. J Can Res Ther 2022;18:1646-50

How to cite this URL:
Sarkar D, Jain P, Gupta P, Pal DK. Correlation of digital rectal examination and serum prostate-specific antigen levels for detection of prostate cancer: Retrospective analysis results from a tertiary care urology center. J Can Res Ther [serial online] 2022 [cited 2022 Dec 2];18:1646-50. Available from: https://www.cancerjournal.net/text.asp?2022/18/6/1646/361203




 > Introduction Top


The incidence of prostate cancer in developed countries is increasing; however, in the developing world, it still remains underdiagnosed with late presentation.[1] Prostate cancer is evolving in terms of diagnosis and management and is becoming an important health issue with every passing year. With widespread propagation of prostate-specific antigen (PSA) in detection of prostate cancer, digital rectal examination (DRE), which was once a fundamental component of prostate cancer screening regimens, has become oblivious.[2] PSA is being a more useful tool for diagnosis of prostate carcinoma so much so that it does pick carcinoma from those cases which are missed by DRE.[3] Having said that, at present, both these screening measures are under shadows; the role of DRE in various studies is conflicting and that of threshold PSA levels as an indication for prostate biopsy is unclear. Since most variants of abnormal DRE alone do not effectively predict the risk of carcinoma, in combination with raised PSA they can predict the same.[4] Results of European Randomized Study of Screening of Prostate Cancer (ERSPC) revealed that abnormal DRE was associated with prostate cancer in the setting of elevated PSA; however, the role of DRE in the setting of normal PSA remained understudied.[5],[6] Various guidelines have discordant opinions regarding use of DRE. The American Urological Association (AUA) found no evidence in support of DRE, whereas the National Cancer Care Network (NCCN) advocated DRE screening only in those men with elevated PSA.[7],[8]

Transrectal ultrasound (TRUS)-guided prostate biopsy is the vital element in diagnosis of prostate cancer. Revolution in diagnosis of prostate cancer happened in early 1990s, with influx of three important developments: firstly, the adoption of a systematic rather than random biopsy scheme, as described by Hodge et al.,[9] secondly, the use of a biopsy gun as opposed to hand-operated Tru-cut needles, and thirdly, the advent of the TRUS probe, enabling the clinician to visually guide the biopsy needle.[10] The consensus today for initial biopsies is to use a minimum of 10–12 laterally directed biopsies from the peripheral zones with the use of TRUS.[11],[12] In our study, we analyzed the detection rate of prostate cancer on contemporary 12-core TRUS biopsy in men with either suspicious DRE and/or PSA ≥4.0 ng/ml.


 > Materials and Methods Top


After screening of the study population by serum PSA and DRE, we included all patients who underwent first TRUS-guided prostate biopsy at our institution during the study period from May 2012 to February 2020. Clinical parameters including patient demographic profile, serum PSA value (in sterile urine), and DRE findings were recorded in well-prepared chart. DRE was performed by urological surgeons who were experienced with examination of prostate cancer patients. DRE was considered positive/suspicious in the presence of indurations, nodularity, significant asymmetry, or loss of anatomic landmarks, as determined by the examiner.[13] The inclusion criterion for taking biopsy was suspicious DRE and/or serum PSA value ≥4 ng/ml or both. Measurement of serum PSA level was repeated if the urine culture was positive. TRUS was performed using a Samsung diagnostic ultrasound machine (model no. SONOACER7) with a 7.5-MHz transrectal end firing probe. The findings on TRUS were documented for both the right and left lobes with a special mention to the presence of hypoechoic areas, calcifications in the periphery and center of the glands, as well as the presence of capsular distortion.

The number of biopsies taken was documented. A routine 12-core (two cores from apex, mid-zone, and base of prostate on the periphery of both lobes) biopsy was the standard protocol and we sent all cores separately with proper labeling. Whenever required, we biopsied suspicious areas in addition to standard 12 core. The core specimens were examined by pathologists at the same institution. Complete datasheets and pathology reports were collected for all patients. Histopathology report was available for all the patients. Gleason score was determined according to the standard criteria among all tissue samples for each subject.

Histological diagnoses were classified for the purposes of analysis into benign if reported as normal prostate or benign prostatic hyperplasia or inflammation. It was reported as suspicious for malignancy if reported as atypical, atypical small acinar proliferation (ASAP), or high-grade prostatic intraepithelial neoplasia (HGPIN). We excluded those patients from analysis who were reported as ASAP, HGPIN, or who required repeat biopsy. Subjects who had previous prostate biopsy, prostate surgery, or known diagnosis of prostate cancer were also excluded from the study.

Data were compiled using MicroSoft Excel®, and statistical analysis was performed by a biostatistician on Stata® software using the Mann–Whitney U test for continuous variables and the Pearson's Chi-squared test for categorical variables. A two-tailed P value of <0.05 was accepted as significant with a power of 80%.


 > Results Top


Out of 847 patients who underwent prostate biopsy, 823 patients fulfilled the inclusion criteria. Among them, 330 (40.09%) patients were found to be positive for malignancy. Mean age of patients positive and negative for cancer was 66.25 ± 9.45 and 64.3 ± 8.96 years, respectively. Median serum PSA levels were 33 ± 260 and 9.02 ± 64 ng/ml in patients who were positive and negative for malignancy, respectively. Serum PSA level of more than 4 was found in 684 (83.11%) cases, whereas suspicious DRE was present in 481 (58.44%) cases. [Table 1] shows patient characteristics with reference to various parameters. Also, 30.49% (251) were found to be malignant based on suspicious DRE finding, irrespective of the PSA value. Similarly, patients with a PSA value ≥4 had 37.78% (311) malignancy, irrespective of the DRE findings.
Table 1: Characteristics of the study population

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Absolute PSA values were recorded and categorized for the purposes of analyses into five groups: 0–2.5, 2.51–4.0, 4.01–10.0, 10.01–20.0, and >20.01 ng/ml. Their corresponding overall prostate cancer detection rates, regardless of the DRE findings, were 14/94 (14.89%), 5/45 (11.11%), 37/188 (19.68%), 51/184 (27.71%), and 223/312 (71.47%), respectively. The corresponding overall cancer detection rates of suspicious DRE findings were 14/94 (14.89%), 5/45 (11.11%), 26/62 (41.93%), 37/68 (54.41%), and 169/212 (79.71%), respectively [Table 2]. Men with prostate cancer were more likely to have suspicious DRE findings in the 4.00–9.99, 10.00–20.00, and >20.00 ng/ml serum PSA categories (P-value < 0.0001 in all categories), respectively. The detection rate of cancer based on abnormal DRE alone was 30.49% (251/823); however, when a cut-off of PSA ≥4 ng/ml was used, the detection rate of cancer in these patients increased to 45.46% (311/823) [Table 3].
Table 2: Serum PSA level, DRE findings, and prostate cancer detection rate

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Table 3: Characteristics of DRE at various serum PSA levels for overall prostate cancer detection rate on biopsy

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Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of DRE in respect to various PSA levels are summarized in [Table 3]. The PPV of DRE in various serum PSA levels was found to increase with increase in PSA levels, for example, the P PV was 41.93%, 54.41%, and 79.71% at PSA levels of 4–10.0, 10.01–20.0, >20.01 ng/ml, respectively. The PPV of DRE alone was 52.18% compared to 45.46% for serum PSA using a PSA value ≥4, and when both DRE and PSA ≥4 were used, the PPV increased to 67.83% [Figure 1].
Figure 1: Positive predictive value for detection of prostate cancer with respect to various parameters

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 > Discussion Top


Absolute eradication is futile, but detection at an early stage is the goal of every cancer screening test including the one for prostate cancer. Current established detection methods of prostate cancer include DRE, serum PSA, and TRUS-guided prostate biopsy using a systematic 12-core method; however, one aspect of prostate cancer screening that remains unsettled is the role of DRE. Before the era of serum PSA, DRE was once considered a cardinal method to screen for prostate cancer.[2]

Multiple studies and guidelines give conflicting opinions regarding the use of DRE as a screening tool.[5],[6] The NCCN guidelines, besides recommending DRE in cases with elevated PSA levels, also state that DRE may be considered as a baseline test in all patients due to its ability to detect high-grade cancer in the absence of PSA elevation.[7] The AUA found no evidence in support of DRE, whereas the ERSPC data revealed that abnormal rectal examination was associated with prostate cancer in the setting of elevated PSA.[5],[8] Recently, a study concluded that DRE demonstrated substantial prognostic utility for PSA >3, limited clinical utility when PSA <2, and some benefit in the setting of equivocal PSA 2–3.[14]

Recommendations regarding PSA cut-off value are also perplexing as with DRE. Whereas most guidelines use PSA ≥4 ng/ml for prostate cancer screening, the ERSPC and the prostate, lung, colorectal and ovarian (PLCO) cancer screening trial use serum PSA cut-offs between 2.5 and 4.0 ng/ml.[15],[16]

In our institute, we stipulated DRE in addition to PSA value ≥4 ng/ml as a screening method for carcinoma prostate followed by biopsy in positive patients. Given the lack of consensus regarding the utility of DRE for prostate cancer screening, we sought to evaluate the relationship between PSA and DRE from our institute's experience in a retrospective manner. DRE was done in all patients, irrespective of PSA. Our primary endpoint was to compare the efficacy of DRE and serum PSA in the detection of prostate cancer.

We acknowledged that the absolute risk of detection of cancer associated with a positive DRE is higher as PSA increases. Our study demonstrated that detection of tumors by DRE was significantly higher (52.18%) than by PSA (45.46%). Among positive biopsy patients, 5.75% were detected by DRE alone when the serum PSA level was normal (<4). PPV determines the percentage of cases actually having cancer when the detection method indicates a suspicious finding. Higher the PPV, lower the purposeless biopsies performed, hence we calculated PPV of DRE in respect to various PSA levels and found that PPV of DRE increases with increase in serum PSA levels. The PPV was 45.46% when PSA was elevated, 52.18% when DRE was suspicious, and 67.83% when both tests were used in combination.

Various studies show a wide variation in PPV of DRE and PSA level, so decision on whether to proceed with prostate biopsy must be individualized in every case as current established practice is that no PSA value exists that can establish with absolute certainty whether a patient does or does not have prostate cancer. Results from our study suggest that DRE should be included in prostate cancer screening as many patients with Ca prostate will remain undetected if we use PSA only.

Currently, various nomograms and predictive models have been developed to assist in this decision, but none have been able to provide a definite decision. With the introduction of various new markers such as prostate cancer gene 3 (PCA 3) and others, in the near future, we can more clearly identify patients at risk for prostate cancer before initial prostate biopsy.

Our results must be interpreted within the context of the study design, and few other points should be taken into account. Such as Such as PSA testing in our study was performed from different manufacturers (Laboratories) and various studies have shown significant differences in the numerical value of the PSA concentration when assays from different manufacturers(Laboratories) used.[17],[18] Therefore, it cannot be assumed that the PPVs and other findings will be replicated with assays from other manufacturers. Another point is that DRE was performed by several urology consultants and being a subjective finding, it limits the conclusion that we derive. For ethical reasons, none of the men with normal DRE and normal PSA findings underwent biopsy. Therefore, we have no data concerning false-negative results.


 > Conclusion Top


Suspicious DRE was significantly associated with detection of prostate cancer across all PSA levels. Patients with PSA <4 can harbor prostate malignancy and such cases can be detected by the use of DRE in screening of all patients. PSA and DRE should be used in combination for screening to increase detection of prostate cancer.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
 > References Top

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Chodak GW, Schoenberg HW. Early detection of prostate cancer by routinescreening. JAMA 1984;252:3261-4.  Back to cited text no. 2
    
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Timilsina BR, Devkota G, Giri S, Pradhan S, Raj S. Relationship of prostate specific antigen and digital rectal examination in prediction of prostate cancer. JCMS 2020;16:83-7.  Back to cited text no. 3
    
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Irekpita E, Achor GO, Alili U. Assessment of the value of the different variants of abnormal digital rectal examination finding in predicting carcinoma of the prostate: A preliminary report of two center study. Afr J Urol 2020;26:1-5.  Back to cited text no. 4
    
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Gosselaar C, Roobol MJ, Roemeling S, Schroder FH. The role of the digitalrectal examination in subsequent screening visits in the European randomized study of screening for prostate cancer (ERSPC), Rotterdam Eur Urol 2008;54:581-8.  Back to cited text no. 5
    
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Roobol MJ, van Vugt HA, Loeb S, Zhu X, Bul M, Bangma CH, et al. Prediction of prostate cancer risk: The role of prostate volume and digital rectal examination in the ERSPC risk calculators. Eur Urol 2012;61:577-83.  Back to cited text no. 6
    
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Carroll PR, Parsons JK, Andriole G, Bahnson RR, Castle EP, Catalona WJ, et al. NCCN guidelines insights: Prostate cancer early detection, version 2.2016. J Natl Comp Cancer Netw 2016;14:509-19.  Back to cited text no. 7
    
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Carter HB, Albertsen PC, Barry MJ, Etzioni R, Freedland SJ, Greene KL, et al. Early detection of prostate cancer: AUA Guideline. J Urol 2013;190:419-26.  Back to cited text no. 8
    
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Hodge KK, McNeal JE, Terris MK, Stamey TA. Random systematic versus directed ultrasound guided transrectal core biopsies of theprostate. J Urol 1989;142:71-5.  Back to cited text no. 9
    
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Watanabe H. History of ultrasound in nephrourology. Ultrasound Med Biol 2001;27:447-53.  Back to cited text no. 10
    
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Presti JC. Prostate biopsy: Current status and limitations. Rev Urol 2007;9:93-8.  Back to cited text no. 11
    
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Shariat SF, Roehrborn CG. Using biopsy to detect prostate cancer. Rev Urol 2008;10:262-80.  Back to cited text no. 12
    
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Prorok PC, Andriole GL, Bresalier RS, Buys SS, Chia D, Crawford ED, et al. Design of the prostate, lung, colorectal and ovarian (PLCO) cancer screening trial. Control Clin Trials 2000;21:273S-309S.  Back to cited text no. 13
    
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Halpern JA, Oromendia C, Shoag JE, Mittal S, Cosiano MF, Ballman KV, et al. Utility of digital rectal examination (DRE) as an adjunct to prostate specific antigen (PSA) in the detection of clinically significant prostate cancer. J Urol 2018;199:947-53.  Back to cited text no. 14
    
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Andriole GL, Levin DL, Crawford ED, Gelmann EP, Pinsky PF, Chia D, et al. Prostate cancer screening in the prostate, lung, colorectal and ovarian (PLCO) cancer screening trial: Findings from the initial screening round of a randomized trial. J Natl Cancer Inst 2005;97:433e8.  Back to cited text no. 15
    
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Schröder FH, Hugosson J, Roobol MJ, Tammela TL, Ciatto S, Nelen V, et al. Screening and prostate-cancer mortality in arandomized European study. N Engl J Med 2009;360:1320e8.  Back to cited text no. 16
    
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Zhou A, Tewari P, Bonacci M, Walsh R, Larsen F, Stamey T, et al. Complexation of prostate specific antigen (PSA) in serum. Clin Chem 1992;38:982.  Back to cited text no. 17
    
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Turkes A, Nott JP, Griffths K. Prostate-specific antigen: Problems in analysis. Eur J Cancer 1991;27:650.  Back to cited text no. 18
    


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