Repeat Biopsy Group Research Articles

Use of Prostate Specific Antigen Density Combined with Multiparametric Magnetic Resonance Imaging Improves Triage for Prostate Biopsy

Background: Multi-parametric magnetic resonance imaging (mpMRI)-directed biopsy for prostate cancer (PC) diagnosis improves the detection of clinically significant prostate cancer (CSPC) and decreases the rate of over-diagnosis of insignificant disease. The aim of this study was to investigate the value of mpMRI combined with prostate specific antigen density (PSAD) in the decision making related to the biopsy. Methods: mpMRI and mpMRI/transrectal ultrasound fusion targeted biopsies with subsequent systematic biopsies were performed in 397 patients (223 biopsy-naïve and 174 with a previous biopsy). Detection rates of (CSPC) and insignificant PC were stratified using the PIRADS score, and the number of avoidable biopsies and missed (CSPC) were plotted against PSAD values of 0.1–0.5 ng/mL². Results: PIRADS <3 and PSAD <0.2 ng/mL² were the safest criteria for not performing a biopsy. When applied to the biopsy-naïve group, 21.5% (48/223) of the biopsies could have been avoided and 3.7% (3/82) of CSPC would have been missed. In the repeat biopsy group, 12.6% (22/174) of biopsies could have been avoided and 6.9% (4/58) of (CSPC) would have been missed. Conclusions: A combination of mpMRI and PSAD might reduce the number of biopsies performed with the cost of missing <4% of CSPC.

Transrectal ultrasound-guided biopsy for prostate cancer detection: Systematic and/or magnetic-resonance imaging-targeted.

Magnetic resonance imaging (MRI) is being more widely used in the detection of prostate cancer (PCa), particularly after an initial negative biopsy. In this study, we compared 12-core systematic biopsy (SYS), MRI-targeted biopsy (TAR), and the association of systematic and MRI-targeted (SYS+TAR) prostate biopsy in patients with previous biopsy and those who were biopsy-naive to evaluate the differences in terms of cancer detection and clinically significant cancer detection between the three modalities. Overall, 203 consecutive patients with suspicion of PCa were analyzed; 48.2% were biopsy-naive and 51.7% had at least one previous negative prostate biopsy. The median age was 66 years, median prostate-specific antigen (PSA) level was 7.9 ng/mL and median prostate volume was 46 mL. 38.9% had SYS, 19.2% TAR only, and 41.8% had SYS+TAR biopsy. Overall, the PCa detection (PCaDR) was 63%. The SYS+TAR biopsy detected significantly more cancer than SYS and TAR only biopsies (72.9% vs. 56.9% and 53.8% respectively; p=0.03). Detection rate of clinically significant cancer (csPCaDR) was 50.7% overall; 65.8% in the SYS+TAR biopsy vs. 39.2% in the SYS and 48.7% in the TAR groups (p=0.002). In the biopsy-naive group, PCaDR and csPCaDR were significantly higher in the SYS+TAR group than in the SYS and TAR groups (p=0.01). In the repeat biopsy group, PCaDR and csPCaDR were equivalent in the TAR and SYS+TAR groups and higher than in the SYS group (p=0.001). TAR biopsy, when added to SYS biopsy, was associated with a higher detection rate of csPCa in biopsy-naive patients when compared to TAR and SYS only biopsies. In patients after previous negative biopsy, detection rates of csPCa were equivalent for SYS+TAR and TAR only biopsies, but higher than SYS.

Repeat biopsy of primary disease negatively affects the outcome of patients with nasopharyngeal cancer treated with definitive intensity-modified radiotherapy: a cohort analysis of 795 patients.

To determine whether pretreatment repeat biopsy of nasopharynx is associated with an impaired outcome in nasopharyngeal carcinoma patients in an intensity-modified radiotherapy era. We performed a retrospective data review of the association between pretreatment nasopharyngeal biopsy and outcomes for all nasopharyngeal carcinoma patients treated at our center between January 2007 and December 2011. Of the 720 patients enrolled, 693 (96.3%) were diagnosed after initial biopsy and 27 (3.7%) after repeat biopsy. Five-year cancer-specific survival, disease-free survival and distant metastasis-free survival for the two groups were compared using univariate and multivariate analyses to evaluate the effects of repeat biopsy on the outcome. Five-year estimated cancer-specific survival (75.9 vs. 88.5%, P= 0.045) and disease-free survival (63.3 vs. 77.1%, P= 0.041) were significantly poorer in the repeat biopsy group than the initial biopsy group. After adjustment for other prognostic factors (age, gender, T and N stage), pretreatment biopsy remained independently associated with poorer both 5-year cancer-specific survival and disease-free survival. The hazard ratios for cancer-specific survival and disease-free survival in the repeat biopsy group were 2.73 (95% confidence interval 1.09-6.82) and 2.22 (95% confidence interval 1.12-4.37) compared with the initial biopsy group (reference), respectively. The repeat biopsy group also had a higher risk of distant failure compared with the initial biopsy group (hazard ratio 2.82, 95% confidence interval 1.22-6.51, P= 0.015). Pretreatment repeat biopsy of nasopharynx has a detrimental effect on survivals of nasopharyngeal carcinoma patients, which may be partly due to an increased frequency of distant metastasis.

Can urinary PCA3 supplement PSA in the early detection of prostate cancer?

Given the limited sensitivity and specificity of prostate-specific antigen (PSA), its widespread use as a screening tool has raised concerns for the overdiagnosis of low-risk and the underdiagnosis of high-grade prostate cancer. To improve early-detection biopsy decisions, the National Cancer Institute conducted a prospective validation trial to assess the diagnostic performance of the prostate cancer antigen 3 (PCA3) urinary assay for the detection of prostate cancer among men screened with PSA. In all, 859 men (mean age, 62 years) from 11 centers scheduled for a diagnostic prostate biopsy between December 2009 and June 2011 were enrolled. The primary outcomes were to assess whether PCA3 could improve the positive predictive value (PPV) for an initial biopsy (at a score > 60) and the negative predictive value (NPV) for a repeat biopsy (at a score < 20). For the detection of any cancer, PPV was 80% (95% CI, 72% to 86%) in the initial biopsy group, and NPV was 88% (95% CI, 81% to 93%) in the repeat biopsy group. The addition of PCA3 to individual risk estimation models (which included age, race/ethnicity, prior biopsy, PSA, and digital rectal examination) improved the stratification of cancer and of high-grade cancer. These data independently support the role of PCA3 in reducing the burden of prostate biopsies among men undergoing a repeat prostate biopsy. For biopsy-naive patients, a high PCA3 score (> 60) significantly increases the probability that an initial prostate biopsy will identify cancer.

Abstract 4451: The NCI Early Detection Research Network (EDRN) urinary PCA3 validation trial

Abstract INTRODUCTION: Widespread use of PSA screening has raised concerns of overdiagnosis of low risk and underdiagnosis of high grade cancer. This is primarily due to the low sensitivity and specificity of PSA. PCA3, a non-coding large chain ribonucleic acid, is significantly over-expressed in cancer tissue and quantitatively measured by a novel urinary assay. The objective of this NCI EDRN trial was to conduct a comprehensive, independent validation of the PROGENSA PCA3 Assay for the detection of prostate cancer. METHODS: A prospective, PROBE-compliant NCI validation trial was undertaken at 11 clinical sites to evaluate PCA3 positive predictive value (PPV, PCA3 score &amp;gt;60) in the initial biopsy setting and negative predictive value (NPV, PCA3 score &amp;lt;20) in the repeat biopsy setting. PCA3 was obtained prior to biopsy but following an attentive DRE. We hypothesized that PPV for an initial prostate biopsy to be at least 55% and that NPV for a repeat biopsy to be at least 75%. The accuracy of PCA3 in detecting any prostate cancer and secondarily, high grade cancer (Gleason &amp;gt; 7), was compared to PCPT risk calculator through ROC curve analysis. RESULTS: 880 eligible men (mean age 62 years) were enrolled; 305 had a prior negative prostate biopsy. 99% had an informative PCA3 test. For the detection of any cancer, PPV was 80% (95% CI: 0.72 - 0.86) in the initial biopsy group while NPV was 88% (95% CI: 0.81 - 0.93) in the repeat biopsy group. PCA3 performance was superior to PCPT risk estimation and improved upon the detection of any cancer (p&amp;lt;0.006) and high grade cancer (p&amp;lt;0.02) when combined with the PCPT risk model. CONCLUSIONS: PCA3 ability to detect prostate cancer was superior to PCPT risk calculator in both the initial (p &amp;lt; 0.0001) and repeat biopsy setting (p=0.001)Independent validation of PCA3 demonstrated a high PPV in the initial biopsy setting and a high NPV in the repeat biopsy setting. Given the significant improvements in risk estimation over PCPT, PCA3 is expected to greatly enhance clinical decision making. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4451. doi:1538-7445.AM2012-4451

2206 THE NCI EARLY DETECTION RESEARCH NETWORK (EDRN) URINARY PCA3 VALIDATION TRIAL

You have accessJournal of UrologyProstate Cancer: Detection and Screening V1 Apr 20122206 THE NCI EARLY DETECTION RESEARCH NETWORK (EDRN) URINARY PCA3 VALIDATION TRIAL John Wei, Martin Sanda, Ian Thompson, Alan Partin, Zideng Feng, Lori Sokoll, Jack Groskopf, Elissa Brown, Yair Lotan, Adam Kibel, Erik Busby, Mohamed Bidair, Dan Lin, Samir Taneja, and Rosalia Viterbo John WeiJohn Wei Ann Arbor, MI More articles by this author , Martin SandaMartin Sanda Boston, MA More articles by this author , Ian ThompsonIan Thompson San Antonio, TX More articles by this author , Alan PartinAlan Partin Baltimore, MD More articles by this author , Zideng FengZideng Feng Seattle, WA More articles by this author , Lori SokollLori Sokoll Baltimore, MD More articles by this author , Jack GroskopfJack Groskopf San Diego, CA More articles by this author , Elissa BrownElissa Brown Seattle, WA More articles by this author , Yair LotanYair Lotan Dallas, TX More articles by this author , Adam KibelAdam Kibel St. Louis, WA More articles by this author , Erik BusbyErik Busby Birmingham, AL More articles by this author , Mohamed BidairMohamed Bidair San Diego, CA More articles by this author , Dan LinDan Lin Seattle, WA More articles by this author , Samir TanejaSamir Taneja New York City, NY More articles by this author , and Rosalia ViterboRosalia Viterbo Philadelphia, PA More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2012.02.2381AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Widespread use of PSA screening has raised concerns of overdiagnosis of low risk and underdiagnosis of high grade cancer. This is primarily due to the low sensitivity and specificity of PSA. PCA3,a non-coding large chain ribonucleic acid, is significantly over-expressed in cancer tissue and quantitatively measured by a novel urinary assay. The objective of this NCI EDRN trial was to conduct a comprehensive, independent validation of the PROGENSA PCA3 Assay for the detection of prostate cancer. METHODS A prospective, PROBE-compliant NCI validation trial was undertaken at 11 clinical sites to evaluate PCA3's positive predictive value (PPV, PCA3 score >60) in the initial biopsy setting and negative predictive value (NPV, PCA3 score <20) in the repeat biopsy setting. PCA3 was obtained prior to biopsy but following an attentive DRE. We hypothesized that PPV for an initial prostate biopsy to be at least 55% and that NPV for a repeat biopsy to be at least 75%.The accuracy of PCA3 in detecting any prostate cancer and secondarily, high grade cancer (Gleason > 7),was compared to PCPT risk calculator through ROC curve analysis. RESULTS 880 eligible men (mean age 62 years) were enrolled; 305 had a prior negative prostate biopsy. 99% had an informative PCA3 test. For the detection of any cancer, PPV was 80% (95% CI: 0.72–0.86) in the initial biopsy group while NPV was 88%(95% CI: 0.81–0.93) in the repeat biopsy group. PCA3 performance was superior to PCPT risk estimation (see Figures) and improved upon the detection of any cancer (p<0.006) and high grade cancer (p<0.02) when combined with the PCPT risk model. CONCLUSIONS Independent validation of PCA3 demonstrated a high PPV in the initial biopsy setting and a high NPV in the repeat biopsy setting. Given the significant improvements in risk estimation over PCPT, PCA3 is expected to greatly enhance clinical decision making. Figure: PCA3 ability to detect prostate cancer was superior to PCPT risk calculator in both the initial (Figure 1, p < 0.0001) and repeat biopsy setting (Figure 2, p=0.001) © 2012 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 187Issue 4SApril 2012Page: e889-e890 Advertisement Copyright & Permissions© 2012 by American Urological Association Education and Research, Inc.MetricsAuthor Information John Wei Ann Arbor, MI More articles by this author Martin Sanda Boston, MA More articles by this author Ian Thompson San Antonio, TX More articles by this author Alan Partin Baltimore, MD More articles by this author Zideng Feng Seattle, WA More articles by this author Lori Sokoll Baltimore, MD More articles by this author Jack Groskopf San Diego, CA More articles by this author Elissa Brown Seattle, WA More articles by this author Yair Lotan Dallas, TX More articles by this author Adam Kibel St. Louis, WA More articles by this author Erik Busby Birmingham, AL More articles by this author Mohamed Bidair San Diego, CA More articles by this author Dan Lin Seattle, WA More articles by this author Samir Taneja New York City, NY More articles by this author Rosalia Viterbo Philadelphia, PA More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Differences in Postoperative Pathological Outcomes between Prostate Cancers Diagnosed at Initial and Repeat Biopsy

PurposeWe evaluated the differences in pathological outcomes between prostate cancers (PCas) diagnosed at initial and repeat biopsy.Materials and MethodsWe retrospectively reviewed the medical records of 287 patients who underwent radical retropubic prostatectomy from 2005 to 2010. We investigated preoperative factors, such as age, serum prostate-specific antigen (PSA), prostate volume (PV), digital rectal examination (DRE) results, biopsy schema, clinical stage, and number of prior biopsies, and postoperative pathological outcomes, including specimen volume, percent tumor volume, Gleason score (GS), tumor bilaterality, pathological stage, positive surgical margin (PSM), lymphovascular invasion (LVI), and perineural invasion (PNI). Patients were then classified into two groups by the number of prior biopsies (initial biopsy vs. repeat biopsy). We compared preoperative factors and postoperative pathological outcomes between the two groups.ResultsOf the 287 patients, 246 (85.7%) were diagnosed with cancer at the initial biopsy and 41 (14.3%) at the repeat biopsy. The repeat biopsy group was older (p=0.048), had a larger PV (p=0.009), had a significantly different biopsy schema (p<0.001), and had a lower (<10%) percentage tumor volume (p=0.016). In the multivariate analysis (after adjustment for biopsy schema, age, serum PSA, PV, and DRE), repeat biopsy was not an independent predictor of GS, tumor bilaterality, pathological stage, PSM, LVI, or PNI (p=0.212, 0.456, 0.459, 0.917, 0.991 and 0.827, respectively), but repeat biopsy could predict lower percentage tumor volume (p=0.037).ConclusionsThe pathological outcomes of PCas detected at repeat biopsy were not significantly different from those of PCas detected at initial biopsy except for a lower (<10%) percentage tumor volume.

Using a Saturation Biopsy Scheme Increases Cancer Detection During Repeat Biopsy in Men With High-grade Prostatic Intra-epithelial Neoplasia

To determine the role of transrectal saturation biopsy for cancer detection in men with high-grade prostatic intra-epithelial neoplasia (HGPIN) diagnosed by extended biopsy. HGPIN was clearly associated with cancer risk in the sextant biopsy era, but this has not been clearly demonstrated in the extended biopsy era. From 1999 to 2009, 314 men had at least 1 or more repeat biopsy due to the presence of exclusive HGPIN (without any other pathologic finding) in a previous extended biopsy. They were divided into 2 groups according to the initial follow-up biopsy scheme, 178 men were followed up using a second standard extended biopsy scheme and 136 were followed up using the saturation biopsy scheme. In the standard repeat biopsy group, 35 of 178 (19.7%) men had cancer on initial repeat biopsy. In the saturation biopsy group, 42 of 136 (30.9%) had cancer on initial repeat biopsy (overall, P = .04). Multivariate analysis demonstrates that the biopsy scheme on repeat biopsy is an independent predictor of prostate cancer detection (OR 1.85, (95% CI; 1.03, 3.29), exclusive of age, PSA, days from initial biopsy, DRE status and multifocal PIN. Furthermore, there appears to be no further increase in Gleason 6 disease with usage of saturation biopsy in this unique population. Cancer detection in men with HGPIN in the contemporary extended biopsy era is substantially improved using saturation technique.

The value of an artificial neural network in the decision-making for prostate biopsies

In majority of patients who are subjected to prostate biopsies, no prostate cancer (PCa) is found. It is important to prevent unnecessary biopsies since serious complications may occur. An artificial neural network (ANN) may be able to predict the risk of the presence of PCa. Included were all patients, who underwent transrectal ultrasound-guided prostate biopsies between June 2006 and June 2007 with a total PSA (tPSA) level between 2 and 20 microg/l. The patients were divided into two groups according to their tPSA level (2-10 microg/l and 10-20 microg/l). The ANN Prostataclass of the Universitätsklinikum Charité in Berlin was used. The predictions of the ANN were compared to the pathology results of the biopsies. Overall 165 patients were included. PCa was diagnosed in 53 patients, whereas the ANN predicted "no risk" in 19 of these patients (36%). The ANN output receiver operator characteristic (ROC) plots for the range of tPSA 2-10 microg/l and tPSA 10-20 microg/l showed an area under the curve (AUC) of 63 and 88% for the initial biopsy group, versus 69 and 57%, respectively, for the repeat biopsy group. The ANN resulted in a false negative rate of 36%, missing PCa in 19 patients. For use in an outpatient-clinical setting, this ANN is insufficient to predict the risk of presence of PCa reliably.

Risk of prostate cancer after detection of isolated high-grade prostatic intraepithelial neoplasia (HGPIN) on extended core needle biopsy: a UK hospital experience

BackgroundHigh-grade prostatic intraepithelial neoplasia (HGPIN) is a precursor lesion to prostate cancer (CaP). UK-based studies examining the occurrence of isolated HGPIN and subsequent risk of CaP are lacking. Our aim was to assess the occurrence of HGPIN in a regional UK population and to determine whether in a retrievable cohort of such patients that had repeat extended core biopsies, there was an elevated risk of CaP.MethodsA retrospective analysis of the pathology database was conducted at our institution (Lancashire Teaching Hospitals NHS Foundation Trust) for prostate biopsies recorded between January 2001 and December 2005 (all extended core biopsies). Those patients with isolated HGPIN on 1st set of biopsies were identified and, their clinical characteristics and pathological findings from subsequent biopsies (if any) were determined. The risk of CaP on subsequent biopsies based on presenting baseline PSA was stratified.ResultsOf 2,192 biopsied patients, there were 88 cases of isolated HGPIN of which 67 patients underwent one or more repeat biopsies. In this repeat-biopsy group, 28 CaP diagnoses were made. Age at first biopsy (P < 0.001), higher mean baseline prostate-specific antigen (PSA) (P < 0.005) and higher mean change in PSA (P < 0.05) were predictive of CaP detection on repeat biopsies. PSA ranges and their associated predictive values for cancer were: 0 to 5 ng/ml – 11%; 5 to 10 ng/ml – 34%; 10 to 20 ng/ml – 50%; and > 20 ng/ml – 87.5%.ConclusionBased on our results, we recommend delaying the 1st repeat biopsy at low PSA range but to have a shorter interval to repeat biopsies at intermediate and higher PSA ranges.

Predictors of prostate cancer on repeat prostatic biopsy in men with serum total prostate‐specific antigen between 4.1 and 10 ng/mL

We determine whether the different molecular forms of prostate-specific antigen (PSA) and other PSA variables can predict prostate cancer in men undergoing repeat prostate needle biopsy. Between 1997 and 2001, repeat biopsy was performed in 97 patients who had undergone prior negative prostate biopsy. The ability of total PSA (tPSA), complexed PSA (cPSA), free PSA (fPSA), free-to-total PSA (fPSA/tPSA), free-to-complexed PSA (fPSA/cPSA), complexed-to-total PSA (cPSA/tPSA), tPSA density (tPSAD), cPSA density (cPSAD), transition zone tPSA density (tPSATZ) and transition zone cPSA density (cPSATZ) was assessed by univariate and multivariate analyzes as well as receiver operating characteristics (ROC) curves. Prostate cancer on repeat biopsy was detected in 24% of subjects (23 of 97) who had a negative initial biopsy. The PSA parameters cut-off to ensure a 96% sensitivity of cancer detection, were 29% using fPSA/tPSA, 32% using fPSA/cPSA, 0.18 ng/mL/cc using tPSATZ and 0.16 ng/mL/cc using cPSATZ. The fPSA/tPSA would have prevented 32% of negative biopsies, the fPSA/cPSA 28%, the tPSATZ 23% and the cPSATZ 30%. ROC curve analysis fPSA/tPSA, fPSA/cPSA ratios, tPSATZ and cPSATZ were significantly better predictors of repeat biopsy results than tPSA or cPSA, but there was no significant difference in the ROC curves among these four PSA parameters. In the multivariate logistic regression analysis these four PSA parameters were significant predictors for cancer detection in the repeat biopsy group (P < 0.001). fPSA/tPSA ratio, fPSA/cPSA ratio, tPSATZ and cPSATZ enhance the specificity of PSA testing compared to tPSA or cPSA when determining which patients should undergo repeat biopsy.

The necessity of a second prostate biopsy cannot be predicted by PSA or PSA derivatives (density or free:total ratio) in men with prior negative prostatic biopsies

Serum prostate specific antigen, prostate specific antigen density and free:total prostate specific antigen are known to be useful for determining the risk of prostate cancer in patients undergoing prostate cancer screening. The patient with a positive biopsy presents no future prostate specific antigen dilemma. Those with negative biopsies often go on to numerous repeat biopsies. Our goal was to establish criteria that could be used to identify patients who will require repeat prostate biopsies (possibly false negative initial biopsy), while not exposing the low risk population (probable true negative initial biopsy) to additional invasive procedures. Between March 1991 and March 1998, 148 patients who had a biopsy for an elevated prostate specific antigen value (4.1-10.0) or an altered digital rectal examination, had no cancer found in the specimen. From these, 51 (34.4%) had repeated biopsies, while the others persisted on close follow-up. We examined their serum prostate specific antigen, prostate specific antigen density and free:total prostate specific antigen value, as well as their age and histology results of the initial and repeat biopsy, to determine if any predictor of the need for a repeat biopsy could be identified. Eight (15.7%) from 51 men who had repeat biopsy had prostate cancer detected. Forty three (84.3%) patients persisted with a negative biopsy, despite filling the criteria for re-biopsy. Multivariate analysis failed to identify any significant predictors of prostate cancer in the repeat biopsy group. Despite initial success, the prostate specific antigen derivatives and free:total prostate specific antigen have not safely limited the number of biopsies performed for an abnormal prostate specific antigen (4.1-10.0). Neither prostate specific antigen density nor free:total prostate specific antigen predicted the need for repeat biopsy in this specific group. The results of this ongoing study demonstrate that to date, prostate specific antigen and prostate specific antigen derivatives can not be utilized to determine which patients will be at high risk for requiring repeat prostate biopsy. All patients must be closely monitored for evidence of a change in status from benign to malignant disease, and new markers for this purpose are urgently needed.

Flow Cytometry of Fine Needle Aspirations of the Sprague-Dawley Rat Testis: Defining Normal Maturation and the Effects of Multiple Biopsies

Quantitative assessment of spermatogenesis by flow cytometry reproducibly correlates with histological examination. Flow cytometry of fine needle aspirates from the testis was used to analyze normal spermatogenesis of Sprague-Dawley rats. Aged matched male weanlings were divided into 3 groups: group 1—5 rats underwent bilateral percutaneous aspiration of the testes with a 22 gauge Chiba needle on postpartum days 19, 24, 30 and 40; group 2—5 rats aspirated on days 24, 30 and 40, and group 3—4 rats aspirated on days 30 and 40. This sequential approach allowed for evaluation of normal spermatogenesis and the effects of repeated fine needle aspiration on spermatogenesis.Deoxyribonucleic acid distribution analysis by flow cytometry correlates with haploid (IN), diploid (2N), tetraploid (4N) and S phase cell populations. These cell populations were evaluated and comparisons among each group were made at all biopsy times. No significant differences in mean 2N, 4N or S phase cell populations in single versus repeat biopsied testes were detected. However, there was a significant increase in the IN population at 30 days post partum in the repeat biopsy group (p = 0.037), which normalized by day 40. This increase in 1N corresponds to the beginning of meiosis, which is maximal between postpartum days 30 and 40, and occurs earlier in the repeat biopsied testis. Repeat fine needle aspiration of the testis can be performed without significantly affecting spermatogenesis in the “weanling” rat. This provides a useful technique in the future investigations of the time related effects of varicocele, chemotherapy and toxicologic drugs on spermatogenesis.