Improved sensitivity for detecting micrometastases in pelvic lymph nodes by real-time reverse transcriptase polymerase chain reaction (RT-PCR) compared with conventional RT-PCR in patients with clinically localized prostate cancer undergoing radical prostatectomy

Prediction of Biochemical Recurrence Based on Molecular Detection of Lymph Node Metastasis After Radical Prostatectomy

Background

Molecular detection of lymph node (LN) micrometastases by analyzing mRNA expression of epithelial markers in prostate cancer (PC) patients provides higher sensitivity than histopathological examination.

Objective

To investigate which type of marker to use and whether molecular detection of micrometastases in LNs was predictive of biochemical recurrence.

Design, setting, and participants

LN samples from PC patients undergoing radical prostatectomy with extended LN dissection between 2009 and 2011 were examined for the presence of micrometastases by both routine histopathology and molecular analyses.

Outcome measurements and statistical analysis

The mRNA expression of a panel of markers of prostate epithelial cells, prostate stem cell–like cells, epithelial-to-mesenchymal transition, and stromal activation, was performed by quantitative real-time polymerase chain reaction. The expression levels of these markers in LN metastases from three PC patients were compared with the expression levels in LN from five control patients without PC in order to identify the panel of markers best suited for the molecular detection of LN metastases. The predictive value of the molecular detection of micrometastases for biochemical recurrence was assessed after a follow-up of 10 yr.

Results and limitations

Prostate epithelial markers are better suited for the detection of occult LN metastases than molecular markers of stemness, epithelial-to-mesenchymal transition, or reactive stroma. An analysis of 1023 LNs from 60 PC patients for the expression of prostate epithelial cell markers has revealed different expression levels and patterns between patients and between LNs of the same patient. The positive predictive value of molecular detection of occult LN metastasis for biochemical recurrence is 66.7% and the negative predictive value is 62.5%. Limitations are sample size and the hypothesis-driven selection of markers.

Conclusions

Molecular detection of epithelial cell markers increases the number of positive LNs and predicts tumor recurrence already at surgery.

Patient summary

We show that a panel of epithelial prostate markers rather than single genes is preferred for the molecular detection of lymph node micrometastases not visible at histopathological examination.

Surgery for pathological T3a, T3b and lymph node positive, prostate cancer: surgical, functional and oncological outcomes

Objective:

To investigate and document the surgical, functional and oncological outcomes following surgery for high-risk prostate cancer patients.

Patients and methods:

Patients with pathological T3a, T3b and N1 disease were extracted from our prospectively updated institutional database. Data include demographics, preoperative cancer parameters, short and long-term complications and functional results. Details of biochemical recurrence, type and oncological outcome of salvage treatments, cancer-specific and overall survival were also obtained.

Results:

A total of 669 patients were included; 58.9% had T3a disease, 35.9% had pT3b and 11.4% N1 disease. With a median follow-up of 66 months (8–129), overall survival was 94.3%, cancer-specific survival was 98.7% and biochemical recurrence was 45.6%. Average inpatient stay was 1 day and the overall complication rate was 9.1%; 54.2% experienced a biochemical recurrence and 90.3% went on to have one or more salvage treatments, which were varied. Significant predictors of biochemical recurrence included pathological stage, any positive margin and patient age ( P<0.005). A total of 44.9% had an immediate biochemical recurrence, with 90% receiving subsequent treatment and 20.5% having a durable response. None of the patients receiving prostate bed radiotherapy alone had a durable response. 54% had a delayed biochemical recurrence, with 63.5% receiving subsequent treatment and 44% having a durable response.

Conclusions:

Surgery is associated with encouraging surgical and functional outcomes, cancer-specific survival and overall survival rates in these patients. Pathological stage is a significant predictor of biochemical recurrence. The present analysis shows that long-term observation for certain patients with biochemical recurrence is appropriate and questions the effectiveness of further local salvage treatments in patients with an immediate biochemical recurrence postoperatively.

Level of evidence:

II

Detection of CK19 mRNA Using One-step Nucleic Acid Amplification (OSNA) in Prostate Cancer: Preliminary Results

Background: Accurate histopathological evaluation of lymph nodes (LNs) is essential for reliable staging in prostate cancer. In routine practice, conventional techniques only examine parts of the LN. Molecular nodal staging methods are limited by their high costs and extensive time requirement. One-step nucleic acid amplification (OSNA) determines the metastatic status of the complete LN and allows for rapid intraoperative detection of LN metastases. OSNA has been proposed for diagnosis of LN metastases from breast cancer by quantifying the CK19 mRNA copy number. To provide basic data for OSNA development for prostate cancer, we conducted an investigation of CK19 and OSNA in prostate cancer specimens.

Methods: OSNA is based on a short homogenization step and subsequent automated amplification of CK19 mRNA directly from the sample lysate, with results available in 30-40 min. A total of 20 prostate cancer specimens from consecutive patients with intermediate or high-risk prostate cancer (Gleason-Score ≥7) were investigated by both OSNA and conventional histopathology (H&E staining, CK19 immunohistochemistry). OSNA was performed on frozen samples using a ready-to-use amplification kit in an automated real-time detection system. Samples were defined as 'negative' or 'positive' according to mRNA copy number: >5000 copies/µl (++), 250-5000 copies/µl (+), and <250 copies/µl (-).

Results: Histopathological analysis confirmed prostate cancer in all samples: Gleason score 7 (n=11), Gleason score 8 (n=2), and Gleason score 9 (n=6). Gleason score could not be given for one patient who previously underwent hormonal treatment. OSNA analysis detected CK19 expression in 100% of the specimens and high numbers of CK19 mRNA copies in all cases (9 samples ++; 11 samples +). Immunohistochemistry confirmed CK19 expression in 19 of 20 cases. In the immunohistochemistry CK19-negative patient, a Gleason score 9 prostate cancer was diagnosed.

Conclusions: This is the first study using OSNA to detect CK19 expression in prostate cancer. Initial data indicate that this rapid method for molecular LN staging reliably identifies CK19 mRNA in prostate cancer. These results suggest that the OSNA assay may be suitable to improve (intraoperative) LN staging in prostate cancer. For further verification, OSNA analysis of LN specimens from prostate cancer patients is required.

Update on histopathological evaluation of lymphadenectomy specimens from prostate cancer patients

BACKGROUND

Metastases to lymph nodes (LNs) represent an unfavorable prognostic factor in patients with prostate cancer (PCa). Histological examination represents the gold standard in the evaluation of the lymphadenectomy (LND) specimens for the presence of secondary deposits.

METHODS AND RESULTS

The metastatic detection rate can vary according to the approach adopted in the microscopic analysis of the LNs, which includes frozen-section examination, total inclusion of the tissue with and without whole-mount sections, serial sectioning, and the application of immunohistochemistry. The assessment of the sentinel LN, the search for micrometastases, and the evaluation of atypical LN metastatic sites further contribute to the detection of the metastatic spread.

CONCLUSION

In this review, an update on the histopathological evaluation of LND specimens in patients with PCa is given, and focus is made on their clinical and prognostic significance.

Detection of pelvic lymph node micrometastasis by real-time reverse transcriptase polymerase chain reaction in prostate cancer patients after hormonal therapy

OBJECTIVE

To determine the feasibility of prostatic-specific antigen (PSA) mRNA and prostatic-specific membrane antigen (PSMA) mRNA measurement in detection of pelvic lymph node (PLN) micrometastasis for prostate cancer (PCa) after hormonal therapy (HT).

METHODS

Fifty-four patients diagnosed as high risk localized PCa were given HT for 3 months before radical prostatectomy. Under bipedal lymphangiography, a needle was punctured into involved lymph nodes (LN) and aspirated lymphatic fluid was obtained preoperatively. The expression of PSA mRNA and PSMA mRNA in aspirated fluid was assessed by a fully quantitative real-time reverse transcriptase polymerase chain reaction (RT-PCR) and also in LN specimens from pelvic lymphadenectomy during prostatectomy.

RESULTS

Median follow-up was 36 months (range 18-58 months). Without histological evidence of PLN metastasis, twelve patients showed positive PSA and/or PSMA mRNA expressions and regarded as having micrometastases to PLNs. Biochemical recurrence (BCR) rate and interval between prostatectomy and BCR in patients with micrometastases (group B) were not significantly different to histologically proven PLN metastatic patients (group A) (58.3 vs. 83.3 %, P = 0.26; 10.9 vs. 9.2 months, P = 0.29, respectively), but significantly different to those with no PLN involvement (group C) (58.3 vs. 11.1 %, P = 0.002; 10.9 vs. 21.3 months, P < 0.001, respectively). Kaplan-Meier analysis showed both groups A and B had significantly lower non-BCR rate than group C (P < 0.001, P < 0.001, respectively).

CONCLUSIONS

For PCa patients receiving HT, measurement of PSA mRNA and PSMA mRNA in aspirated PLN fluid by real-time RT-PCR could effectively detect PLN micrometastases without surgical intervention.

Lymph node-positive prostate cancer: current issues, emerging technology and impact on clinical outcome

Lymph node metastasis in patients with prostate cancer indicates a poorer prognosis compared with patients without lymph node metastasis; however, some patients with node-positive disease have long-term survival. Many studies have attempted to discern what characteristics of lymph node metastasis are prognostically significant. These characteristics include nodal tumor volume, number of positive lymph nodes, lymph node density, extranodal extension, lymphovascular invasion and tumor dedifferentiation. Favorable characteristics of regional lymph node involvement included a smaller tumor size and smaller tumor volume. However, the current staging system for prostate cancer does not provide different subclassifications for patients with node-positive prostate cancer. In recent years numerous advanced technologies for the detection of lymph node metastasis have been developed, including molecular imaging techniques and the CellSearch Circulating Tumor Cell System. With the increased detection of patients with prostate cancer, emergence of new technology to identify lymph node metastasis and the number of radical prostatectomies being performed on the rise, subclassifying patients with lymph node-positive disease is imperative. Subclassification would provide a better picture of patient prognosis and allow for a better understanding of targeted therapies to treat patients with lymph node metastasis.

Sense and nonsense of an extended pelvic lymph node dissection in prostate cancer

Lymph node metastases associated with prostate cancer (PCa) has been shown to be a poor prognostic factor. The role of pelvic lymph node dissection (PLND) itself in relation to survival remains unclear, however. A Medline search was conducted to address this issue. The following conclusions were drawn. Only recently, improved survival due to completion of radical prostatectomy (RP) (compared to abandoning RP) in known or presumed lymph-node-positive patients has been shown. Lymph node sampling can only be considered representative if an adequate number of nodes is removed. While several authors have suggested that a therapeutic benefit in patients undergoing RP is not provided by PLND, the reliability of these studies is uncertain. Contrary to this, several studies have indicated the possibility of long-term survival even in the presence of limited lymph node metastases. The role and timing of initiation of adjuvant androgen deprivation therapy (ADT) in patients who have node-positive disease after RP is controversial. Recent studies suggest that delaying ADT may not adversely impact survival.

Role of pelvic lymph node dissection in prostate cancer treatment

Pelvic lymph node dissection (PLND) is the most accurate and reliable staging procedure for detecting lymph node invasion (LNI) in prostate cancer. Recently, [(11)C]-choline positron emission tomography imaging and magnetic resonance imaging with lymphotropic superpara-magnetic nanoparticles have shown potential for detecting LNI but are still under investigation. The risk of LNI in low-risk groups could be underestimated by use of the current nomograms, which rely on data collected from patients who underwent only limited PLND. Extended PLND (ePLND) shows higher lymph node yield, which leads to the removal of more positive nodes and fewer missed positive nodes. It may be possible to refrain from performing PLND on low-risk patients with a prostate-specific antigen value <10 ng/ml and a biopsy Gleason score ≤6, but the risk of biopsy-related understaging should be kept in mind. Theoretically, meticulous ePLND may also impact prostate cancer survival by clearing low-volume diseases and occult micrometastasis even in pN0. The therapeutic role of PLND in prostate cancer patients is still an open question, especially in individuals with low-risk disease. Patients with intermediate- to high-risk disease are more likely to benefit from ePLND.

Complete PSA Remission without Adjuvant Therapy after Secondary Lymph Node Surgery in Selected Patients with Biochemical Relapse after Radical Prostatectomy and Pelvic Lymph Node Dissection

Introduction. To evaluate whether secondary resection of lymph node (LN) metastases (LNMs) can result in PSA remission, we analysed the PSA outcome after resection of LNM detected on PET/CT in patients with biochemical failure. Materials and Methods. 11 patients with PSA relapse (mean 3.02 ng/mL, range 0.5-9.55 ng/mL) after radical prostatectomy without adjuvant therapy were included. Suspicious LN (1-3) detected on choline PET/CT and nearby LN were openly dissected (09/04-02/11). The PSA development was examined. Histological and PET/CT findings were compared. Results. 9 of 10 patients with histologically confirmed LNM showed a PSA response. 4 of 9 patients with single LNM had a complete permanent PSA remission (mean followup 31.8, range 1-48 months). Of metastasis-suspicious LNs (14) 12 could be histologically confirmed. The additionally removed 25 LNs were all correctly negative. Conclusions. The complete PSA remissions after secondary resection of single LNM argue for a feasible therapeutic benefit without adjuvant therapy. For this purpose the choline PET/CT is in spite of its limitations currently the most reliable routinely available diagnostic tool.

The extent of pelvic lymph node dissection correlates with the biochemical recurrence rate in patients with intermediate- and high-risk prostate cancer

OBJECTIVE

• To assess the impact of pelvic lymph node dissection (PLND) and of the number of lymph nodes (LNs) retrieved during radical prostatectomy (RP) on biochemical relapse (BCR) in pNX/0/1 patients with prostate cancer according to the clinical risk of lymph node invasion (LNI).

PATIENTS AND METHODS

• We evaluated 872 pT2-4 NX/0/1 consecutive patients submitted to RP between October 1995 and June 2009, with the following inclusion criteria: (i) a follow-up period ≥12 months; (ii) the avoidance of neoadjuvant hormonal therapy or adjuvant hormonal and/or adjuvant radiotherapy; (iii) the availability of complete follow-up data; (iv) no pathological T0 disease; (v) complete data regarding the clinical stage and Gleason score (Gs), the preoperative prostate-specific antigen (PSA) level and the pathological stage. • The patients were stratified as having low risk (cT1a-T2a and cGs ≤6 and PSA level < 10 ng/mL), intermediate risk (cT2b-T2c or cGs = 7 or PSA level = 10-19.9) or high risk of LNI (cT3 or cGs = 8-10 or PSA level ≥ 20). • The 872 patients were divided into two LN groups according to the number of LNs retrieved: group 1 had no LN or one to nine LNs removed; group 2 had 10 or more LNs. • The variables analysed were LN group, age, PSA level, clinical and pathological stage and Gs, surgical margin status, LN status and number of LN metastases; the primary endpoint was the BCR-free survival.

RESULTS

• The mean follow-up was 55.8 months. • Of all the patients, 305 (35%) were pNx and 567 (65.0%) were pN0/1. • Of the 567 patients submitted to PLND, the mean number of LNs obtained was 10.9, and 49 (8.6%) were pN1. • In the 402 patients at low risk of LNI, LN group was not a significant predictor of BCR at univariate analysis, while in the 470 patients at intermediate and high risk of LNI, patients with ≥ 10 LNs removed had a significantly lower BCR-free survival at univariate and multivariate analysis.

CONCLUSION

• In our study population, a more extensive PLND positively affects the BCR-free survival regardless of the nodal status in intermediate- and high-risk prostate cancer.