The role of lymphadenectomy in prostate cancer

Lymph node imaging in initial staging of prostate cancer: An overview and update

Accurate nodal staging at the time of diagnosis of prostate cancer is crucial in determining a treatment plan for the patient. Pelvic lymph node dissection is the most reliable method, but is less than perfect and has increased morbidity. Cross sectional imaging with computed tomography (CT) and magnetic resonance imaging (MRI) are non-invasive tools that rely on morphologic characteristics such as shape and size of the lymph nodes. However, lymph nodes harboring metastatic disease may be normal sized and non-metastatic lymph nodes may be enlarged due to reactive hyperplasia. The optimal strategy for preoperative staging remains a topic of ongoing research. Advanced imaging techniques to assess lymph nodes in the setting of prostate cancer utilizing novel MRI contrast agents as well as positron emission tomography (PET) tracers have been developed and continue to be studied. Magnetic resonance lymphography utilizing ultra-small super paramagnetic iron oxide has shown promising results in detection of metastatic lymph nodes. Combining MRL with diffusion-weighted imaging may also improve accuracy. Considerable efforts are being made to develop effective PET radiotracers that are performed using hybrid-imaging systems that combine PET with CT or MRI. PET tracers that will be reviewed in this article include [¹⁸F]fluoro-D-glucose, sodium [¹⁸F]fluoride, [¹⁸F]choline, [¹¹C]choline, prostate specific membrane antigen binding ligands, [¹¹C]acetate, [¹⁸F]fluciclovine, gastrin releasing peptide receptor ligands, and androgen binding receptors. This article will review these advanced imaging modalities and ability to detect prostate cancer metastasis to lymph nodes. While more research is needed, these novel techniques to image lymph nodes in the setting of prostate cancer show a promising future in improving initial lymph node staging.

Determination of adequate pelvic lymph node dissection range for Japanese males undergoing radical prostatectomy

The present study aimed to determine the adequate pelvic lymph node dissection (PLND) range for Japanese males undergoing radical prostatectomy. A total of 467 Japanese patients who underwent antegrade radical prostatectomy at the National Kyushu Cancer Center (Fukuoka, Japan) were retrospectively reviewed. The patients were divided into two groups according to the PLND extent: The standard (obturator + internal iliac nodes) group and the expanded (standard + additional nodes) group, which accounted for 64.5% (301/467) and 35.5% (166/467) of the patients, respectively. No differences were observed in the preoperative and postoperative characteristics of the two groups. In addition, there was no difference in PSA recurrence between the two groups. There were no differences between the standard and expanded groups in the low-, intermediate- and high-risk groups (P=0.1456, P=0.1581, P=0.2125, respectively). The median number of lymph node dissection was 13 and 19, in the standard and expanded groups respectively (P<0.0001). However, regarding the number of lymph node metastases and the rate of patients with lymph node metastasis, no significant difference was observed between the standard and expanded groups (P=0.4219 and P=0.4257, respectively). According to multivariate analysis, a significant difference in the presence of lymph node metastasis (hazard ratio 3.547; P=0.0247), but not in the PLND extent, was detected in patients with prostate specific antigen failure (P=0.0655). When expanding the dissection extent, the number of dissected lymph nodes increases, but is not associated with the number or rate of positive lymph nodes. Thus, the current dissection range is considered to be appropriate for Japanese men undergoing radical prostatectomy.

Prostate cancer: To scan or not to scan for lymph node involvement?

OBJECTIVE

When diagnosing lymph node involvement in prostate cancer (PC), the available imaging techniques are considered to be of doubtful value but are still in common use in many institutions because of a lack of better alternatives. To help us choose between methods while we wait for improvements in technologies, we evaluated the performance of ultrasonography (US), CT and MRI.

MATERIAL AND METHODS

We reviewed the records of all PC patients who were potential candidates for a surgical staging procedure prior to treatment with intent to cure at Skejby Sygehus, Denmark between 1996 and 2004. In total, 227 patients met our inclusion criteria and 149 were examined with US, 80 with MRI and 71 with CT. The performance of the three modalities was analysed.

RESULTS

A total of 50 patients (22%) had lymph node metastases (pN1) and only 12 of these cases (24%) were detected by imaging. US identified all 12 pN1 patients, MRI five and CT did not identify any. Moreover, US missed 28 patients with pN1 metastases, MRI 18 and CT 13. Consequently, US, MRI and CT had sensitivities of 0.3, 0.22 and 0, respectively, while all three modalities had a specificity of 1. The 12 patients identified by imaging had clinically advanced and pathologically aggressive cancers.

CONCLUSIONS

Available imaging techniques showed moderate to very low sensitivity. US proved superior to MRI and CT, but should only be applied in high-risk patients. In particular, CT can be considered unsuitable for diagnosing pelvic lymph node metastases in PC.

Prostate cancer: detection of lymph node metastases outside the routine surgical area with ferumoxtran-10-enhanced MR imaging

PURPOSE

To prospectively evaluate the feasibility of magnetic resonance (MR) imaging with ferumoxtran-10 in patients with prostate cancer to depict lymph node metastases outside the routine pelvic lymph node dissection (PLND) area.

MATERIALS AND METHODS

The study was approved by the institutional review boards at all four hospitals; patients provided written informed consent. Two hundred ninety-six consecutive men (mean age, 67 years; range, 47-83 years) with prostate cancer and an intermediate-to-high risk for nodal metastases (prostate-specific antigen level >10 ng/mL, Gleason score >6, or stage T3 disease) were enrolled. MR lymphography of the pelvis was performed 24 hours after intravenous drip infusion of ferumoxtran-10. Positive nodes at MR lymphography were indicated to be inside or outside the routine dissection area (RDA). On the basis of MR lymphography computed tomographic (CT)-guided biopsy, routine PLND, or MR imaging-guided minimal extended PLND was performed.

RESULTS

MR lymphography findings were positive in 58 patients. Of these, 44 had histopathologic confirmation of lymph node metastases. In 18 of 44 patients (41%), MR lymphography findings showed nodes exclusively outside the RDA, which were confirmed with MR lymphography-guided extended PLND (n = 13) and CT-guided biopsy (n = 5). In another 18 patients (41%), positive nodes were located both inside and outside the RDA at MR lymphography. In these 18 patients, routine PLND was used to confirm the nodes inside the RDA (n = 11); CT-guided biopsy was used to confirm nodes outside the RDA (n = 7). In the remaining eight patients, MR lymphography findings showed only nodes inside the RDA, which was confirmed with PLND (n = 5) and CT-guided biopsy (n = 3). In 14 of the 58 patients (24%), there was no histologic confirmation.

CONCLUSION

In 41% of patients with prostate cancer, nodal metastases outside the area of routine PLND were detected by using MR imaging with ferumoxtran-10.

Survival in surgically treated, nodal positive prostate cancer patients is predicted by histopathological characteristics of the primary tumor and its lymph node metastases

BACKGROUND

Histopathological risk factors for survival stratification of surgically treated nodal positive prostate cancer patients are poorly defined as reflected by only one category for nodal metastases.

METHODS

We evaluated biochemical recurrence-free survival (RFS), disease-specific survival (DSS), and overall survival (OS) in 102 nodal positive, hormone treatment-naïve prostate cancer patients (median age: 65 years, range: 45-75 years; median follow-up 7.7 years, range: 1.0-15.9 years) who underwent radical prostatectomy and standardized extended lymphadenectomy.

RESULTS

A significant stratification was possible, with the Gleason score of the primary and virtually all nodal parameters favoring patients with better differentiated primaries and metastases, lower nodal tumor burden, and without extranodal extension of metastases. In multivariate analyses, diameter of the largest metastasis (< or =10 mm vs. >10 mm) was the strongest independent predictor for RFS (P < 0.001), DSS (P < 0.001), and OS (P < 0.001) with a more than quadrupled relative risk of cancer related deaths for patients with larger metastases (Hazard ratio: 4.2, Confidence interval: 2.0-8.9; 5-year RFS/DSS/OS: 18%/57%/54%). The highest 5-year survival rates were seen in patients with micrometastases only (RFS/DSS/OS: 47%/94%/94%).

CONCLUSION

The TNM classification's current allocation of only one category for nodal metastases in prostate cancers is unsatisfactory since subgroups with significantly different prognoses can be identified. The diameter of the patient's largest metastasis (< or =10 mm vs. >10 mm) should be used for substaging because of its independent prognostic value. The substage "micrometastasis only" is also useful in nodal positive prostate cancer since it designates the subgroup with the most favorable outcome.

Prognostic factors in lymph node metastases of prostatic cancer patients: the size of the metastases but not extranodal extension independently predicts survival

AIMS

To analyse tumour characteristics and the prognostic significance of prostatic cancers with extranodal extension of lymph node metastases (ENE) in 102 node-positive, hormone treatment-naive patients undergoing radical prostatectomy and extended lymphadenectomy.

METHODS AND RESULTS

The median number of nodes examined per patient was 21 (range 9-68), and the median follow-up time was 92 months (range 12-191). ENE was observed in 71 patients (70%). They had significantly more, larger and less differentiated nodal metastases, paralleled by significantly larger primary tumours at more advanced stages and with higher Gleason scores than patients without ENE. ENE defined a subgroup with significantly decreased biochemical recurrence-free (P = 0.038) and overall survival (P = 0.037). In multivariate analyses the diameter of the largest metastasis and Gleason score of the primary tumour were independent predictors of survival.

CONCLUSIONS

ENE in prostatic cancer is an indicator lesion for advanced/aggressive tumours with poor outcome. However, the strong correlation with larger metastases suggests that ENE may result from their size, which was the only independent risk factor in the metastasizing component. Consequently, histopathological reports should specify the true indicator of poor survival in the lymphadenectomy specimens, which is the size of the largest metastasis in each patient.

Limited Pelvic Lymph Node Dissection at the Time of Radical Prostatectomy Does Not Affect 5-Year Failure Rates for Low, Intermediate and High Risk Prostate Cancer: Results From CaPSURE™

PURPOSE

Limited bilateral pelvic lymph node dissection performed at radical prostatectomy provides staging information that is used to guide further disease management. Given the effects of widespread prostate specific antigen testing and stage migration, most procedures in the United States are performed for low risk disease, which has a low probability (less than 1%) of lymph node metastasis. We compared 5-year treatment failure rates in patients with low, intermediate and high risk disease who underwent radical prostatectomy with or without pelvic lymph node dissection.

MATERIALS AND METHODS

We compared treatment failure rates for radical prostatectomy in 4,693 patients enrolled in the CaPSURE database who underwent radical prostatectomy with or without limited pelvic lymph node dissection. Secondary analysis was performed as a function of pelvic lymph node dissection and risk group based on pretreatment stage, grade and prostate specific antigen. Treatment failure rates were estimated by Kaplan-Meier analysis.

RESULTS

The 5-year failure-free survival rate was 70% in the no pelvic lymph node dissection group and 74% in the limited pelvic lymph node dissection group (p = 0.11), while the rates in the low, intermediate and high risk groups were 81% and 82% (p = 0.83), 71% and 63% (p = 0.21), and 42% and 48% (p = 0.45) in the no vs limited pelvic lymph node dissection groups, respectively. Multivariate analysis demonstrated that pelvic lymph node dissection status was not a predictor of treatment failure (p = 0.93).

CONCLUSIONS

This study demonstrates in a large cohort of patients that limited pelvic lymph node dissection at radical prostatectomy has no effect on treatment failure rates at 5 years in those at low, intermediate and high risk.

Laparoscopic Peritoneal Drainage of Symptomatic Lymphoceles after Pelvic Lymph Node Dissection Using Methylene Blue Instillation

BACKGROUND

Lymphoceles are frequent complications of pelvic lymph node dissection. While small lymphoceles often remain undetected, larger ones can cause complications and require further treatment, e.g. percutaneous tube drainage alone or in combination with sclerotherapy. However, recurrence rates are considerable, and long-lasting drainage may lead to infection, prolonged hospitalization, and as a consequence, increased overall costs. We report the results of a simplified laparoscopic approach to drain lymphoceles after radical prostatectomy plus pelvic lymphadenectomy using methylene blue instillation.

METHODS

13 patients with large symptomatic pelvic/retroperitoneal lymphoceles refractory to percutaneous tube drainage and doxycycline sclerotherapy received a laparoscopic transperitoneal marsupialization following instillation of a sterile diluted methylene blue solution into the drained cavity to refill and mark the lymphocele.

RESULTS

All lymphoceles were sterile and ranged in size from 7 x 6 x 4 to 15 x 12 x 6 cm. Clinical symptoms included lower abdominal swelling, tenderness in the iliac fossa, ipsilateral lymphedema, deep venous thrombosis, wound fistula, and hydronephrosis due to ureteral obstruction. After methylene blue instillation, the lymphoceles were easily identified and opened. Median total operative time was 50 (range 25-70) min; blood loss was negligible. There was one complication in the form of a metachronous infection in the operating field and no relapses. Patients were discharged 1-5 (median 3) days after the surgical procedure.

CONCLUSIONS

Laparoscopic peritoneal drainage requires greater operative skill than percutaneous approaches. However, the instillation of a methylene blue solution simplifies this procedure as the extent and location of the lymphoceles can be precisely identified during laparoscopy. We recommend early application of laparoscopic peritoneal drainage following methylene blue instillation for patients with sterile lymphoceles after pelvic lymph node dissection in whom temporary percutaneous drainage and sclerotherapy failed to resolve the lymph fluid collection.

Use of the gamma probe in sentinel lymph node biopsy in patients with prostate cancer

OBJECTIVE

To describe the reproducibility of the sentinel lymph node technique in patients with prostate cancer and verify if there is improved accuracy over modified lymphadenectomy.

MATERIAL AND METHODS

Twenty-three patients with biopsy proven prostate cancer were enrolled in this study. Lymphoscintigraphy was performed after the transrectal administration of Tc sulfur colloid guided by ultrasound, with one injection in each prostate lobe. Images were obtained 15 and 180 min after injection. Sentinel lymph node was harvested during surgery using a gamma probe, followed by extended lymphadenectomy.

RESULTS

The mean age of the patients in this study was 66 years. An average of 3.36 sentinel lymph nodes was found for each patient. Radioactive lymph nodes were identified by the gamma probe in 21 out of 23 patients. In one of the patients there was no radiopharmaceutical migration from the injection site and in another the sentinel lymph node was visualized by lymphoscintigraphy but was not found during surgery. Three patients had lymph node metastasis; in one of these patients the sentinel lymph node was the only positive node and was found outside the modified lymphadenectomy region (obturator fossa and the external iliac).

CONCLUSION

Sentinel lymph node biopsy in prostate cancer adds important information to the staging of patients, not always attained through the lymphadenectomy restricted to the obturator fossa and external iliac. Such information is essential for the choice of the best treatment to be applied.