Can pelvic node dissection at radical prostatectomy influence the nodal recurrence at salvage lymphadenectomy for prostate cancer?

Validating Modern NRG Oncology Pelvic Nodal and Groupe Francophone de Radiothérapie Urologique Prostate Bed Contouring Guidelines for Post-Prostatectomy Salvage Radiation: A Secondary Analysis of the LOCATE Trial

PURPOSE

We used the patterns of recurrence on ¹⁸F-fluciclovine positron emission tomography (PET)-computed tomography (CT) in patients enrolled in the LOCATE trial after prostatectomy to evaluate how well the most recent NRG Oncology and Groupe Francophone de Radiothérapie Urologique (GFRU) contouring recommendations encompassed all sites of recurrence in the prostate fossa and pelvic nodes in comparison to former Radiation Therapy Oncology Group (RTOG) recommendations.

METHODS AND MATERIALS

Patients with biochemically recurrent prostate cancer after radical prostatectomy with a positive finding within the prostate fossa or pelvic nodes on ¹⁸F-fluciclovine PET/CTs were identified from the LOCATE patient population. Areas of gross disease were delineated. Prostate fossa contours were delineated using both the 2010 RTOG consensus guidelines and the recently published 2020 GFRU consensus guidelines. Pelvic nodes were contoured with both the 2009 RTOG consensus guidelines and the 2020 NRG consensus guidelines. The performance of the contouring guidelines was assessed by determining what proportion of gross recurrent lesions were encompassed completely or marginally.

RESULTS

Of the 213 patients within the LOCATE trial, 45 patients were eligible for analysis with positive ¹⁸F-fluciclovine PET findings. Of the 30 total prostate fossa recurrences, the 2010 RTOG contour covered 20 (67%) and missed or marginally covered 10 (33%). The 2020 GFRU contour covered 27 recurrences (90%), and missed or marginally covered 3 (10%). Of the 43 total nodal recurrences, the 2009 RTOG pelvic nodal contour covered 29 nodes (67%), and missed or marginally covered 14 (32%). The 2020 NRG pelvic nodal contour covered 43 nodes (100%), with no misses or marginal coverage.

CONCLUSIONS

This secondary analysis of the LOCATE trial exemplifies the improved coverage of the latest prostate fossa contouring recommendations from the GFRU. Similarly, it also validates the updated 2020 NRG pelvic nodal contouring guidelines by demonstrating improved coverage of recurrent disease in this patient population.

PSMA-PET/CT-based Lymph Node Atlas for Prostate Cancer Patients Recurring After Primary Treatment: Clinical Implications for Salvage Radiation Therapy

BACKGROUND

Many patients experience recurrence of prostate cancer after radical prostatectomy.

OBJECTIVE

The aim of this study was to visually analyze typical patterns of lymph node (LN) involvement for prostate cancer (PC) patients with biochemical recurrence after radical prostatectomy and lymphadenectomy by creating a color-coded heat map using gallium-68 prostate-specific membrane antigen positron emission tomography (⁶⁸Ga-PSMA-PET) imaging. Further, we evaluated which LNs were covered by the Radiation Therapy Oncology Group (RTOG) clinical target volume (CTV) contouring guidelines.

DESIGN, SETTING, AND PARTICIPANTS

A total of 1653 ⁶⁸Ga-PSMA-PET/computed tomography (CT) datasets were screened retrospectively. After meeting the eligibility criteria, 233 patients with 799 LN metastases were included in our study.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

We created a comprehensive three-dimensional color-coded LN atlas. Further, the coverage of LN metastases by RTOG CTV was assessed and stratification for risk factors was performed.

RESULTS AND LIMITATIONS

In the overall, mainly high risk, collective, complete coverage by the standard RTOG CTV was accomplished in 31.0% of all LN metastases. The vast majority of uncovered LNs are situated in the para-aortal, pararectal, paravesical, preacetabular, presacral, and inguinal regions. Concerning examined stratification factors, prostate-specific antigen (PSA) levels at the time of PET/CT imaging had the highest predictive value for extrapelvic metastatic LN spread. Every increase of 1 ng/mL in PSA raises the risk of metastases outside the CTV by a factor of 1.43.

CONCLUSIONS

We developed the first LN atlas for patients with recurrent PC using a heat map technique, in order to illustrate hot spots of LN recurrence. The vast majority of detected LNs are not covered by a standard CTV as recommended by the RTOG. Application of the standard RTOG CTV for pelvic irradiation in the salvage setting for high-risk PC patients seems to be inappropriate.

PATIENT SUMMARY

We visualized typical lymph node recurrence sites for patients after prostate cancer surgery.

Role of Para-aortic Radiotherapy in the Management of Prostate Cancer

Recent studies assessing the patterns of failure following locoregional definitive therapy suggest that recurrences do happen in the adjacent most proximal drainage sites, not infrequently occurring within the common iliac and para-aortic regions. This pattern of recurrence and identification at initial presentation is being increasingly recognised using novel imaging techniques and there is limited evidence on how to manage these patients. We are awaiting definitive evidence regarding the clinical benefit of whole pelvic radiotherapy, and currently there is no consensus as to the optimal superior border. There is some acknowledgement that the superior border should encompass the common iliac nodal region. However, whether it should be extended even more proximally is currently unknown. Prospective randomised trials are required to determine if there is a role for extending the radiotherapy field in patients with or at high risk of para-aortic metastases.

Salvage lymphadenectomy in recurrent prostate cancer: is there evidence of real benefit?

PURPOSE

Nodal recurrent prostate cancer (PCa) after primary radical treatment represents a heterogeneous entity with many treatment options. In some cases, surgical removal of metastatic nodes seems to improve cancer control and delay systemic treatments. The objectives of this study were to analyze the available literature on salvage lymphadenectomy for the treatment of nodal recurrent PCa and to elucidate the real oncological benefit deriving from this procedure.

METHODS

A PubMed search was performed using the following terms: prostate cancer, metastatic, oligometastatic, salvage lymphadenectomy, salvage lymph node dissection, salvage lymph node excision, and cytoreductive surgery. We included in the study all papers on salvage lymphadenectomy in nodal recurrent PCa, with no temporal limits. In addition, several papers addressing cytoreductive surgery and the biology of oligometastatic disease, published in different medical and basic research journals, were included.

RESULTS

Salvage lymphadenectomy is still characterized by a lack of standardization in patient selection and surgical template. Its primary objectives are to prolong progression-free survival and to delay the need for systemic therapy. The improvements in preoperative imaging techniques in conjunction with the wide use of minimally invasive surgery have generated growing interest in this procedure.

CONCLUSION

Salvage lymphadenectomy is a promising treatment approach; however, its real oncological benefit is still far from proven. Prospective randomized trials need to be designed to improve understanding of this issue.

Oligometastatic prostate cancer and salvage lymph node dissection: systematic review

INTRODUCTION

We provide a comprehensive description of the physio-pathological theories behind oligometastatic prostate cancer (PCa) and analyze modern imaging techniques, presenting a systematic review of the available evidences regarding salvage lymph node dissection (sLND).

EVIDENCE ACQUISITION

A systematic review was attempted. The PubMed/Medline database was searched for "salvage" AND ("lymph node dissection" OR "lymphadenectomy") AND "prostate" AND "cancer." Only English publications were targeted. Relevant original articles addressing the role of sLND in PCa were selected.

EVIDENCE SYNTHESIS

Biochemical response (BR) was reported in 10-79.5% of the cases overall. These results were not durable and biochemical recurrence occurred in 54.5-93.8% of the cases, within 5 years. Furthermore, 50-80% of patients received some kind of adjuvant treatment right after sLND, regardless post-operative prostate-specific antigen levels. Surgery-related morbidity was low, with a 0-27% incidence of Clavien-Dindo III complications. No sLND-related deaths were observed.

CONCLUSIONS

sLND is not associated with a durable response over time but may postpone HT and its related complications, in selected patients. Although a limited morbidity was reported, sLND remains technically demanding and a careful selection of patients is advisable.