Individualized image-based lymph node irradiation for prostate cancer

Patterns of Lymph Node Failure in Patients With Recurrent Prostate Cancer Postradical Prostatectomy and Implications for Salvage Therapies

PURPOSE

There is increasing use of radical prostatectomy to treat patients with high-risk prostate cancer. This has contributed toward a pathologic stage migration, and a greater number of patients are subsequently being diagnosed with biochemical failure. There is increasing use of advanced imaging techniques in the setting of biochemical failure, including positron emission tomography-computed tomography (PET-CT).

METHODS AND MATERIALS

This critical literature review highlights the evidence for PET-CT in postprostatectomy biochemical failure and identifies sites of pelvic lymph node relapse in the setting of biochemical failure and the potential implications that the locations of these relapses may have for salvage therapies. Potential future directions are then considered.

RESULTS

The optimal PET-CT tracer remains uncertain but there is increasing use of prostate-specific membrane antigen PET-CT for investigating sites of nodal metastasis at low prostate-specific antigen levels, and this is leading to a blurring of the biochemical and radiologic recurrence phases. The optimal therapeutic approach remains undefined, with current trials investigating postoperative radiation therapy to the whole pelvis in addition to the prostatic fossa, the use of PET-CT in the setting of biochemical recurrence to guide delivery of salvage radiation therapy, and, for patients with node-only relapsed prostate cancer, the addition of whole pelvis radiation therapy to metastasis-directed therapies such as stereotactic ablative radiotherapy.

CONCLUSIONS

The most appropriate target volume for salvage radiation therapy remains uncertain, and the findings of studies using PET-CT to map nodal recurrences suggest that there could be a role for extending whole pelvis radiation therapy volumes to increase coverage of superior nodal regions. The emerging fields of radiomics and radiogenomics could provide important prognostic information and aid decision making for patients with relapsed prostate cancer.

PET and PET/CT with radiolabeled choline in prostate cancer: a critical reappraisal of 20 years of clinical studies

We here aim to provide a comprehensive and critical review of the literature concerning the clinical applications of positron emission tomography/computed tomography (PET/CT) with radiolabeled choline in patients with prostate cancer (PCa). We will initially briefly summarize the historical context that brought to the synthesis of [¹¹C]choline, which occurred exactly 20 years ago. We have arbitrarily grouped the clinical studies in three different periods, according to the year in which they were published and according to their relation with their applications in urology, radiotherapy and oncology. Studies at initial staging and, more extensively, studies in patients with biochemical failure, as well as factors predicting positive PET/CT will be reviewed. The capability of PET/CT with radiolabeled choline to provide prognostic information on PCa-specific survival will also be examined. The last sections will be devoted to the use of radiolabeled choline for monitoring the response to androgen deprivation therapy, radiotherapy, and chemotherapy. The accuracy and the limits of the technique will be discussed according to the information available from standard validation processes, including biopsy or histology. The clinical impact of the technique will be discussed on the basis of changes induced in the management of patients and in the evaluation of the response to therapy. Current indications to PET/CT, as officially endorsed by guidelines, or as routinely performed in the clinical practice will be illustrated. Emphasis will be made on methodological factors that might have influenced the results of the studies or their interpretation. Finally, we will briefly highlight the potential role of positron emission tomography/magnetic resonance and of new radiotracers for PCa imaging.

Whole body MRI (WB-MRI) assessment of metastatic spread in prostate cancer: Therapeutic perspectives on targeted management of oligometastatic disease

OBJECTIVES

To determine the proportion of prostate cancer (PCa) patients with oligometastatic disease (≤3 synchronous lesions) using whole body magnetic resonance imaging with diffusion-weighted imaging (WB-MRI/DWI). To determine the proportion of patients with nodal disease confined within currently accepted target areas for extended lymph node dissection (eLND) and pelvic external beam radiation therapy (EBRT).

SUBJECTS AND METHODS

Two radiologists reviewed WB-MRI/DWI studies in 96 consecutive newly diagnosed metastatic PCa patients; 46 patients with newly diagnosed castration naive PCa (mHNPC) and 50 patients with first appearance of metastasis during monitoring for non-metastatic castration resistant PCa (M0 to mCRPC). The distribution of metastatic deposits was assessed and the proportions of patients with oligometastatic disease and with LN metastases located within eLND and EBRT targets were determined.

RESULTS

Twenty-eight percent of mHNPC and 50% of mCPRC entered the metastatic disease with ≤3 sites. Bone metastases (BM) were identified in 68.8% patients; 71.7% of mHNPC and 66% mCRPC patients. Most commonly involved areas were iliac bones and lumbar spine. Enlarged lymph nodes (LN) were detected in 68.7% of patients; 69.6% of mHNPC and 68.0% of mCRPC. Most commonly involved areas were para-aortic, inter-aortico-cava, and external iliac areas. BM and LN were detected concomitantly in 41% of mHNPC and 34% of mCRPC. Visceral metastases were detected in 6.7%. Metastatic disease was confined to LN located within the accepted boundaries of eLND or pelvic EBRT target areas in only ≤25% and ≤30% of patients, respectively.

CONCLUSIONS

Non-invasive mapping of metastatic landing sites in PCa using WB-MRI/DWI shows that 28% of the mHNPC patients, and 52% of the mCRPC can be classified as oligometastatic, thus challenging the concept of metastatic targeted therapy. More than two thirds of metastatic patients have LN located outside the usually recommended targets of eLND and pelvic EBRT. Prophylactic or salvage treatments of these sole areas in patients with high-risk prostate cancer may not prevent the emergence of subsequent metastases. Prostate 76:1024-1033, 2016. © 2016 Wiley Periodicals, Inc.

Distribution of prostate nodes: a PET/CT-derived anatomic atlas of prostate cancer patients before and after surgical treatment

BACKGROUND

In order to define adequate radiation portals in nodal positive prostate cancer a detailed knowledge of the anatomic lymph-node distribution is mandatory. We therefore systematically analyzed the localization of Choline PET/CT positive lymph nodes and compared it to the RTOG recommendation of pelvic CTV, as well as to previous work, the SPECT sentinel lymph node atlas.

METHODS

Thirty-two patients being mostly high risk patients with a PSA of 12.5 ng/ml (median) received PET/CT before any treatment. Eighty-seven patients received PET/CT for staging due to biochemical failure with a median PSA of 3.12 ng/ml. Each single PET-positive lymph node was manually contoured in a "virtual" patient dataset to achieve a 3-D visualization, resulting in an atlas of the cumulative PET positive lymph node distribution. Further the PET-positive lymph node location in each patient was assessed with regard to the existence of a potential geographic miss (i.e. PET-positive lymph nodes that would not have been treated adequately by the RTOG consensus on CTV definition of pelvic lymph nodes).

RESULTS

Seventy-eight and 209 PET positive lymph nodes were detected in patients with no prior treatment and in postoperative patients, respectively. The most common sites of PET positive lymph nodes in patients with no prior treatment were external iliac (32.1 %), followed by common iliac (23.1 %) and para-aortic (19.2 %). In postoperative patients the most common sites of PET positive lymph nodes were common iliac (24.9 %), followed by external iliac (23.0 %) and para-aortic (20.1 %). In patients with no prior treatment there were 34 (43.6 %) and in postoperative patients there were 77 (36.8 %) of all detected lymph nodes that would not have been treated adequately using the RTOG CTV. We compared the distribution of lymph nodes gained by Choline PET/CT to the preexisting SPECT sentinel lymph node atlas and saw an overall good congruence.

CONCLUSIONS

Choline PET/CT and SPECT sentinel lymph node atlas are comparable to each other. More than one-third of the PET positive lymph nodes in patients with no prior treatment and in postoperative patients would not have been treated adequately using the RTOG CTV. To reduce geographical miss, image based definition of an individual target volume is necessary.

The value of magnetic resonance imaging for radiotherapy planning

The success of highly conformal radiotherapy techniques in the sparing of normal tissues or in dose escalation, or both, relies heavily on excellent imaging. Because of its superior soft tissue contrast, magnetic resonance imaging is increasingly being used in radiotherapy treatment planning. This review discusses the current clinical evidence to support the pivotal role of magnetic resonance imaging in radiation oncology.

Lymphotropic nanoparticle-enhanced MRI in prostate cancer: value and therapeutic potential

Nodal staging in prostate cancer is suboptimal both with respect to current imaging modalities and pelvic lymph node dissection, and thus other techniques are being explored. Lymphotropic nanoparticle-enhanced MRI, also called magnetic resonance lymphography (MRL), is a technique that has shown high sensitivity (65-92 %) and excellent specificity (93-98 %) in detecting prostate cancer lymph node metastases. This technique aids in the detection of metastases in non-enlarged small nodes. MRL has been useful in determining the location and pathways of spread in nodal chains. Knowledge of the location of lymph node involvement is important for decisions regarding appropriate therapeutic options, such as image-guided therapy.. A geographic miss in radiotherapy can be avoided with the use of MRL-guided focal therapy. This paper provides an overview of current literature, lessons learned, and new therapeutic options with nanoparticle-enhanced MRI.