Molecular imaging for prostate cancer: Performance analysis of 68Ga-PSMA PET/CT versus choline PET/CT

Effectiveness of 11C-choline PET/CT in prostate cancer surveillance

AIM

Our aim was to analyse the performance of [¹¹C]choline PET/CT in prostate cancer (PCa) surveillance, especially in patients with prostate specific antigen (PSA) < 1 ng/mL.

MATERIAL AND METHODS

Three hundred and twenty-nine [¹¹C]choline PET/CT examinations from 191 patients (68.2 ± 7.2 years) submitted for PCa surveillance or biochemical recurrence were retrospectively evaluated. PSA at study was 13.0 ± 84.2 ng/mL. Main initial treatment was radical prostatectomy (RP) in 81 patients, and other treatments (radiotherapy, chemotherapy, hormonotherapy) in 110. PET/CT was acquired 20' after injection of 555-740 MBq of [¹¹C]choline. Minimum follow-up was 12 months.

RESULTS

Two hundred and nineteen (66.6%) out of the 329 PET/CT examinations were positive. The percentage of positive examinations was significantly higher in patients with other initial treatment than RP compared to patients with RP (85.6% vs. 43.6%, respectively). One hundred and thirty PET/CT (59.4%) showed local recurrence, 48 (21.9%) distant recurrence, and 41 (18.7%) local plus distant recurrence. Initial therapeutic approach was changed in 139 cases (63.5%). In the subgroup of 81 [¹¹C]choline PET/CT scans performed with PSA < 1 ng/mL, 23 (28.4%) showed a positive result. Initial therapeutic approach was changed in 9 (11.1%). Three (4.8%) out of 63 patients died as per PCa.

CONCLUSION

[¹¹C]choline PET/CT demonstrated its effectiveness in PCa surveillance and restaging, even in patients with serum PSA < 1 ng/mL. The diagnostic performance was different depending on the initial treatment, been higher in patients with non-surgical treatment.

Advances in prostate-specific membrane antigen PET of prostate cancer

PURPOSE OF REVIEW

In recent years, a large number of reports have been published on prostate-specific membrane antigen (PSMA)/PET in prostate cancer (PCa). This review highlights advances in PSMA PET in PCa during the past year.

RECENT FINDINGS

PSMA PET/computed tomography (CT) is useful in detection of biochemical recurrence, especially at low prostate-specific antigen (PSA) values. The detection rate of PSMA PET is influenced by PSA level. For primary PCa, PSMA PET/CT shows promise for tumour localization in the prostate, especially in combination with multiparametric MRI (mpMRI). For primary staging, PSMA PET/CT can be used in intermediate and high-risk PCa. Intraoperative PSMA radioligand guidance seems promising for detection of malignant lymph nodes. While the use of PSMA PET/MRI in primary localized disease is limited to high and intermediate-risk patients and localized staging, in the recurrence setting, PET/MRI can be particularly helpful when the lesions are subtle. PSMA PET/CT is superior to choline PET/CT and other conventional imaging modalities.

SUMMARY

Molecular imaging with PSMA PET continues to pave the way for personalized medicine in PCa.However, large prospective clinical studies are still needed to fully evaluate the role of PSMA PET/CT and PET/MRI in the clinical workflow of PCa.

Effect of positive carbon-11-choline PET/CT results in the therapeutic management of prostate cancer biochemical relapse

OBJECTIVE

Carbon-11-(C)-choline PET/computed tomography (CT) has shown good results in re-staging of prostate cancer (PCa) with raised serum levels of prostate-specific antigen. Our aim was to evaluate the effect of positive C-choline PET/CT results in the therapeutic management of patients with PCa with biochemical relapse (BR) after curative intention treatment.

PATIENTS AND METHODS

A total of 112 patients with PCa BR and positive C-choline PET/CT were retrospectively evaluated. PET/CT was acquired 20 min after intravenous administration of 555-740 MBq of C-choline. The therapeutic management after C-choline PET/CT was obtained from the clinical records. The minimum follow-up time was 18 months.

RESULTS

In 80 (71.4%) of 112 patients, C-choline PET/CT showed local recurrence of PCa; in 17 (15.2%) patients, distant recurrence; and in 15 (13.4%) patients, local plus distant recurrence. A second malignancy was detected in five (4.5%) patients. The planned therapeutic management was changed as per positive C-choline PET/CT result in 74 (66.1%) patients and were treated as follows: 31 (27.7%) patients with HT, combined with other treatments in eight (7.1%), 17 (15.2%) with BT, 13 (11.6%) with external beam radiotherapy, one (0.9%) with RP, and four (3.6%) with chemotherapy. Treatment approach was not modified in 37 (33%) patients. No data was available from one (0.9%) patient.

CONCLUSION

Positive C-choline PET/CT result had an important effect in the therapeutic management of patients with PCa and BR, leading to a change in the planned approach in two (66.1%) out of three patients. In addition, in 4.5% of the patients, the C-choline PET/CT allowed the detection of a second malignancy.

68Ga-PSMA PET/CT and PET/MRI in high-risk prostate cancer patients

Treatment of high-risk prostate cancer (HRPCa) is challenging. Local staging and metastatic evaluation are important for the patient management. Recently, prostate-specific membrane antigen (PSMA)-based imaging modalities such as PSMA PET/CT and PET/MRI have received significant attention for detection of recurrent prostate cancer sites with elevated prostate-specific antigen levels, after therapy. Current evidence suggests that these imaging modalities may also have a role for the management of patients with HRPCa. In this review, we discuss PSMA-based imaging modalities in the management of patients with HRPCa.

Radiation therapy for oligorecurrence in prostate cancer. Preliminary results of our centre

INTRODUCTION AND OBJECTIVE

There is growing interest in the use of more aggressive therapeutic modalities for treating metastatic prostate cancer. In this study, we examine the use of stereotactic body radiation therapy (SBRT) for patients with oligorecurrent prostate cancer. We analysed the biochemical response and toxicity of patients who underwent this therapy at our centre.

MATERIAL AND METHOD

We selected patients who experienced oligorecurrence between January 2015 to December 2016 and were administered SBRT. The association of androgen deprivation (AD) was left in each case to the decision of the tumour committee. We describe the clinical situation at diagnosis of oligorecurrence, the treatment administered and the biochemical response. We considered a biochemical response to be a 50% reduction in the absolute prostate-specific antigen (PSA) readings.

RESULTS

SBRT was administered to 11 patients with bone (82%) and/or lymph node oligometastasis (18%). The treatment regimen for bone oligometastasis was 27Gy divided into 3 sessions, while the treatment for lymph node oligometastasis reached 70Gy. Seven patients had no treatment at the time of diagnosis, 2 were in the castration-resistant phase, 1 patient was in the off phase of intermittent AD, and 1 patient had adjuvant AD for pN1. Seven patients presented a biochemical response with a PSA reduction of 75-100%. The response was not assessable in 4 patients due to the continuing adjuvant AD. With a mean follow-up of 10.5 months, only 2 patients had progressed. Grade 1 gastrointestinal toxicity was detected in only 1 patient.

CONCLUSION

Our data suggest that the use of SBRT in carefully selected patients with metastatic oligorecurrence of prostate cancer can achieve biochemical response and potentially delay progression and the use of systemic treatments.

Patterns of failure after radical prostatectomy in prostate cancer - implications for radiation therapy planning after 68Ga-PSMA-PET imaging

BACKGROUND

Salvage radiotherapy (SRT) after radical prostatectomy (RPE) and lymphadenectomy (LAE) is the appropriate radiotherapy option for patients with persistent/ recurrent prostate cancer (PC). ⁶⁸Ga-PSMA-PET imaging has been shown to accurately detect PC lesions in a primary setting as well as for local recurrence or for lymph node (LN) metastases.

OBJECTIVE

In this study we evaluated the patterns of recurrence after RPE in patients with PC, putting a highlight on the differentiation between sites that would have been covered by a standard radiation therapy (RT) field in consensus after the RTOG consensus and others that would have not.

METHODS AND MATERIALS

Thirty-one out of 83 patients (37%) with high-risk PC were the subject of our study. Information from ⁶⁸Ga-PSMA-PET imaging was used to individualize treatment plans to include suspicious lesions as well as possibly boost sites with tracer uptake in LN or the prostate bed. For evaluation, ⁶⁸Ga-PSMA-PET-positive LN were contoured in a patient dataset with a standard lymph drainage (RTOG consensus on CTV definition of pelvic lymph nodes) radiation field depicting color-coded nodes that would have been infield or outfield of that standard lymph drainage field and thereby visualizing typical patterns of failure of a "blind" radiation therapy after RPE and LAE.

RESULTS

Compared to negative conventional imaging (CT/MRI), lesions suspicious for PC were detected in 27/31 cases (87.1%) by ⁶⁸Ga-PSMA-PET imaging, which resulted in changes to the radiation concept. There were 16/31 patients (51.6%) that received a simultaneous integrated boost (SIB) to a subarea of the prostate bed (in only three cases this dose escalation would have been planned without the additional knowledge of ⁶⁸Ga-PSMA-PET imaging) and 18/31 (58.1%) to uncommon (namely presacral, paravesical, pararectal, preacetabular and obturatoric) LN sites. Furthermore, 14 patients (45.2%) had a changed TNM staging result by means of ⁶⁸Ga-PSMA-PET imaging.

CONCLUSION

Compared to conventional CT or MRI staging, ⁶⁸Ga-PSMA-PET imaging detects more PC lesions and, thus, significantly influences radiation planning in recurrent prostate cancer patients enabling individually tailored treatment.