Role of choline PET/CT in guiding target volume delineation for irradiation of prostate cancer

Positron emission tomography with computed tomography imaging (PET/CT) for the radiotherapy planning definition of the biological target volume: PART 2

AIM

Positron Emission Tomography with Computed Tomography (PET/CT) has been proven to be useful in the definition of Radiotherapy (RT) target volume. In this regard, the present expert review summarizes existing data for pancreas, prostate, gynecological and rectum/anal cancer.

METHODS

A comprehensive search of published original article was made, based on SCOPUS and PubMed database, selecting the paper that evaluated the role of PET/CT in the definition of RT volume.

RESULTS

FDG-PET has an important and promising role for pancreatic cancer. Choline PET/CT could be useful for identifying high-risk volumes for prostate cancer; while PSMA PET/CT is still under evaluation. FDG PET/CT in gynecological cancers has been shown to impact external-beam RT planning. The role of FDG-PET for Gross Tumor volume identification is crucial, representing a useful and powerful tool for anal and rectal cancer.

CONCLUSION

Taken together, molecular and functional imaging approaches offer a major step to individualize radiotherapeutic approach.

11C-choline PET/CT predicts survival in prostate cancer patients with PSA < 1 NG/ml

PURPOSE

The main drawback of ¹¹C-choline PET/CT for restaging prostate cancer (PCa) patients with biochemical failure is the relatively low positive detection rate for prostate specific antigen (PSA) < 1 ng/ml. This study assessed whether ¹¹C-choline PET/CT predicts survival in PCa patients with PSA < 1 ng/ml.

METHODS

This retrospective study included 210 PCa patients treated with radical prostatectomy who underwent ¹¹C-choline PET/CT from December 1, 2004 to July 31, 2007 due to biochemical failure. PCa-specific survival was estimated using Kaplan-Meier curves. Cox regression analysis was used to evaluate the association between clinicopathologic variables and PCa-specific survival. PCa-specific survival was computed as the interval from radical prostatectomy to PCa-specific death.

RESULTS

Median follow-up after radical prostatectomy was 6.9 years (95% confidence interval, CI, 2.0-14.5 years). ¹¹C-choline PET/CT was positive in 20.5% of patients. Median PCa-specific survival was 13.4 years (95% CI, 9.9-16.8 years) in patients with positive ¹¹C-choline PET/CT, and it was not achieved in patients with negative ¹¹C-choline PET/CT (log-rank, chi-square = 15.0, P < 0.001). Ten-year survival probabilities for patients with negative ¹¹C-choline PET/CT and for patients with positive ¹¹C-choline PET/CT were 86.0% (95% CI: 80.7%-91.3%) and 63.6% (95% CI: 54.5-72.7%). At multivariate analysis, only ¹¹C-choline PET/CT significantly predicted PCa-specific survival (hazard ratio = 2.54, 95% CI, 1.05-6.13, P = 0.038). Patients with pathological ¹¹C-choline uptake in the prostatic bed or in pelvic lymph nodes had longer PCa-specific survival in comparison to patients with pathological tracer uptake in the skeleton (log-rank: chi-square = 27.4, P < 0.001).

CONCLUSION

Despite the relatively low positive detection rate for PSA < 1 ng/ml, positive ¹¹C-choline PET/CT predicts PCa-specific survival in this low PSA range. As long as more sensitive radiotracers, such as ⁶⁸Ga-PSMA-11, do not become more widely available, these results might support a broader use of radiolabeled choline in restaging PCa for PSA < 1 ng/ml.

Role of 11C-choline PET/CT in radiation therapy planning of patients with prostate cancer

BACKGROUND

In the era of image-guided radiotherapy, PET has become an important tool for tumor delineation in several types of cancer. The aim of this study was to evaluate the effect of this imaging modality in treatment planning of a cohort of patients with prostate cancer eligible for radiotherapy.

METHODS

From September 2011 to January 2016, 135 consecutive patients (median age 69 years, range: 53-89) were referred to our department for radiation therapy with radical intent (n=28), for postoperative adjuvant (n=13) or salvage treatment (n=50), for re-irradiation (n=19), or for radiotherapy on oligometastases (n=25). Before planning the radiotherapy course, patients were submitted to carbon-11-choline PET (Cho-PET) to confirm the indication to radiotherapy and the irradiation volumes.

RESULTS

Among the 135 patients subjected to Cho-PET, the indication to radiotherapy was modified in 66 (48.8%) cases based on the Cho-PET result. In particular, Cho-PET helped to better define the radiotherapy programme in 12 out of 28 (42.8%) patients who were candidates for primary radiation therapy, 33 (52.4%) of 63 patients undergoing adjuvant/salvage radiotherapy, and 21 out of 44 (47.7%) patients with relapsed/metastatic disease. Overall biochemical response is documented by mean and median prostate specific antigen values, which changed from 15.29 to 4.00 ng/ml, respectively, before to mean 4.74 ng/ml and median 0.81 ng/ml after therapy (P=0.05).

CONCLUSION

In our series, Cho-PET had a significant effect on radiotherapy planning of patients affected by prostate cancer, determining a change in management in 48.8% of cases, considering all therapeutic indications.

The impact of [68Ga]PSMA I&T PET/CT on radiotherapy planning in patients with prostate cancer

PURPOSE

To determine the impact of Gallium-68-labled prostate-specific membrane antigen positron-emission tomography/computed tomography ([⁶⁸Ga]PSMA PET/CT) on radiotherapy planning for primary disease, biochemical cancer relapse, and advanced disease of prostate cancer.

METHODS

A total of 106 patients with prostate cancer scheduled for radiation therapy underwent 120 [⁶⁸Ga]PSMA PET/CT scans prior to radiotherapy treatment. In 20 cases, patients underwent [⁶⁸Ga]PSMA PET/CT for primary therapy (PT), 75 cases were referred for biochemical relapse after surgery (RL), and 25 cases were intended for palliative treatment of localized metastases (MD). We retrospectively compared the impact of [⁶⁸Ga]PSMA PET/CT on lesion detection and treatment decision to CT alone.

RESULTS

[⁶⁸Ga]PSMA PET/CT revealed a total of 271 positive lesions, whereas CT detected 86 lesions (32%). Overall, the radiotherapy regime was changed in 55 of 120 cases (46%) based on the higher detection rate of [⁶⁸Ga]PSMA PET/CT: in 15% of cases with PT, in 43% of cases with RL, and in 44% of cases with MD.

CONCLUSION

[⁶⁸Ga]PSMA PET/CT is superior to CT alone for lesion detection in prostate cancer, thereby significantly impacting on radiotherapy planning for primary disease, biochemical cancer relapse, and advanced disease of prostate cancer.

Does Choline PET/CT Change the Management of Prostate Cancer Patients With Biochemical Failure?

PURPOSE

The FDA approved C-11 choline PET/computed tomography (CT) for imaging patients with recurrent prostate cancer in 2012. Subsequently, the 2014 NCCN guidelines have introduced labeled choline PET/CT in the imaging algorithm of patients with suspected recurrent disease. However, there is only scarce data on the impact of labeled choline PET/CT findings on disease management. We hypothesized that labeled-choline PET/CT studies showing local or regional recurrence or distant metastases will have a direct role in selection of appropriate patient management and improve radiation planning in patients with disease that can be controlled using this mode of therapy.

METHODS

This retrospective study was approved by the Tel Aviv Sourasky and Sheba Medical Center's Helsinki ethical review committees. Patient characteristics including age, PSA, stage, prior treatments, and pre-PET choline treatment recommendations based on NCCN guidelines were recorded. Patients with biochemical failure and without evidence of recurrence on physical examination or standard imaging were offered the option of additional imaging with labeled choline PET/CT. Treatment recommendations post-PET/CT were compared with pre-PET/CT ones. Pathologic confirmation was obtained before prostate retreatment. A nonparametric χ test was used to compare the initial and final treatment recommendations following choline PET/CT.

RESULTS

Between June 2010 and January 2014, 34 labeled-choline PET/CT studies were performed on 33 patients with biochemical failure following radical prostatectomy (RP) (n=6), radiation therapy (RT) (n=6), brachytherapy (n=2), RP+salvage prostate fossa RT (n=14), and RP+salvage prostate fossa/lymph node RT (n=6). Median PSA level before imaging was 2 ng/mL (range, 0.16 to 79). Labeled choline PET/CT showed prostate, prostate fossa, or pelvic lymph node increased uptake in 17 studies, remote metastatic disease in 9 studies, and failed to identify the cause for biochemical failure in 7 scans.PET/CT altered treatment approach in 18 of 33 (55%) patients (P=0.05). Sixteen of 27 patients (59%) treated previously with radiation were retreated with RT and delayed or eliminated androgen deprivation therapy: 1 received salvage brachytherapy, 10 received salvage pelvic lymph node or prostate fossa irradiation, 2 brachytherapy failures received salvage prostate and lymph nodes IMRT, and 3 with solitary bone metastasis were treated with radiosurgery. Eleven of 16 patients retreated responded to salvage therapy with a significant PSA response (<0.2 ng/mL), 2 patients had partial biochemical responses, and 3 patients failed. The median duration of response was 500±447 days. Two of 6 patients with no prior RT were referred for salvage prostatic fossa RT: 1 received dose escalation for disease identified in the prostate fossa and another had inclusion of "hot" pelvic lymph nodes in the treatment volume.

CONCLUSIONS

These early results suggest that labeled choline PET/CT imaging performed according to current NCCN guidelines may change management and improve care in prostate cancer patients with biochemical failure by identifying patients for referral for salvage radiation therapy, improving radiation planning, and delaying or avoiding use of androgen deprivation therapy.

Imaging of Prostate Cancer Using 18F-Choline PET/Computed Tomography

¹⁸F-fluorocholine (FCH) PET/computed tomography (CT) is a valuable imaging modality in prostate cancer disease. Probably, its main role is restaging of patients with biochemical recurrence after radical prostatectomy or external beam radiotherapy. ¹⁸F-FCH PET/CT is strengthening its position in the initial staging, biopsy target definition, radiotherapy planning, and therapy monitoring. Gleason score and prostate-specific antigen value, doubling time, and velocity can influence positivity of ¹⁸F-FCH PET/CT. The influence of androgen deprivation therapy on choline uptake is not precisely clarified. Collaboration between nuclear medicine physicians, radiologists, urologists, oncologists, and radiotherapists is crucial to help patients with prostate cancer disease.

Impact of 18F-Fluciclovine PET on Target Volume Definition for Postprostatectomy Salvage Radiotherapy: Initial Findings from a Randomized Trial

The purpose of this study was to evaluate the role of the synthetic amino acid PET radiotracer ¹⁸F-fluciclovine in modifying the defined clinical and treatment-planning target volumes in postprostatectomy patients undergoing salvage radiotherapy and to evaluate the resulting dosimetric consequences to surrounding organs at risk. Methods: Ninety-six patients were enrolled in a randomized, prospective intention-to-treat clinical trial for potential salvage radiotherapy for recurrent prostate cancer after prostatectomy. The initial treatment plan was based on the results from conventional abdominopelvic CT and MRI. The 45 patients in the experimental arm also underwent abdominopelvic ¹⁸F-fluciclovine PET/CT, and the images were registered with the conventional images to determine whether the results would modify the initial treatment plan. The 51 patients in the control arm did not undergo ¹⁸F-fluciclovine PET/CT. For each patient, the clinical and treatment-planning target volumes that would have been treated before ¹⁸F-fluciclovine registration were compared with those after registration. For organs at risk (rectum, bladder, and penile bulb), the volumes receiving 40 Gy and 65 Gy before registration were compared with those after registration. Statistical comparisons were made using the paired t test. Acute genitourinary and gastrointestinal toxicity as defined by the Radiation Therapy Oncology Group was compared between the control and experimental arms using the χ² test. Results: In 24 cases, radiotherapy was planned to a clinical target volume consisting of the prostate bed alone (CTV) (64.8-66.6 Gy). In 21 cases, radiotherapy was planned to a clinical target volume consisting of the pelvis (CTV1) (45.0 Gy) followed by a boost to the prostate bed (CTV2) (19.8-25.2 Gy). In each case, the respective treatment-planning target volume expansion (PTV, PTV1, or PTV2) was 0.8 cm (0.6 cm posterior). With the exception of PTV2, all postregistration volumes were significantly larger than the corresponding preregistration volumes. Analysis of the rectum, bladder, and penile bulb volumes receiving 40 Gy and 60 Gy demonstrated that only the penile bulb volumes were significantly higher after registration. No significant differences in acute genitourinary or gastrointestinal toxicity were observed. Conclusion: Including information from ¹⁸F-fluciclovine PET in the treatment-planning process led to significant differences in the defined target volume, with higher doses to the penile bulb but no significant differences in rectal or bladder dose or in acute genitourinary or gastrointestinal toxicity. Longer follow-up is needed to determine the impact of ¹⁸F-fluciclovine PET on cancer control and late toxicity endpoints.

Newer positron emission tomography radiopharmaceuticals for radiotherapy planning: an overview

Positron emission tomography-computed tomography (PET-CT) has changed cancer imaging in the last decade, for better. It can be employed for radiation treatment planning of different cancers with improved accuracy and outcomes as compared to conventional imaging methods. (18)F-fluorodeoxyglucose remains the most widely used though relatively non-specific cancer imaging PET tracer. A wide array of newer PET radiopharmaceuticals has been developed for targeted imaging of different cancers. PET-CT with such new PET radiopharmaceuticals has also been used for radiotherapy planning with encouraging results. In the present review we have briefly outlined the role of PET-CT with newer radiopharmaceuticals for radiotherapy planning and briefly reviewed the available literature in this regard.

(68)Ga-PSMA-11 PET/CT: a new technique with high potential for the radiotherapeutic management of prostate cancer patients

PURPOSE

Radiotherapy is the main therapeutic approach besides surgery of localized prostate cancer. It relies on risk stratification and exact staging. This report analyses the potential of [(68)Ga]Glu-urea-Lys(Ahx)-HBED-CC ((68)Ga-PSMA-11), a new positron emission tomography (PET) tracer targeting prostate-specific membrane antigen (PSMA) for prostate cancer staging and individualized radiotherapy planning.

METHODS

A cohort of 57 patients with prostate cancer scanned with (68)Ga-PSMA-11 PET/CT for radiotherapy planning was retrospectively reviewed; 15 patients were at initial diagnosis and 42 patients at time of biochemical recurrence. Staging results of conventional imaging, including bone scintigraphy, CT or MRI, were compared with (68)Ga-PSMA ligand PET/CT results and the influence on radiotherapeutic management was quantified.

RESULTS

(68)Ga-PSMA ligand PET/CT had a dramatic impact on radiotherapy application in the presented cohort. In 50.8 % of the cases therapy was changed.

CONCLUSION

The presented imaging technique of (68)Ga-PSMA PET/CT could be a key technology for individualized radiotherapy management in prostate cancer.

Influence of (11)C-choline PET/CT on radiotherapy planning in prostate cancer

AIM

To evaluate the influence of (11)C-choline PET/CT on radiotherapy planning in prostate cancer patients.

BACKGROUND

Precise information on the extension of prostate cancer is crucial for the choice of an appropriate therapeutic strategy. (11)C-choline positron emission tomography ((11)C-choline PET/CT) has two roles in radiation oncology (RT): (1) patient selection for treatment and (2) target volume selection and delineation. In conjunction with high-accuracy techniques, it might offer an opportunity of dose escalation and better tumour control while sparing healthy tissues.

MATERIALS AND METHODS

We carried out a retrospective study in order to analyse RT planning modification based on (11)C-choline PET/CT in 16 prostate cancer patients. Patients were treated with hypofractionated step-and-shoot Intensity Modulated Radiotherapy (IMRT), or Volumetric Modulated Arc Therapy (VMAT), and a daily cone-beam CT for Image Guided Radiation Therapy (IGRT). All patients underwent a (11)C-choline-PET/CT scan prior to radiotherapy.

RESULTS

In 37.5% of cases, a re-delineation and new dose prescription occurred. Data show good preliminary clinical results in terms of biochemical control and toxicity. No gastrointestinal (GI)/genitourinary (GU) grade III toxicities were observed after a median follow-up of 9.5 months.

CONCLUSIONS

In our experience, concerning the treatment of prostate cancer (PCa), (11)C-choline PET/CT may be helpful in radiotherapy planning, either for dose escalation or exclusion of selected sites.

Advanced imaging for the early diagnosis of local recurrence prostate cancer after radical prostatectomy

Currently the diagnosis of local recurrence of prostate cancer (PCa) after radical prostatectomy (RT) is based on the onset of biochemical failure which is defined by two consecutive values of prostate-specific antigen (PSA) higher than 0.2 ng/mL. The aim of this paper was to review the current roles of advanced imaging in the detection of locoregional recurrence. A nonsystematic literature search using the Medline and Cochrane Library databases was performed up to November 2013. Bibliographies of retrieved and review articles were also examined. Only those articles reporting complete data with clinical relevance for the present review were selected. This review article is divided into two major parts: the first one considers the role of PET/CT in the restaging of PCa after RP; the second part is intended to provide the impact of multiparametric-MRI (mp-MRI) in the depiction of locoregional recurrence. Published data indicate an emerging role for mp-MRI in the depiction of locoregional recurrence, while the performance of PET/CT still remains unclear. Moreover Mp-MRI, thanks to functional techniques, allows to distinguish between residual glandular healthy tissue, scar/fibrotic tissue, granulation tissue, and tumour recurrence and it may also be able to assess the aggressiveness of nodule recurrence.