- Email: [email protected]
Salvage CT-guided Transgluteal Cryoablation for Locally Recurrent Prostate Cancer: Initial Experiences
BRIEF REPORT
Salvage CT-guided Transgluteal Cryoablation for Locally Recurrent Prostate Cancer: Initial Experiences Francois Cornelis, MD, Marion Havez, MD, Yann Le Bras, MD, Edouard Descat, MD, Pierre Richaud, MD, and Nicolas Grenier, MD
ABSTRACT Technical feasibility of a computed tomography (CT)-guided transgluteal approach for salvage cryoablation of inoperable locally recurrent prostate cancer was evaluated retrospectively. Five procedures were performed under general anesthesia in five patients previously treated with radiation therapy. Median age was 64 years, and average pretreatment prostate-specific antigen (PSA) level was 2.77 ng/dL (range, 0.56–4.23 ng/dL). Each cryoablation procedure was completed in one session. No complications were reported. Mean 3-month and 6-month PSA levels were 0.35 ng/dL (range, 0.16–0.54 ng/dL) and 0.51 ng/dL (range, 0.09–0.94 ng/dL), respectively, representing mean decreases of 84% (range, 71%–92%) and 81% (range, 78%–84%), respectively. Salvage CT-guided transgluteal cryoablation of the prostate therefore appears technically feasible.
ABBREVIATIONS PSA = prostate-specific antigen, RT = radiation therapy
Therapeutic management of recurrent prostate cancer after radiation therapy (RT) remains challenging because early recurrence develops in most patients irrespective of treatment received (1). Various surgical or percutaneous approaches such as cryoablation have been tested in attempts to develop alternative therapeutic strategies with better recurrence-free survival, without compromising quality of life (2). Because ultrasound (US) methods are not sufficient to monitor ice growth during cryoablation, magnetic resonance (MR) guidance has been recently proposed in this indication (3). However, because these MR-guided procedures are still a technical challenge and data from other organs indicates that computed tomography (CT)-guided cryoablation is also effective (4), the present preliminary report aims to evaluate the technical feasibility of CT-guided percutaneous cryoablation for
From the Department of Radiology (F.C., M.H., Y.L.B., N.G.), Pellegrin Hospital, Place Ame´lie Raba Le´on, 33076 Bordeaux, France; and Departments of Radiology (F.C., E.D.) and Radiotherapy (P.R.), Institut Bergonie´, Bordeaux, France. Received October 26, 2012; final revision received January 15, 2013; accepted January 21, 2013. Address correspondence to F.C.; E-mail: [email protected] None of the authors have identified a conflict of interest. & SIR, 2013 J Vasc Interv Radiol 2013; 24:685–689 http://dx.doi.org/10.1016/j.jvir.2013.01.493
recurrence of prostate cancer through a direct transgluteal approach.
MATERIALS AND METHODS This retrospective study was approved by the institutional review board, and informed consent was waived. All patients who underwent a CT-guided cryoablation between November 2011 and April 2012 for a recurrent prostate cancer were selected consecutively from our prospectively maintained institutional database. Five procedures in five patients were identified (Table). Patients’ ages ranged from 58 to 69 years (median, 66 y), with a mean pretreatment prostate-specific antigen (PSA) level of 2.77 ng/dL (range, 0.56–4.23 ng/dL). All patients had a history of prostate cancer with continuously increasing PSA level. Initial Gleason scores ranged from 6 to 7, and serum PSA levels ranged from 7.29 to 9.84 ng/dL. All patients had a history of primary (n ¼ 3) or secondary (n ¼ 2) RT delivered 103– 173 months before cryoablation. In planning the cryoablation, tumor recurrence was assessed in all patients by contrast-enhanced US-guided transrectal biopsy with Sulphur Hexafluoride microbubbles (Sonovue, 2.4 mL; Bracco, Milan, Italy) following a contrast MR imaging examination (Aera 1.5-T; Siemens, Erlangen, Germany). Nontargeted biopsies were also performed. A single recurrence was clearly visualized for all patients by using either technique. The recurrence was
686
’
Salvage CT-guided Cryoablation for Recurrent Prostate Cancer
Cornelis et al
’
JVIR
Table . Patient Characteristics and Outcomes for Patients with Locally Recurrent Prostate Cancer Treated by CT-guided Transgluteal Cryoablation Nadir PSA
Recurrence
Initial Stage
Previous Treatments
(ng/mL)
PSA Gleason Score
Localization
(ng/mL)
on MR
1/69
T3a
RTT, HT
0.56
3þ3
Right apex
0.09
No
2/61 3/66
pT3a T3a
RP, RT, HT RT, HT
2.84 4.23
5þ3 3þ4
Pelvis Right apex
1.5 0.94
Local No
Pt. No./Age (y)
4/66
T3a
RT, HT
4.0
3þ3
Right apex
0.3
No
5/58
pT2c
RP, RT, HT
2.21
3þ4
Left seminal vesicle
0.4
No
There were no severe complications in any patient. HT ¼ hormonal therapy, PSA ¼ prostate-specific antigen, RP ¼ radical prostatectomy, RT ¼ radiation therapy, RTT ¼ radiotherapy.
situated on the right apex into the peripheral zone in three patients, laterally to the rectum in one, and in the left seminal vesicle in one. The pathology analysis concluded there was a focal recurrence in all cases. Gleason scores at recurrence ranged from 6 to 7, except for the patient with pelvic recurrence laterally to the rectum, who had an undifferentiated carcinoma with a Gleason score of 8. Biopsies were performed an average of 57 days before cryoablation (range, 15–85 d). Preoperative bone or positron emission tomography/CT scans obtained an average of 78 days before cryoablation (range, 48–111 d), were negative for metastatic disease in all patients, and they were treated with hormonal blockade. After discussion in a multidisciplinary team meeting, salvage surgery and highintensity focused US were rejected in view of the location of the tumors and coexisting or expected morbidity. Radical salvage prostatectomy was deferred for the three patients who had received primary RT in view of the location of recurrence and severe comorbidities such as cardiac pathologic conditions (mechanical mitral valve and chronic pericardial effusion) and chronic respiratory insufficiency. All patients received a rectal enema the night before the procedure. Under general anesthesia, a urethral catheter was positioned without the need for a warming device as a result of the distance between the targeted zone and the urethra. Patients were placed in the left or right lateral decubitus position in a conventional CT unit. To cover the entire targeted tumor, an ablation of the hemiprostate in which the tumor was located was planned. A single session of cryoablation was performed under CT guidance. Mean procedural time was 53 minutes (range, 50–60 min). For all procedures, only two 17-gauge cryoprobes (IceRod or IceSphere; Galil Medical, Yokneam, Israel) were introduced into the prostate through a transgluteal approach, laterally to the mesorectum, and distant from the neurovascular structures (Fig 1). A CO2 dissection was performed into the mesorectum to displace the rectum and the neurovascular bundles by using a 22-gauge needle advanced through the same transgluteal pathway for all patients. The rectum was protected with a warming enema at 371C that was kept in place until the patients left the operating room.
The freezing process was monitored in real time by CT for direct visualization of the ice ball and to avoid lesions to adjacent tissues. At the end of all cryoablation cycles (10min freeze followed by 9-min passive and 1-min active thaw, followed by 10-min freeze), the ice covered the entire targeted tumor. Thereafter, the probes were removed through active thawing. No immediate complications were reported. All patients were discharged, with the urethral catheter removed within 3 days. Patient characteristics and treatment received were recorded, as were posttreatment complications, technical success (defined as complete coverage of the entire targeted zone), and local recurrence. Clinical, biological (ie, PSA), and multiparametric MR imaging follow-up was planned at 3 and 6 months to assess for local recurrence.
RESULTS No immediate postprocedural complications were reported according to the Society of Interventional Radiology guidelines (5). All patients were discharged and the urethral catheter was removed within 3 days. No major complications were reported. No erectile dysfunction was reported in either of the two previously potent patients. Postoperative low-grade pain resolved progressively 3 weeks after cryoablation in all cases. No pain was reported at 1, 3, or 6 months by all patients. Technical success was obtained after one session of cryoablation in all patients. The clinical and imaging follow-up period ranged from 6 to 10 months (median, 8 mo). The three patients who had previously received primary RT and the patient with recurrence in the left seminal vesicle had no evidence of local recurrence on MR imaging at 3 and 6 months. For these four patients, the mean PSA level at 1 month after treatment was 0.37 ng/dL (range, 0.16–0.65 ng/dL). The mean PSA level at 3 months was 0.34 ng/dL (range, 0.16–0.54 ng/dL), representing a mean decrease of 79% (range, 71%–92%), and the mean PSA level at 6 months was 0.51 ng/dL (range, 0.09–0.94 ng/dL), representing a mean decrease of 81% (range, 78%–84%). The patient with a history of initial surgery and secondary RT for an undifferentiated
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Figure 1. (a) Axial T2-weighted image (TR: 2112 ms/TE: 100 ms/flip angle [FA]: 901) shows right apex hypointense tumor in a 69-yearold man (arrow) corresponding to a biopsy-proven prostate carcinoma with a Gleason score of 6 (ie, 3 þ 3). (b) Axial early postcontrast T1-weighted image (TR: 3.9 ms/TE: 1.8 ms/FA: 101) without fat suppression obtained 40 seconds after gadolinium injection shows a 9-mm fast enhancement. (c) Nonenhanced CT-guided cryoablation shows the ice ball (solid arrow) and the mesorectum carbodissection after insertion of a 22-gauge needle (dashed arrow). (d) Axial postcontrast T1-weighted image (TR: 3.9 ms/TE: 1.8 ms/FA: 101) with fat suppression shows no residual enhancement in the ablative zone.
carcinoma (Gleason score 8) had an asymptomatic local recurrence on the 3-month MR examination outside the ablative site as a result of progression of the disease, without clinical symptoms (Fig 2). Chemotherapy was then proposed.
DISCUSSION As shown in this initial study, CT-guided transgluteal percutaneous cryoablation offers similar local control to a surgical or perineal approach, with few and only minor complications reported (2,6,7). One factor that probably reduced the rate of complications was that we used only fourth-generation cryoprobes (8) that have a smaller size (17-gauge) than previous devices. Moreover, the percutaneous transgluteal approach required fewer cryoprobes, limiting the complexity of each procedure. Interestingly, the anatomy of the prostate—often much wider than it was high (9)—and the targeted volume were suited to the ovoid shape of the ice ball. This approach also prevented rectourethral fistula or pelvic ground injuries, but required a percutaneous carbodissection for safety. Carbodissection of the mesorectum was straightforward to carry out, used the same access site used for cryoablation, and successfully limited ice ball extension to critical structures surrounding the target zone (10), such as the neurovascular bundles and rectum.
As proposed for other organs, real-time monitoring of ice growth with CT was technically easy and time-efficient, even though MR monitoring may be superior regarding adequate real-time tumor localization (3). Multiplanar reconstructions were useful to monitor the volume and extension of the ice ball. The volume was dependent on the freezing power of each cryoprobe and could be modified in real time to prevent overextension of the ice ball and thermal damage to neighboring structures such as the rectal wall, urethra, or neurovascular bundles. In addition, if an inadequate coverage of the targeted prostate was suspected, the cryoprobe position was adjusted. As the urethral tract was clearly visualized during ice growth, even after insertion of a urethral catheter, no warming device was used. However, use of a warming device may be necessary in future larger studies to avoid thermal injury to the urethra. As for all focal therapy, the success of transgluteal cryoablation is dependent on careful selection of patients who have confined disease. To ensure the technical success of the procedure, the size and location of recurrent lesions are very important, and a rigorous imaging protocol is required so as not to miss extensive disease. When the recurrent lesions are located too close to neurovascular bundles or the rectum, safety can not be guaranteed, even after carbodissection. When recurrent lesions are irregular in shape and too large, curative ablation might fail; however, cryosurgery could be proposed in these cases.
688
’
Salvage CT-guided Cryoablation for Recurrent Prostate Cancer
Cornelis et al
’
JVIR
Figure 2. (a) Axial T2-weighted images (TR: 2112 ms/TE: 100 ms/flip angle [FA]: 901) show a recurrence of disease on the right side, with a Gleason score of 8 (ie, 5 þ 3), in a 61-year-old man (arrow). Nonenhanced CT scans before (b) and after cryoablation (c) show the ice ball enclosing the whole mass. (d) Axial postcontrast T1-weighted images (TR: 3.9 ms/TE: 1.8 ms/FA: 101) with fat suppression show no residual enhancement in the ablative zone on 3-month follow-up but new enhancements outside the ablative site (dashed arrow).
For these reasons, all patients included in the present study had a preoperative bone or positron emission tomography/ CT scan and a complete prostate MR examination, followed by real-time contrast-enhanced US–targeted biopsies. The latter was believed to be essential because conventional transrectal US biopsies may be nondiagnostic if performed alone, and often cannot accurately define relative tumor location (11). Although this approach appears to fail in cases of progressive disease (as observed in one case in the present study), it is possible to achieve local control of the disease, even in cases of disease extension outside the prostate. Based on the report that early salvage surgery for biopsy-proven local treatment failure leads to more favorable outcomes, often not necessitating adjuvant hormonal therapy (12), a technically easy CT-guided cryoablation could be proposed in these indications, with lower morbidity. The present brief study has some limitations related to the small number of patients and the short follow-up. In addition, prostate cancer recurrences were not visualized well on CT. The feasibility of the transgluteal approach depended on the location of the tumor and/or the decreased size of the prostate gland after RT. Our technique was based on a cognitive fusion of imaging modalities including preoperative MR imaging, or contrast-enhanced US, and CT. A combined approach with contrast-enhanced US could improve the accuracy of tumor localization without compromising procedural complexity.
In conclusion, based on the present initial study, CTguided percutaneous cryoablation seems to be technically feasible with promising results. This procedure now needs to be evaluated in larger studies with longer follow-up to assess whether it can be proposed as an alternative for the treatment of recurrence of prostate cancer.
ACKNOWLEDGMENTS The authors thank Pippa McKelvie-Sebileau for medical editorial assistance in English.
REFERENCES 1. Chade DC, Eastham J, Graefen M, et al. Cancer control and functional outcomes of salvage radical prostatectomy for radiation-recurrent prostate cancer: a systematic review of the literature. Eur Urol 2012; 61:961–971. 2. Bahn DK, Silverman P, Lee F, Badalament R, Bahn ED, Rewcastle JC. Focal prostate cryoablation: initial results show cancer control and potency preservation. J Endourol 2006; 20:688–692. 3. Gangi A, Tsoumakidou G, Abdelli O, et al. Percutaneous MR-guided cryoablation of prostate cancer: initial experience. Eur Radiol 2012; 22: 1829–1835. 4. Kunkle DA, Uzzo RG. Cryoablation or radiofrequency ablation of the small renal mass: a meta-analysis. Cancer 2008; 113:2671–2680. 5. Sacks D, McClenny TE, Cardella JF, Lewis CA. Society of Interventional Radiology clinical practice guidelines. J Vasc Interv Radiol 2003; 14(suppl):S199–S202. 6. Donnelly BJ, Saliken JC, Brasher PMA, et al. A randomized trial of external beam radiotherapy versus cryoablation in patients with localized prostate cancer. Cancer 2010; 116:323–330.
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7. Onik G, Vaughan D, Lotenfoe R, Dineen M, Brady J. The ‘‘male lumpectomy’’: focal therapy for prostate cancer using cryoablation results in 48 patients with at least 2-year follow-up. Urol Oncol 2008; 26:500–505. 8. Mouraviev V, Spiess PE, Jones JS. Salvage cryoablation for locally recurrent prostate cancer following primary radiotherapy. Eur Urol 2012; 61:1204–1211. 9. Fine SW, Reuter VE. Anatomy of the prostate revisited: implications for prostate biopsy and zonal origins of prostate cancer. Histopathology 2012; 60:142–152.
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10. Buy X, Tok CH, Szwarc D, Bierry G, Gangi A. Thermal protection during percutaneous thermal ablation procedures: interest of carbon dioxide dissection and temperature monitoring. Cardiovasc Intervent Radiol 2009; 32:529–534. 11. de la Rosette J, Ahmed H, Barentsz J, et al. Focal therapy in prostate cancer-report from a consensus panel. J Endourol 2010; 24:775–780. 12. Sanderson KM, Penson DF, Cai J, et al. Salvage radical prostatectomy: quality of life outcomes and long-term oncological control of radiorecurrent prostate cancer. J Urol 2006; 176:2025–2031.
Salvage CT-guided Transgluteal Cryoablation for Locally Recurrent Prostate Cancer: Initial Experiences Francois Cornelis, MD, Marion Havez, MD, Yann Le Bras, MD, Edouard Descat, MD, Pierre Richaud, MD, and Nicolas Grenier, MD
ABSTRACT Technical feasibility of a computed tomography (CT)-guided transgluteal approach for salvage cryoablation of inoperable locally recurrent prostate cancer was evaluated retrospectively. Five procedures were performed under general anesthesia in five patients previously treated with radiation therapy. Median age was 64 years, and average pretreatment prostate-specific antigen (PSA) level was 2.77 ng/dL (range, 0.56–4.23 ng/dL). Each cryoablation procedure was completed in one session. No complications were reported. Mean 3-month and 6-month PSA levels were 0.35 ng/dL (range, 0.16–0.54 ng/dL) and 0.51 ng/dL (range, 0.09–0.94 ng/dL), respectively, representing mean decreases of 84% (range, 71%–92%) and 81% (range, 78%–84%), respectively. Salvage CT-guided transgluteal cryoablation of the prostate therefore appears technically feasible.
ABBREVIATIONS PSA = prostate-specific antigen, RT = radiation therapy
Therapeutic management of recurrent prostate cancer after radiation therapy (RT) remains challenging because early recurrence develops in most patients irrespective of treatment received (1). Various surgical or percutaneous approaches such as cryoablation have been tested in attempts to develop alternative therapeutic strategies with better recurrence-free survival, without compromising quality of life (2). Because ultrasound (US) methods are not sufficient to monitor ice growth during cryoablation, magnetic resonance (MR) guidance has been recently proposed in this indication (3). However, because these MR-guided procedures are still a technical challenge and data from other organs indicates that computed tomography (CT)-guided cryoablation is also effective (4), the present preliminary report aims to evaluate the technical feasibility of CT-guided percutaneous cryoablation for
From the Department of Radiology (F.C., M.H., Y.L.B., N.G.), Pellegrin Hospital, Place Ame´lie Raba Le´on, 33076 Bordeaux, France; and Departments of Radiology (F.C., E.D.) and Radiotherapy (P.R.), Institut Bergonie´, Bordeaux, France. Received October 26, 2012; final revision received January 15, 2013; accepted January 21, 2013. Address correspondence to F.C.; E-mail: [email protected] None of the authors have identified a conflict of interest. & SIR, 2013 J Vasc Interv Radiol 2013; 24:685–689 http://dx.doi.org/10.1016/j.jvir.2013.01.493
recurrence of prostate cancer through a direct transgluteal approach.
MATERIALS AND METHODS This retrospective study was approved by the institutional review board, and informed consent was waived. All patients who underwent a CT-guided cryoablation between November 2011 and April 2012 for a recurrent prostate cancer were selected consecutively from our prospectively maintained institutional database. Five procedures in five patients were identified (Table). Patients’ ages ranged from 58 to 69 years (median, 66 y), with a mean pretreatment prostate-specific antigen (PSA) level of 2.77 ng/dL (range, 0.56–4.23 ng/dL). All patients had a history of prostate cancer with continuously increasing PSA level. Initial Gleason scores ranged from 6 to 7, and serum PSA levels ranged from 7.29 to 9.84 ng/dL. All patients had a history of primary (n ¼ 3) or secondary (n ¼ 2) RT delivered 103– 173 months before cryoablation. In planning the cryoablation, tumor recurrence was assessed in all patients by contrast-enhanced US-guided transrectal biopsy with Sulphur Hexafluoride microbubbles (Sonovue, 2.4 mL; Bracco, Milan, Italy) following a contrast MR imaging examination (Aera 1.5-T; Siemens, Erlangen, Germany). Nontargeted biopsies were also performed. A single recurrence was clearly visualized for all patients by using either technique. The recurrence was
686
’
Salvage CT-guided Cryoablation for Recurrent Prostate Cancer
Cornelis et al
’
JVIR
Table . Patient Characteristics and Outcomes for Patients with Locally Recurrent Prostate Cancer Treated by CT-guided Transgluteal Cryoablation Nadir PSA
Recurrence
Initial Stage
Previous Treatments
(ng/mL)
PSA Gleason Score
Localization
(ng/mL)
on MR
1/69
T3a
RTT, HT
0.56
3þ3
Right apex
0.09
No
2/61 3/66
pT3a T3a
RP, RT, HT RT, HT
2.84 4.23
5þ3 3þ4
Pelvis Right apex
1.5 0.94
Local No
Pt. No./Age (y)
4/66
T3a
RT, HT
4.0
3þ3
Right apex
0.3
No
5/58
pT2c
RP, RT, HT
2.21
3þ4
Left seminal vesicle
0.4
No
There were no severe complications in any patient. HT ¼ hormonal therapy, PSA ¼ prostate-specific antigen, RP ¼ radical prostatectomy, RT ¼ radiation therapy, RTT ¼ radiotherapy.
situated on the right apex into the peripheral zone in three patients, laterally to the rectum in one, and in the left seminal vesicle in one. The pathology analysis concluded there was a focal recurrence in all cases. Gleason scores at recurrence ranged from 6 to 7, except for the patient with pelvic recurrence laterally to the rectum, who had an undifferentiated carcinoma with a Gleason score of 8. Biopsies were performed an average of 57 days before cryoablation (range, 15–85 d). Preoperative bone or positron emission tomography/CT scans obtained an average of 78 days before cryoablation (range, 48–111 d), were negative for metastatic disease in all patients, and they were treated with hormonal blockade. After discussion in a multidisciplinary team meeting, salvage surgery and highintensity focused US were rejected in view of the location of the tumors and coexisting or expected morbidity. Radical salvage prostatectomy was deferred for the three patients who had received primary RT in view of the location of recurrence and severe comorbidities such as cardiac pathologic conditions (mechanical mitral valve and chronic pericardial effusion) and chronic respiratory insufficiency. All patients received a rectal enema the night before the procedure. Under general anesthesia, a urethral catheter was positioned without the need for a warming device as a result of the distance between the targeted zone and the urethra. Patients were placed in the left or right lateral decubitus position in a conventional CT unit. To cover the entire targeted tumor, an ablation of the hemiprostate in which the tumor was located was planned. A single session of cryoablation was performed under CT guidance. Mean procedural time was 53 minutes (range, 50–60 min). For all procedures, only two 17-gauge cryoprobes (IceRod or IceSphere; Galil Medical, Yokneam, Israel) were introduced into the prostate through a transgluteal approach, laterally to the mesorectum, and distant from the neurovascular structures (Fig 1). A CO2 dissection was performed into the mesorectum to displace the rectum and the neurovascular bundles by using a 22-gauge needle advanced through the same transgluteal pathway for all patients. The rectum was protected with a warming enema at 371C that was kept in place until the patients left the operating room.
The freezing process was monitored in real time by CT for direct visualization of the ice ball and to avoid lesions to adjacent tissues. At the end of all cryoablation cycles (10min freeze followed by 9-min passive and 1-min active thaw, followed by 10-min freeze), the ice covered the entire targeted tumor. Thereafter, the probes were removed through active thawing. No immediate complications were reported. All patients were discharged, with the urethral catheter removed within 3 days. Patient characteristics and treatment received were recorded, as were posttreatment complications, technical success (defined as complete coverage of the entire targeted zone), and local recurrence. Clinical, biological (ie, PSA), and multiparametric MR imaging follow-up was planned at 3 and 6 months to assess for local recurrence.
RESULTS No immediate postprocedural complications were reported according to the Society of Interventional Radiology guidelines (5). All patients were discharged and the urethral catheter was removed within 3 days. No major complications were reported. No erectile dysfunction was reported in either of the two previously potent patients. Postoperative low-grade pain resolved progressively 3 weeks after cryoablation in all cases. No pain was reported at 1, 3, or 6 months by all patients. Technical success was obtained after one session of cryoablation in all patients. The clinical and imaging follow-up period ranged from 6 to 10 months (median, 8 mo). The three patients who had previously received primary RT and the patient with recurrence in the left seminal vesicle had no evidence of local recurrence on MR imaging at 3 and 6 months. For these four patients, the mean PSA level at 1 month after treatment was 0.37 ng/dL (range, 0.16–0.65 ng/dL). The mean PSA level at 3 months was 0.34 ng/dL (range, 0.16–0.54 ng/dL), representing a mean decrease of 79% (range, 71%–92%), and the mean PSA level at 6 months was 0.51 ng/dL (range, 0.09–0.94 ng/dL), representing a mean decrease of 81% (range, 78%–84%). The patient with a history of initial surgery and secondary RT for an undifferentiated
Volume 24
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’
2013
687
Figure 1. (a) Axial T2-weighted image (TR: 2112 ms/TE: 100 ms/flip angle [FA]: 901) shows right apex hypointense tumor in a 69-yearold man (arrow) corresponding to a biopsy-proven prostate carcinoma with a Gleason score of 6 (ie, 3 þ 3). (b) Axial early postcontrast T1-weighted image (TR: 3.9 ms/TE: 1.8 ms/FA: 101) without fat suppression obtained 40 seconds after gadolinium injection shows a 9-mm fast enhancement. (c) Nonenhanced CT-guided cryoablation shows the ice ball (solid arrow) and the mesorectum carbodissection after insertion of a 22-gauge needle (dashed arrow). (d) Axial postcontrast T1-weighted image (TR: 3.9 ms/TE: 1.8 ms/FA: 101) with fat suppression shows no residual enhancement in the ablative zone.
carcinoma (Gleason score 8) had an asymptomatic local recurrence on the 3-month MR examination outside the ablative site as a result of progression of the disease, without clinical symptoms (Fig 2). Chemotherapy was then proposed.
DISCUSSION As shown in this initial study, CT-guided transgluteal percutaneous cryoablation offers similar local control to a surgical or perineal approach, with few and only minor complications reported (2,6,7). One factor that probably reduced the rate of complications was that we used only fourth-generation cryoprobes (8) that have a smaller size (17-gauge) than previous devices. Moreover, the percutaneous transgluteal approach required fewer cryoprobes, limiting the complexity of each procedure. Interestingly, the anatomy of the prostate—often much wider than it was high (9)—and the targeted volume were suited to the ovoid shape of the ice ball. This approach also prevented rectourethral fistula or pelvic ground injuries, but required a percutaneous carbodissection for safety. Carbodissection of the mesorectum was straightforward to carry out, used the same access site used for cryoablation, and successfully limited ice ball extension to critical structures surrounding the target zone (10), such as the neurovascular bundles and rectum.
As proposed for other organs, real-time monitoring of ice growth with CT was technically easy and time-efficient, even though MR monitoring may be superior regarding adequate real-time tumor localization (3). Multiplanar reconstructions were useful to monitor the volume and extension of the ice ball. The volume was dependent on the freezing power of each cryoprobe and could be modified in real time to prevent overextension of the ice ball and thermal damage to neighboring structures such as the rectal wall, urethra, or neurovascular bundles. In addition, if an inadequate coverage of the targeted prostate was suspected, the cryoprobe position was adjusted. As the urethral tract was clearly visualized during ice growth, even after insertion of a urethral catheter, no warming device was used. However, use of a warming device may be necessary in future larger studies to avoid thermal injury to the urethra. As for all focal therapy, the success of transgluteal cryoablation is dependent on careful selection of patients who have confined disease. To ensure the technical success of the procedure, the size and location of recurrent lesions are very important, and a rigorous imaging protocol is required so as not to miss extensive disease. When the recurrent lesions are located too close to neurovascular bundles or the rectum, safety can not be guaranteed, even after carbodissection. When recurrent lesions are irregular in shape and too large, curative ablation might fail; however, cryosurgery could be proposed in these cases.
688
’
Salvage CT-guided Cryoablation for Recurrent Prostate Cancer
Cornelis et al
’
JVIR
Figure 2. (a) Axial T2-weighted images (TR: 2112 ms/TE: 100 ms/flip angle [FA]: 901) show a recurrence of disease on the right side, with a Gleason score of 8 (ie, 5 þ 3), in a 61-year-old man (arrow). Nonenhanced CT scans before (b) and after cryoablation (c) show the ice ball enclosing the whole mass. (d) Axial postcontrast T1-weighted images (TR: 3.9 ms/TE: 1.8 ms/FA: 101) with fat suppression show no residual enhancement in the ablative zone on 3-month follow-up but new enhancements outside the ablative site (dashed arrow).
For these reasons, all patients included in the present study had a preoperative bone or positron emission tomography/ CT scan and a complete prostate MR examination, followed by real-time contrast-enhanced US–targeted biopsies. The latter was believed to be essential because conventional transrectal US biopsies may be nondiagnostic if performed alone, and often cannot accurately define relative tumor location (11). Although this approach appears to fail in cases of progressive disease (as observed in one case in the present study), it is possible to achieve local control of the disease, even in cases of disease extension outside the prostate. Based on the report that early salvage surgery for biopsy-proven local treatment failure leads to more favorable outcomes, often not necessitating adjuvant hormonal therapy (12), a technically easy CT-guided cryoablation could be proposed in these indications, with lower morbidity. The present brief study has some limitations related to the small number of patients and the short follow-up. In addition, prostate cancer recurrences were not visualized well on CT. The feasibility of the transgluteal approach depended on the location of the tumor and/or the decreased size of the prostate gland after RT. Our technique was based on a cognitive fusion of imaging modalities including preoperative MR imaging, or contrast-enhanced US, and CT. A combined approach with contrast-enhanced US could improve the accuracy of tumor localization without compromising procedural complexity.
In conclusion, based on the present initial study, CTguided percutaneous cryoablation seems to be technically feasible with promising results. This procedure now needs to be evaluated in larger studies with longer follow-up to assess whether it can be proposed as an alternative for the treatment of recurrence of prostate cancer.
ACKNOWLEDGMENTS The authors thank Pippa McKelvie-Sebileau for medical editorial assistance in English.
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