Materials and Methods Patient

From December 2002 to March 2004,14 patients underwent renal cryoablation therapy at Keio university hospital (Table 1). All patients were candidates for partial nephrectomy for renal malignancies (14 patients with RCC, 1 with metastatic sarcoma) and the renal tumors were less than 4 cm in diameter (mean, 2.2 ± 0.6 cm; range, 1.5-4.0 cm). The mean age of the patients was 57.1 ± 12.0 years (range, 41-81 years). Three of the patients were treated with chemotherapy for other malignancies, two had liver cirrhosis, and two received anticoagulant therapy for ischemic diseases. One patient had bilateral lesions. Thirteen patients were treated with laparoscopic cryoablation (transperitoneal or retroperitoneal approaches), and one was treated with CT-guided percutaneous cryoablation.

Technique

The laparoscopic approach used was dependent on the location of the tumor. Posterior, lateral, and lower anterolateral tumors were approached retroperi-toneally; anterior and upper anterolateral tumors were approached transperi-toneally. Three- or four-port procedures were employed with the patient in the lateral position under general anesthesia. Briefly, the operative steps included

Table 1. Patient characteristics

Case

Age (years)

Sex

Side

Tumor size (cm)

Approach

Background

1

49

F

L

4.0

Retro

Postchemotherapy

2

60

M

R

2.3

Laparo

3

53

M

R

2.4

Retro

Liver cirrhosis

4

60

M

R

1.6

Retro

Liver cirrhosis

5

41

M

L

3.5

Retro

6

56

M

L

1.6

Retro

Angina

7

50

M

L

2.2

Retro

8

46

F

L

2.3

Retro

Postchemotherapy

9

67

M

L

1.5

Retro

Postchemotherapy

10

45

M

R

2.1

Retro

11

81

M

R

1.7

Percutaneous (CT)

Angina

12

56

M

L

2.5

Retro

13

58

M

L

2.0

Retro

14

54

M

L

2.0

Retro

L, left;R, right;Retro, retroperitoneally;Laparo, laparoscopically;CT, computed-tomography-guided

L, left;R, right;Retro, retroperitoneally;Laparo, laparoscopically;CT, computed-tomography-guided mobilization of the kidney within Gerota's fascia; excision of the overlying perirenal fat for histologic examination; imaging of the tumor with a laparoscopic ultrasound probe; and laparoscopic needle biopsy of the tumor, followed by puncture renal cryoablation under laparoscopic and ultrasonographic guidance. A double freeze-thaw cycle was performed with the aim of extending the iceball approximately 1 cm beyond the edge of the tumor or reaching the temperature of the thermocouple, which was placed beyond the periphery of a tumor, less than -20°C. Care was taken to keep the bowel, ureter, and other adjacent organs away from the iceball. The Cryocare Surgical System (Endocare, Irvine, CA, USA) (Fig. 4), an argon-helium-based system, was used for cryoablation. A 3-mm CryoProbe (Endocare) was placed for tumors less than 20 mm in diameter, and a 5-mm probe for tumors 20 to 30 mm in diameter. The use of multiple cryoprobes was considered for tumors over 30 mm in diameter.The puncture was filled up with Fibrin glue and/or Gelfoam after removal of the cryoprobe.

CT-guided percutaneous cryoablation was performed with the patient prone under local anesthesia (Fig. 5). A 3-mm cryoprobe was placed with its corresponding pinnacle introducer sheath.

Results

The lesions were treated successfully in all 14 patients. One patient (case 3) had urine leakage from the ureter 3 days after cryoablation and needed treatment with a ureteral catheter. There were no other intraoperative or perioperative complications. The mean operative time was 194 ± 32min (range, 118-240min), and the estimated blood loss was less than 50 ml (Table 2). The mean first freezing time was 11.5 ± 2.8min (range, 7-17min), and the second was 11.9 ± 3.3min

Fig. 4. Cryocare Surgical System (Endocare, Irvine, CA, USA)

Fig. 5. Computed tomography (CT)-guided percutaneous cryoablation. a Outside appearance. b CT imaging b

Fig. 5. Computed tomography (CT)-guided percutaneous cryoablation. a Outside appearance. b CT imaging

(range, 5-20min). The lowest temperature of the thermocouple placed periphery was -29.8°C (range, -12.0 to -64.1°C). The average use of analgesics was 0.6 ± 1.0 times (range, 0-3) (Table 3). The mean length of return to normal activity was 4.3 ± 0.7 days (range, 3-6 days), except for the one patient with urine leakage. No patients needed readmission to the hospital after discharge. The mean serum creatinine level was 0.9 ± 0.3, 0.8 ± 0.4, and 0.9 ± 0.3mg/dl on day -1, day 1, and day 3, respectively (Fig. 6). CT imaging on day 2 did not show any complicated findings, including hemorrhage, and all the areas of cryoablation were not enhanced (Fig. 7).

Thirteen of the 14 patients did not have any findings of recurrence or metastasis on enhanced CT during follow-up (mean, 10.1 ± 5.2 months; range, 1-16

Table 2. Intraoperative data

Case

Operative time Probe (mm)

Thermocouple

Freeze 1 (min)

Freeze 2 (min)

(min)

(°C)

1

205

5 x 2

-40.2

10

11

2

205

5 x 1

-32.0

10

10

3

182

5 x 1

-12.0

13

12

4

170

3 x 1

-21.6

10

10

5

209

5 x 1

-23.7

15

12

6

240

3 x 1

-50.7

7

5

7

181

5 x 1

-34.9

10

12

8

124

5 x 1

-30.7

12

13

9

210

5 x 1

-26.3

8

20

10

215

5 x 1

-31.0

12

10

11a

240

3 x 1

15

15

12

118

5 x 1

-64.1

10

12

13

208

5 x 1

-27.6

17

10

14

165

5 x 1

-12.8

12

14

Mean,

194 ± 32

-29.8

11.5 ± 2.8

11.9 ± 3.3

a Case 11 underwent a

CT-guided percutaneous procedure

Table 3.

Postoperative data

Case

No. of

Return to

Complications

Follow-up (mo)

Recurrence

analgesics

normal activity

(days)

1

1

4

_

16

2

3

5

16

3

0

5

15

4

1

4

15

5

2

9

Ureteral injury

13

Local

6

0

5

12

7

0

6

12

8

0

4

11

9

2

4

11

10

0

4

9

11a

0

3

5

12

0

4

4

13

0

4

2

14

0

4

1

Mean

0.6

4.8 ± 1.5

10.1 ± 5.2

a Case 11 underwent a

CT-guided percutaneous procedure

Fig. 6. Renal function. Cryoablation did not affect renal function.BUN,Blood urea nitrogen; s-CR, serum creatinine; POD, post operative day

2002 So* 29

DFCIV n.Octo IIJ

\mtimwj j

rJt »4

Pre ope.

Day2

|40 00mm 0 G*1fl )QD MniiP'i ^ HF1&0

6 months

Fig. 7. Follow-up with serial CT (Case 2). The ablated lesion was not enhanced and became smaller on follow-up

Pre ope. Day 2

kv r* 100

3 months

6 months

Fig. 8. Local recurrence in Case 5. An enhanced lesion was recognized in the ablated area after 3 months of follow-up

Fig. 8. Local recurrence in Case 5. An enhanced lesion was recognized in the ablated area after 3 months of follow-up months), and renal function was well preserved over the period. Seven patients underwent needle biopsy 6 months after cryoablation, and there were no findings of malignancy. However, one patient, who had a 35-mm tumor ablated with one 5-mm probe, was diagnosed as having a local recurrence on CT after 3 months (Fig. 8), and he underwent laparoscopic radical nephrectomy 6 months after cryoablation.

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