Advances in cryoablation for pancreatic cancer

Abstract

Pancreatic carcinoma is a common cancer of the digestive system with a poor prognosis. It is characterized by insidious onset, rapid progression, a high degree of malignancy and early metastasis. At present, radical surgery is considered the only curative option for treatment, however, the majority of patients with pancreatic cancer are diagnosed too late to undergo surgery. The sensitivity of pancreatic cancer to chemotherapy or radiotherapy is also poor. As a result, there is no standard treatment for patients with advanced pancreatic cancer. Cryoablation is generally considered to be an effective palliative treatment for pancreatic cancer. It has the advantages of minimal invasion and improved targeting, and is potentially safe with less pain to the patients. It is especially suitable in patients with unresectable pancreatic cancer. However, our initial findings suggest that cryotherapy combined with 125-iodine seed implantation, immunotherapy or various other treatments for advanced pancreatic cancer can improve survival in patients with unresectable or metastatic pancreatic cancer. Although these findings require further in-depth study, the initial results are encouraging. This paper reviews the safety and efficacy of cryoablation, including combined approaches, in the treatment of pancreatic cancer.

Keywords: Combination therapy; Cryoablation; Cryoimmunotherapy; Pancreatic cancer.

Figure 1

Percutaneous cryoablation of pancreatic cancer under computed tomography guidance. The images were taken via the stomach. A: The cryoprobe (green arrow) was percutaneously inserted into the tumor at the head of the pancreas via the stomach (yellow arrow); B: The ice ball beginning to form (red arrow) following the application of argon gas; C: The ice ball (red arrow) surrounding the probe shows a gradual increase in size.

Figure 2

Percutaneous cryoablation of pancreatic cancer under enhanced computed tomography guidance. The images were taken via the left lobe of the liver. A: The tumor at the head of the pancreas (yellow arrow) is visible with high intensity; B: The probe (green arrow) was percutaneously inserted into the tumor via the left lobe of the liver; the ice ball appears as a dark area (red arrow).

Figure 3

Percutaneous cryoablation of pancreatic cancer under enhanced computed tomography guidance. The images were taken between the stomach and transverse colon. A: The tumor at the head of the pancreas (yellow arrow) is visible with high intensity; B: The probe (green arrow) was percutaneously inserted into the tumor between the stomach and transverse colon; the ice ball is shown as a dark area (red arrow).

Figure 4

Percutaneous cryoablation of pancreatic cancer under enhanced computed tomography guidance. The images represent transdorsal approaches. A: The tumor at the head of the pancreas can be seen with high intensity (yellow arrow); B: The probe (green arrow) was inserted percutaneously into the tumor via a transdorsal approach; C: Ice ball formation appears as a dark area (red arrow); D: The size of the ice ball covers the entire area of tumor.

Figure 5

Comparisons between computed tomography images of pancreatic carcinoma before, during and 1.5 mo after cryoablation. A: The tumor at stage IV (red arrows) is 4.5 cm × 4.6 cm × 3.8 cm in size; B: The cryoprobe was inserted via the stomach approaching the tumor mass (yellow arrow); cryoablation was performed after the pancreatic tumor was completely encased within the ice ball (green arrows); C: The center of the tumor mass (red arrows) 1.5 mo post-cryoablation displays shrinkage with no enhancement of the tumor.

Figure 6

Pancreatic computed tomography scans before and after cryosurgery combined with 125-iodine seed implantation. A: Pancreatic lesions before treatment; B: Shrinkage of the pancreatic tumor one month post-treatment; C: Total shrinkage of the pancreatic tumor 6 mo post-treatment.

Figure 7

Survival plots of 67 patients with advanced pancreatic cancer after percutaneous cryoablation combined with 125-iodine seed implantation and chemotherapy. A: Progression-free survival curves for all 67 patients following treatment; B: Overall survival curves for all 67 patients following the combined treatment; C: Progression-free survival curves for patients with stages III and IV advanced pancreatic cancer post-treatment; D: Overall survival curves for patients with stages III and IV advanced pancreatic cancer post-treatment.

Figure 8

Pancreatic computed tomography scans of patients who received cryosurgery combined with 125-iodine seed implantation before and after treatment. A: Before treatment; B: 3 mo post-treatment; C: 12 mo post-treatment.

Figure 9

Correlation between overall survival and the number of cryoablation treatments in patients with pancreatic cancer. A: Comparisons of overall survival in the cryoimmunotherapy group between 13 patients who underwent repeated cryoablation and 18 patients who received a single cryoablation procedure; B: Comparisons of overall survival in the cryotherapy group between 15 patients who underwent repeated cryoablation and 21 patients who underwent a single cryoablation procedure. The analyses were performed by the Kaplan-Meier method with long-rank tests.

Figure 10

Correlation of overall survival with pretreatment immunologic indexes. A: Comparison between overall survival in 21 patients with immunologic indexes ≥ the reference range and 10 patients with immunologic indexes < the reference range in the cryoimmunotherapy group; B: Comparison between overall survival in 10 patients with immunologic indexes ≥ the reference range and 7 patients with immunologic indexes < the reference range in the immunotherapy group. The analyses were performed by the Kaplan-Meier method with long-rank tests.