Using the New INTRABEAM Mobile Intraoperative Radiotherapy System During Surgery for Pancreatic Cancer

A Case Report

Xiaodong Song; Zili Shao; Huihong Liang

Disclosures

J Med Case Reports. 2019;13(23) 

In This Article

Discussion

Here we present a successful case of pancreatic cancer. Our patient underwent distal pancreatectomy and splenectomy along with IORT using a portable INTRABEAM radiation system. This low-energy IORT system is available to eliminate possible residual malignancies. Furthermore, it avoids the risks of severe radiotherapy-associated complications that are associated with traditional IORT.

There is a clear, increasing trend in the global incidence of pancreatic cancer, which has an extremely poor prognosis: the 5-year survival rate is < 5%.[12] Surgery is the only effective and curative treatment for pancreatic cancer, although < 25% of patients with pancreatic cancer can undergo radical surgical treatment. In addition, local recurrence develops in 50–90% of patients who undergo surgical resection, and the local recurrence rate remains high even after extensive resection. Radiotherapy is a useful palliative procedure that can provide relief from pain and other symptoms, including local pain relief in patients with unresectable tumors, which can help prolong survival and preserve quality of life. However, traditional external radiation therapy using extracorporeal irradiation can easily lead to severe complications and suboptimal overall treatment efficacy. Thus, IORT has emerged as an effective procedure for local control of unresectable tumors or tumor remnants after resection of pancreatic cancer. Unlike external radiation therapy, IORT acts directly on the treatment site, can be delivered while sparing the surrounding organs and tissues, and can deliver a large radiation dose that provides ≥ 2 times the biological effect of separate radiation doses,[13] which shortens the overall treatment time.

Current domestic and international reports indicate that the Mobetron® system is the primary tool for performing IORT in cases of pancreatic cancer.[14] This system has a high electron beam energy and radiotherapeutic effects on local tumors in relatively deep locations (> 2 cm). Previous reports[15] have described its therapeutic effects on unresectable pancreatic cancers, although a relatively deep target combined with the high electron beam energy can lead to various adverse effects, such as gastrointestinal tract bleeding, bile duct fibrosis, biliary enteric anastomosis, peripheral nerve reactions, and other pancreas-associated complications. This approach can also have important effects on posterior organs and structures (for example, the vertebrae and spinal cord), which are considered major complications of IORT for pancreatic cancer. These effects include vertebral fracture, paraplegia, intraspinal hemorrhage, autonomic dysfunction, limb paralysis, and uncoordinated movement. Therefore, patients who undergo IORT for pancreatic cancer using the Mobetron system must accept a risk of developing severe radiotherapy-associated toxicities.

In the present case, we used the INTRABEAM system for IORT because it produces softer, shallower, and lower energy X-rays (30–50 kV) than the Mobetron system.[16–19] The INTRABEAM system also provides low penetration and rapid attenuation of the radiation dose,[18] which are improvements that have emerged from the evolution of minimally invasive surgery. There has been rapid clinical adoption of the INTRABEAM system in recent years, with good outcomes described in studies regarding breast-conserving surgery for breast cancer,[20,21] vertebral metastasis surgery,[22] and colorectal cancer surgery;[23,24] these good outcomes are attributed to the system's accuracy, minimally invasive nature, and low penetration depth. These characteristics allow the INTRABEAM system to protect important organs and tissues behind the pancreas and reduce the incidence of adverse effects that were associated with previous IORT systems. Moreover, given the low penetration depth, a relatively high radiation dose can be used at the clinical surface. For example, we used a radiation dose of approximately 10 Gy at the clinical surface; an effective irradiation intensity is achieved when the source applicator is < 5 mm from the target tissue. Thus, the INTRABEAM system is extremely practical for targeting residual tumor tissue after resection of pancreatic tumors. Previous studies have described doses of 10–30 Gy when the Mobetron system is used during IORT for pancreatic cancer,[25,26] although there is no established dose when using the INTRABEAM system. In the present case, we selected a relatively conservative dose of 10 Gy, and our patient did not develop any radiotherapy-related side effects, although further studies are needed to optimize the radiotherapy dose in similar cases.

The INTRABEAM system has a source applicator that comes in various shapes; this can facilitate personalized treatment based on the patient's tumor and target sites. In the present case, our surgical exploration revealed residual tumor tissue posterior to the pancreas; this residual tumor tissue invaded the retroperitoneal blood vessels, lymph nodes, and nerve plexuses. The upper boundary reached the trunk of the abdominal cavity, the lower boundary reached the middle colic artery starting from the superior mesenteric artery, and the right boundary reached the superior mesenteric artery. Because the tumor bed was relatively uniform, with no obvious compartmentalization, and had a rough surface, we selected a flatbed source applicator that was placed close to the tumor bed. The radiotherapy was performed after protecting the surrounding bowel, and our patient experienced a good postoperative course, with recovery of gastrointestinal function on postoperative day 2. Moreover, he was able to resume eating and was free from postoperative bleeding, infection, pancreatic leakage, and other complications; in addition, he had markedly relieved pancreatic cancer-related abdominal pain. Thus, he was discharged in good general condition on postoperative day 9.

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