Stereotactic Body Radiation Therapy (SBRT) for Unresectable Pancreatic Carcinoma

Current status of non-surgical treatment of locally advanced pancreatic cancer

Pancreatic cancer is the 7th leading cause of death due to cancer in industrialized countries and the 11th most common cancer globally, with 458918 new cases (2.5% of all cancers) and 432242 deaths (4.5% of all cancer deaths) in 2018. Unfortunately, 80% to 90% of the patients present with unresectable disease, and the reported 5-year survival rate range between 10% and 25%, even after successful resection with tumor-free margins. Systemic chemotherapy, radiotherapy, and minimally invasive image-guided procedures that have emerged over the past years, are used for the management of non-operable PC. This review focuses on currently available non-surgical options of locally advanced pancreatic cancer.

Volume de-escalation in radiation therapy: state of the art and new perspectives

PURPOSE

New RT techniques and data emerging from follow-up for several tumor sites suggest that treatment volume de-escalation may permit to minimize therapy-related side effects and/or obtain better clinical outcomes. Here, we summarize the main evidence about volume de-escalation in RT.

METHOD

The relevant literature from PubMed was reviewed in this article. The ClinicalTrials.gov database was searched for clinical trials related to the specific topic.

RESULTS

In Lymphoma, large-volume techniques (extended- and involved-field RT) are being successfully replaced by involved-site RT and involved-node RT. In head and neck carcinoma, spare a part of elective neck is controversial. In early breast cancer, partial breast irradiation has been established as a treatment option in low-risk patients. In pancreatic cancer stereotactic body radiotherapy may be used to dose escalation. Stereotactic radiosurgery should be the treatment choice for patients with oligometastatic brain disease and a life expectancy of more than 3 months, and it should be considered an alternative to WBRT for patients with multiple brain metastases.

CONCLUSION

Further clinical trials are necessary to improve the identification of suitable patient cohorts and the extent of possible volume de-escalation that does not compromise tumor control.

Current and emerging radiotherapy strategies for pancreatic adenocarcinoma: stereotactic, intensity modulated and particle radiotherapy

The role of radiotherapy for locally advanced pancreatic cancer (LAPC) is unclear based on studies that used conventional doses and fractionation schedules. Modern radiotherapy techniques have not been studied in depth, however. We reviewed the literature on emerging methods of delivering higher doses of conformal radiotherapy using stereotactic body radiation, intensity modulated radiation, and particle beam radiation, highlighting clinical outcomes and toxicities. The literature review suggests low rates of acute and late toxicities when higher doses of radiation are given with careful attention to normal tissue dose constraints, including for stereotactic body radiotherapy (SBRT), escalated doses with intensity modulated radiation therapy (IMRT), and particle-based therapy. Retrospective evidence suggests prolonged survival for patients who receive biological equivalent doses above 70 Gy. Prospective trials that evaluate modern radiotherapy techniques are warranted for LAPC.

Stereotactic Radiotherapy and Particle Therapy for Pancreatic Cancer

Pancreatic cancer is a devastating disease with poor survival outcomes. Recent studies have shown that the addition of radiotherapy to chemotherapy in the setting of locally advanced pancreatic cancer did not improve overall survival outcome. These studies commonly utilize conventional radiotherapy treatment fractionation and technique (typically 3-D conformal radiotherapy or intensity modulated radiotherapy). Although no clear benefit in overall survival was demonstrated in those studies, those who received radiotherapy did have a clear benefit in terms of local control. Therefore, there is increasing interest in exploring different techniques and/or modality of radiotherapy and dose/fractionation. Stereotactic radiotherapy, which employs a hypofractionated regimen, has the potential advantage of delivering a high dose of radiation to the tumor in a short period of time (typically over 5 days) with minimal dose to the surrounding normal structures. Particle therapy such as proton and carbon ion therapy are being explored as potential radiation modality that could cause greater biological damage to the tumor compared to photon treatment, with rapid dose falloff resulting in minimal to no dose to adjacent structures. This review will discuss the current literature and emerging roles of stereotactic radiotherapy and particle therapy in pancreatic cancer.

Duodenal invasion by pancreatic adenocarcinoma: MDCT diagnosis of an aggressive imaging phenotype and its clinical implications

Despite advances in oncologic and imaging technology, pancreatic ductal adenocarcinoma remains a highly deadly disease. The only curative option, pancreaticoduodenectomy or pancreatectomy, carries a significant morbidity. Current imaging plays a role in pre-operative staging to determine the probability of achieve disease-free margins. However, a small but not insignificant number of pancreatic cancers have a relatively higher aggressive biology, despite being resectable based on traditional criteria. Recently, imaging biomarkers that serve as a surrogate for tumors with such aggressive phenotype have been described. These include duodenal invasion and extrapancreatic perineural invasion. This review will focus on the former highlighting the summary of literature supporting duodenal invasion as a surrogate for aggressive disease as well as review its MDCT imaging features.