Stereotactic PAncreatic RadioTherapy Adjuvant Therapy

Overview

While surgery is considered the only potentially curative therapy for pancreatic cancer, 5-year overall survival (OS) is typically \<25%. Following surgical resection of pancreatic cancer, adjuvant conventionally fractionated RT (CRT, delivering 45-54 Gy in 1.8-2.0 Gy per fraction) with 5-FU chemotherapy is recommended in high-risk patients (positive lymph nodes and/or R1-R2 resection margin status). However, the benefit of CRT in this setting is controversial due to lack of prospective positive data. Moreover, duration of treatment course (delaying initiation of more effective chemotherapy schedules), insufficient dose delivery due potential radiation-related severe toxicity to proximity organs represents a serious limitation to treatment efficacy. Stereotactic Body Radiotherapy (SBRT) is a novel radiotherapy technique consisting of highly focused irradiation with a steep dose gradient, thus allowing the delivery of ablative radiation doses and significant sparing of proximity critical structures. Higher doses per fraction allows for more intensive treatments and shorter duration of the radiation course.

Pancreatic carcinoma is expected to become in the next 10 years the second leading cause of cancer-related mortality. Resection is the only treatment with the potential to achieve long-term survival, although expected survival at 5 year is \<25%: postoperative use of local and systemic adjuvant treatments has been proposed to improve outcome While the efficacy of adjuvant chemotherapy, in parrticular multiagent chemotherapy, has been established, the potential impact of chemoradiation in the adjuvant setting is still controversial. However, its use in patients with high risk features such as nodal involvement and close or positive margins may be of interest. Adjuvant chemoradiation, when clinically indicated, is usually delivered in a 6 week treatment course in association with concurrent dose-adapted chemotherapy, implying the necessity to interrupt more effective multi-agent chemotherapy schedules due to risk of increased toxicity. It has been proposed that higher radiotherapy doses may result in improved outcome although a potential detrimental effect on survival of dose escalation \>55 Gy with conventional fractionation, possibly related to increased toxicity, has been reported. Stereotactic Body Radiotherapy (SBRT) is a novel radiotherapy technique consisting of highly focused irradiation with a steep dose gradient, thus allowing the delivery of ablative radiation doses and significant sparing of proximity critical structures. Higher doses per fraction allows for more intensive treatments and shorter duration of the radiation course. In a retrospective study by Rwigema et al, adjuvant pancreatic SBRT was shown to be a safe and feasible treatment option for patients with high-risk pancreatic adenocarcinoma.