Stereotactic body radiation therapy for pancreatic cancer: a potential ally in the era of immunotherapy?

Abstract

of PC were expected to occur, and PC was ranked as the ninth leading primary site among the major cancers in Korea [1]. The incidence rates of PC have been on the rise and are predicted to increase over the next several decades, and PC is expected to be the fourth most common cause of cancer-related deaths by 2022 in Korea [1,2]. Curative surgical resection is the only chance for long-term survival; however, surgical resection is often limited due to many people being diagnosed at an advanced stage and the proximity of the pancreas to major vessels that cannot be replaced or removed. Although the role of radiotherapy (RT) in PC has been controversial, it has been consistently proven that RT has a proven effect in controlling local disease [3,4]. Previous studies on PC showed that there were high rates of local recurrence or progression that led to the development of pain, gastrointestinal obstruction, bleeding, and other morbidities associated with the primary disease site, impairing the quality of life with chemotherapy and/or surgery alone [3,5]. Therefore, improving local control remains an important aim of RT in patients with PC, regardless of distant disease control. Moreover, RT has become an important modality by better systemic control with an improved chemotherapeutic regimen, and modern radiotherapy techniques with high-precision help local control in a multimodal setting with an acceptable side effect. Stereotactic body radiotherapy (SBRT) is a modern RT technique that has various benefits compared with conventional RT and has been widely applied as a local therapy for the treatment of several types of malignancies [6]. SBRT enables conformal delivery of high radiation during a short period with reduced irradiation to surrounding normal tissues over conventional RT, and SBRT is considered to have different tumoricidal mechanisms [7,8]. SBRT for PC has been vigorously applied during the last decade for definitive or neoadjuvant aims due to the short treatment duration with limited acute toxicity, which is less disruptive to effective systemic treatment than chemoradiation therapy (CRT) [9]. A previous study that compared conventional CRT with SBRT showed that SBRT could be a feasible alternative to CRT for the treatment of PC [10]. In addition to these advantages of SBRT, it is worth noting that SBRT could promote antitumor immune response through various mechanisms, which could not be expected from conventional CRT [11-13]. However, because SBRT or immune checkpoint inhibitors (ICIs) alone is not sufficient to induce an effective immune response in PC, it could be a novel strategy to combine ICIs with SBRT to overcome resistance to immunotherapy, which means a shift from this “cold tumor” to “hot tumor” [8,13-15]. In the current study to be mentioned in this editorial, Reddy et al. [16] analyzed 68 paStereotactic body radiation therapy for pancreatic cancer: a potential ally in the era of immunotherapy?