**1. Introduction**

By 2030 pancreatic cancer (PaC) is expected to be the second cancer-related cause of death [1]. Its 5-year survival in nonmetastatic stages currently ranges between 3 and 14% [2] regardless of treatment. Surgery remains the only chance for cure since the 5-year survival in T1 N0 resected patients reaches 55.2% [3]; therefore, the standard of care advocates a surgery-first approach in case of resectable disease followed by adjuvant treatment (ADT), but neoadjuvant approaches are spreading either in resectable or borderline resectable (BLR) and locally advanced (LA) patients. The National Comprehensive Cancer Network (NCCN) states that there is limited evidence to recommend specific neoadjuvant regimens off-study [4]. While the only choice in LA PaC is a locoregional chemoradiation (CRT) or systemic chemotherapy (CHT) and subsequent revaluation, for resectable and BLR, we must choose between a surgery-first approach and a neoadjuvant treatment (NADT). Over 40% of patients who have clinically a resectable disease are found unresectable at surgery, even though this percentage drops to 20% if a diagnostic laparoscopy is added to the preoperative diagnostic panel [5]; one out of five patients are eventually misdiagnosed as resectable or BLR while having a LA disease. Even in a high-volume referral hospital, the percentage of successfully resected patients at surgical exploration is as low as 51% [6]. Results of first-line pancreatectomy may be very poor with only 20% of patients receiving radical surgery and 80% presenting tumor within 1 mm from margin or direct microscopic margin infiltration [7]. In a Korean series, 9.1% of patients presenting with PaC diagnosis were clinically staged as BLR [8], about 27% of whom required a vascular resection (VR) in order to achieve their pancreatectomy [9], but histological invasion of resected vessels is confirmed only in 56.7% of specimens [10]. Finally, up to 28% of successfully resected patients will not undergo ADT because of surgical morbidity, poor performance status, refusal, or early recurrence [10]. As Buchler said, unfortunately available evidences supporting NADT come from retrospective studies in which treatment protocols vary greatly and patient cohorts are often mixed with resectable, BLR, and LA [11].

Whereas features of a metastatic disease are evident, dealing with PaC and NADT, a foreword has to be spent to clarify the terminology "resectable," "borderline resectable," and "locally advanced." To that end, we will first focus on the definition of borderline resectable disease and then analyze the outcomes of NADT from a surgical point of view.

With the PV/SMV-SMA plane being its bed and the celiac trunk being its roof, resectability and thus possibility of cure are played in few millimeters. As shown in **Figure 1**, PaC may arise in the head, body, or tail of the pancreas; therefore, respectability definition differs along with its location whether on the right of the left border of PV/SMV (head) or on the left of the left aortic border (tail) or in between (body). In surgery few things are technically impossible; this is heavily surgeon-dependent because it relies in its skills and will. That is why several institutions/associations have tried and classified PaC resectability depending on its involvement of nearby structures. In **Table 1** the anatomic criteria for definitions of borderline resectable disease from the classifications of five major institutions are shown: MD Anderson Cancer Center [9], American Hepato-Biliary-Pancreatic Association/Society of Surgery of the Alimentary Tract/Society of Surgical Oncology (AHBPA/SSAT/SSO) [13], Alliance A021101 [14], IAP [3], and NCCN [4]. Any situation with a more extensive vascular involvement will obviously be classified under the "locally advanced/unresectable" definition, whereas a less extensive one will define a resectable disease. Despite the effort to standardize definitions and make patients and features comparable among radiologist and surgeons, in some classifications, terms like "allowing for safe reconstruction" still appear increasing confusion among professionals and trials. It is interesting how some may consider a unique SMV/PV <180° involvement that implies a venous resection, as a resectable disease, whereas an arterial involvement is always considered at least borderline resectable; this is due to the surgical

artery; GDA, gastro-duodenal artery.

**Figure 1.** Schematic representation of pancreatic vascular relationships. AA, Aorta; IVC, inferior vena cava; PHA, proper hepatic artery; PV, portal vein; SMV, superior mesenteric vein; SMA, superior mesenteric artery; IMV, inferior mesenteric vein; SV, splenic vein; SA, splenic artery; LGA, left gastric artery; CA, celiac axis; CHA, common hepatic

The Role of Neoadjuvant Therapy in Surgical Treatment of Pancreatic Cancer

http://dx.doi.org/10.5772/intechopen.76750

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