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Page 2 of 8 Puckett et al. J Cancer Metastasis Treat 2020;6:11 I http://dx.doi.org/10.20517/2394-4722.2020.98

Figure 1. Sixty-six year-old man diagnosed with: biopsy-proven PDAC seen on CT (A); the patient also had synchronous biopsy-proven
liver metastases (B and C, red arrows); he underwent neoadjuvant chemotherapy with 5-FU, leucovorin, oxaliplatin, and irinotecan with
radiologic response 24 months after diagnosis (D-F). Surgical resection of the pancreas and liver lesions was performed as a one-stage
[7]
procedure. The patient remained disease-free 30 months post-resection . PDAC: pancreatic ductal adenocarcinoma; CT: computed
tomography; 5-FU: 5-fluorouracil

[1,2]
35 years . The majority of PDAC is diagnosed when the cancer has spread to distant sites or has become
[3,4]
unresectable . The term oligometastastases, coined in 1995 by Hellman and Weichselbaum, refers to
[5]
[6]
the existence of metastases that are few in number . In 2019, Damanakis et al. proposed a definition
for oligometastatic disease in pancreatic cancer that included anatomic as well as biological criteria to
identify a subset of patients with favorable biology and improved prognosis who may be candidates for
surgery. Damanakis restricted the cohort to patients with “limited disease,” defined as 4 or fewer hepatic or
pulmonary metastatic lesions, as well as only individuals with a Carbohydrate antigen 19-9 (CA 19-9) of less
than 1,000 U/mol. In addition, only patients who responded to systemic chemotherapy were included. With
these restricted criteria, the investigators identified a subset of about 8% of patients from the original cohort
with metastatic disease who had improved overall survival with resection.

Traditionally, oligometastatic disease in the context of PDAC has been associated with a poor prognosis with
[7]
an average life expectancy of approximately 6 months and a median 5-year overall survival of 1% . Surgical
resection of oligometastatic disease in pancreatic cancer is generally not associated with prolonged survival.
The National Comprehensive Cancer Network treatment guidelines do not, therefore, consider these patients
[8]
to be surgical candidates . However, the topic has been much debated, and some centers have performed
resection of PDAC metastases and have published data advocating for this approach in very select patients
[Figure 1] [5,8-10] .

A review on resection of PDAC metastasis published in 2006 reported a median survival ranging from 4 to 6
[4]
months with a 5-year survival of zero . Nevertheless, potential utility of resecting oligometastatic disease has
been suggested based on outcomes after palliative R2 resection. For example, a study by Bockhorn et al.
[11]
demonstrated a survival benefit for patients who underwent an R2 resection versus versus bypassed patients
(11.5 vs. 7.5 months). However, patients who underwent an resection experienced increased morbidity such
as longer hospital stay, and 2 patients out of 40 died perioperatively. These data suggested that debulking of