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Page 4 of 9 Makuuchi et al. J Cancer Metastasis Treat 2018;4:26 I http://dx.doi.org/10.20517/2394-4722.2018.15
[14]
death. Nunobe et al. featured the largest number of patients, including 31 patients with gastric cancer who
underwent PD. Although their center is one of the largest high-volume centers in Japan, with > 300 cases of
gastrectomy performed during one year, the mortality rate of PD was as high as 13%. The most frequently
observed complication was pancreatic leakage (13%), followed by intraabdominal abscess (6%) and colitis (6%);
however, they did not report the rates of the other postoperative complications.

In our center, 24 gastric cancer patients underwent PD from 2002 to 2016; 19 patients underwent distal
gastrectomy and 5 patients underwent total gastrectomy. Differentiated adenocarcinoma was noted in 15
patients and undifferentiated adenocarcinoma was noted in nine. The median blood loss was 1218 mL and
the median operative time was 449 min. R0 resection was performed on 17 patients (70.8%) and R1 was
performed on 7 patients (29.2%) owing to positive lavage cytology (CY1). There were no patients with tumor-
positive resection margins. Four patients had a small number of peritoneal deposits adjacent to the stomach,
which were completely resected during operation.

SURVIVAL BENEFITS OF PD FOR PATIENTS WITH GASTRIC CANCER
Several studies have evaluated the survival outcomes of patients undergoing PD for gastric cancer [Table 1].
However, conflicting results were reported, mainly because of heterogeneous data and small sample size in
each study.

According to studies that evaluated multivisceral resection for gastric cancer clinically invading the
adjacent organs (T4b) or for pathologic T4b gastric cancer, R0 resection and lymph node status were the
independent prognostic factors [3,4,6,19] ; however, few studies have shown poor survival outcomes for patients
who underwent combined resection of the pancreas or a tumor invading the pancreas [16,20] . It is important
to note that, in these studies, the number of patients who underwent PD was few or unknown. Among
[16]
these, the retrospective study on the prognostic factors in patients with T4b gastric cancer by Min et al.
reported the highest number of patients who underwent PD; there were a total of 243 T4b gastric cancer
patients, including 67 patients that had tumor invasion to the pancreas. In that study, pancreatic invasion
was identified as an independent unfavorable prognostic factor by multivariate analysis. Moreover, among
the operation methods used for pancreatectomy in the pancreatic invasion group, the PD group (n = 9) had a
significantly lower 5-year survival rate, compared with that of the other pancreatectomies group (n = 58) (0%
vs. 27.4%, P = 0.013). Therefore, they did not recommend PD for T4b gastric cancer invading the pancreatic
head.

In contrast, studies that compared PD and gastrectomy alone for T4b gastric cancer have found a therapeutic
[15]
benefit of PD. Wang et al. evaluated 53 patients with gastric cancer and pancreaticoduodenal region
involvement and found that PD improved the 3-year survival rate, compared with that of palliative
[9]
gastrectomy (34% vs. 5.6%, P = 0.0064). Hirose et al. showed that among patients with gastric cancer
invading the pancreatic head, the median survival time (MST) was better in the PD group than in the
[8]
palliative gastrectomy group (19 months vs. 9 months, P = 0.0478). Yonemura et al. also demonstrated
that, compared with gastrectomy alone, PD with right hemicolectomy improved the 5-year survival rate of
[11]
patients with pancreatic invasion (55% vs. 0%, P <0.01). Saka et al. investigated 23 patients who underwent
R0 resection with PD for gastric cancer macroscopically infiltrating the pancreatic head and showed that the
5-year survival rate was significantly better in patients without incurable factors, such as para-aortic lymph
node metastasis, positive lavage cytology (CY1), and peritoneal dissemination, than in those with incurable
factors (47.4% vs. 0%, P = 0.035). It should be noted that in that study, CY1 cases were treated as R0 resection,
which is considered an R1 resection according to the 7th edition UICC TNM classification.

In patients undergoing PD, there are two patterns of invasion to the pancreatic head, including direct
invasion of the primary tumor and invasion via metastatic lymph nodes. Although most studies have not
[14]
investigated survival according to the pattern of pancreatic invasion, the study by Nunobe et al. showed