The gastrectomy site might affect the rate of occurrence of DGE and survival of cancer patients; however, there is no data on the gastrectomy site. At what distance is the gastrectomy performed from the pylorus ring? How much stomach is remnant? All of the four RCTs demonstrated that the incidence of DGE in PPPD was similar to that in PD [11–13]. If only extended gastrectomy patients were included in those studies, those RCTs might demonstrate other results. Kawai et al. reported the result of an RCT focused on the pylorus ring, PPPD versus pylorus-resecting PD (PRPD), with near total stomach preservation. They gave it the name of pylorus-resecting PD (PRPD) and proposed this as a new procedure [17]. It was determined that the incidence of DGE was 4.5% in PRPD and 17.2% in PPPD, with a significant difference. This RCT is an epoch to determine whether the pylorus ring affects the occurrence of DGE or not, and it revealed that the pylorus ring is the deciding factor in the occurrence of DGE.

Japanese surgeons have previously performed SSPPD, which is PD combined with an intended antrectomy; however, SSPPD does not clearly define the gastrectomy site [18]. A meta-analysis demonstrated that the occurrence of DGE favors SSPPD compared to PPPD (odds ratio 2.75, 95% CI 1.75–4.30, P < 0.00001) [19]. However, PRPD was included in the SSPPD group in this meta-analysis. Distal gastrectomy in PD is associated with gastric emptying via gastroenteric hormones [20], and the RCT (PPPD vs. PRPD) has clarified the importance of the antrum [20]; therefore, the concept of PRPD is different from that of SSPPD.

Reconstruction route was previously thought to be important in the occurrence of DGE. Two reconstruction routes are usually considered for duodenojejunostomy, the antecolic route or the retrocolic route in PPPD. However, Tani et al. paid attention to the reconstruction, and an RCT was conducted to analyze whether or not an antecolic route reduces the incidence of DGE compared to a retrocolic route. DGE occurred in 5% of patients with the antecolic route for duodenojejunostomy versus 50% with the retrocolic route (P = 0.0014). Those with the antecolic route had a significantly shorter duration of postoperative nasogastric tube drainage than did those with the retrocolic route (4.2 days versus 18.9 days, respectively, P = 0.047). This result demonstrated the superiority of the antecolic route in prevention of DGE by interim analysis [21]. Therefore, this RCT investigated a small cohort of patients, although this RCT was statistically planned for 140 patients. Table 31.2 shows the summary of RCTs focused on only PPPD assigned into two groups: antecolic reconstruction and retrocolic reconstruction.