EXTENDING QUALITY IMPROVEMENT FOR PANCREATODUODENECTOMY WITHIN THE HIGH-VOLUME SETTING: THE EXPERIENCE FACTOR

Introduction
The role of lymph node (LN) parameters in pancreatoduodenectomy (PD) for cancer has been mainly investigated in the upfront surgery setting. Yet, due to the impact of neoadjuvant therapy (NAT) on nodal status, these results cannot be directly translated to post-NAT PD. This study aimed to examine LN yields and metastases per anatomical stations and how the extension of LN dissection affects nodal staging in post-NAT PD. Lastly, the prognostic role of LN parameters was investigated.
Methods
An institutional lymphadenectomy protocol was prospectively applied to all post-NAT PDs from June 2013. Lymphadenectomy included stations 5/6/8a-p/12a-b-c-p/13/14a-b/17 and jejunal mesentery LNs. Stations embedded in the PD specimen (13/14/17/jejunal) were defined as first-echelon, those sampled separately (5/6/8/12) as second-echelon. The prognostic impact of LN parameters in N+ patients was evaluated using uni- and multivariable Cox regression. To avoid collinearity, separate multivariable models were designed for each nodal parameter.
Results
Among 288 patients 61% received FOLFIRINOX, 30% Gem-Abraxane. The median number of examined (ELN) and positive LNs (PLN) were 43 and 1, and 185 patients were N+ (64%). The commonest metastatic sites were stations 13 (51%), 14 (34%) and 17 (32%). The overall rates of first and second echelon involvement were 60% and 20%. The median number of ELN and PLN in the first echelon were 29 and 1. The addition of second echelon LNs increased nodal counts by 9 ELN and 0 PLN, resulting in only minor changes in staging.
The median follow-up was 25.1 months, 35.8 in censored cases. At multivariable analysis, second echelon involvement, ≥4 metastatic stations, metastases to station 8 and jejunal mesentery LNs, but not N2 status, were independently associated with survival of N+ patients, along with adjuvant treatment.
The median recurrence-free survival (RFS) was 14.8 months and 176 patients experienced recurrence (71%), among which 41 were local relapses (23%). In N+ patients, nodal echelons, ≥4 metastatic stations and tumor involvement of station 8,14 and jejunal mesentery LNs were independent predictors of RFS, along with Ca 19.9 response, T- and R-status and adjuvant treatment. Distant recurrences incrementally increased with nodal involvement (Figure).
Conclusion
LN metastases most commonly occur in first-echelon LNs, and first-echelon dissection provides an adequate number of ELN for optimal staging. Examining second-echelon LNs does not improve the staging process substantially. Yet, second-echelon involvement is prognostically relevant, as well as metastases to station 8 and jejunal mesentery LNs. These data have potential implications when assessing surgical indication after NAT. Moreover, intraoperative frozen section of station 8 might help decision-making, especially in technically demanding cases or fragile patients.

Background:
The concept of “experience” in surgery remains nebulous and multifactorial, encompassing both the surgeon and the institution as pivotal variables. While a surgeon’s career volume seems to be a determinant in improving outcomes for pancreatoduodenectomy (PD), the influence of individual surgeon experience within high-volume institutional settings remains undefined. Within such a framework, the present investigation analyzes the association of cumulative surgeon volume experience with risk-adjusted postoperative outcomes after PDs.

Methods:
A total of 8,189 PDs performed by 82 surgeons at 18 international institutions (median:140 PD/year) were accrued from 2003 to 2020. Surgeon’s cumulative PD volume was categorized in 4 quartiles (≤150, 151 to 285, 286 to 525 and ≥526 PDs). Associations of categorical and continuous variables were analyzed with appropriate univariate tests. Fistula Risk Score (FRS)-stratified performance comparisons of postoperative outcomes across each volume quartile were quantified through multivariable analyses. Next, the same methodology was implemented when considering the ten most impactful scenarios (previously defined as a combination of occurrence and severity) for the development of clinically relevant pancreatic fistula (CR-POPF; n = 2,830 patients).

Results:
Within the overall cohort, 18.7% patients suffered severe complications (Accordion≥3), 14% developed CR-POPF, 4.8% were reoperated upon, and 2.2% expired. Surgeons performed a median of 68.5 career PDs (IQR 21-136), with a median FRS of 4 (IQR 3-5). When compared with those with less experience, the top-quartile surgeons more often operated on intermediate/high FRS cases (73% vs 61%, p <0.001); yet, their performance was associated with significant declines in CR-POPF, severe complications, reoperations, and length of stay (8 vs 9 d), whereas mortality and failure-to-rescue were not affected (Figure). This same outcome profile was accentuated even more when considering the most frequent and impactful FRS scenarios that surgeon encounter. In the overall cohort, risk-adjusted models indicate male gender, increasing age, ASA class and FRS, but not surgeon experience, as predictors for severe complications, failure-to-rescue and mortality. Instead, in advanced fistula risk circumstances, upper-echelon experience demonstrates significant reductions in CR-POPF, reoperations and LOS (Table).

Conclusion:
At specialty institutions, mortality and failure-to-rescue depend primarily on baseline patient and systemic characteristics, while cumulative surgical experience independently impacts pancreatic fistula occurrence and its attendant effects - even more so for riskier PDs. These data suggest an extended learning curve exists for this operation and reinforce the notion that surgeon experience is a key contributor for outcome improvement.