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SURGEON-LEVEL VARIATION IN UTILIZATION OF NEOADJUVANT THERAPY FOR LOCALLY ADVANCED RECTAL ADENOCARCINOMA
Douglas S. Swords*2,1, David E. Skarda2,1, William T. Sause3, Ute Gawlick2, George M. Cannon3, Mark A. Lewis3, Jesse Gygi3, H T. Kim2
1Surgery, University of Utah, Salt Lake City, UT; 2Surgical Services Clinical Program, Intermountain Healthcare, Salt Lake City, UT; 3Oncology Services Clinical Program, Intermountain Healthcare, Salt Lake City, UT

Background: Neoadjuvant therapy for clinical stage II-III rectal adenocarcinoma has been standard of care for over a decade, and delivery of preoperative chemoradiation to such patients is a Commission on Cancer quality metric. National Cancer Database studies have shown that only 75% of appropriate patients receive neoadjuvant therapy, but the determinants of this failure to deliver evidence-based therapy remain largely unknown. We aimed to determine the underlying reasons for omission of neoadjuvant therapy using granular clinical data from a 22-hospital system.

Methods: This is a retrospective study of patients with clinical or pathologic stage II-III rectal adenocarcinoma treated with initial curative intent from 2010-2016 in an Intermountain Healthcare hospital. Patients who were stage I by endoscopic ultrasound or MRI who were upstaged to pathologic stage II-III at surgery were excluded (N=12). Covariates with a univariate P<0.2 were included in a multivariable logistic regression model for predictors of omission of neoadjuvant therapy. Risk ratios and adjusted risk differences were obtained using marginal standardization. Risk- and reliability-adjusted rates of neoadjuvant therapy were calculated for surgeons who treated ≥3 patients. Rates of positive margins (positive proximal/distal margin or circumferential radial margin ≤ 1 mm) and long-term outcomes were examined after excluding patients who were not resected(N=4) or who underwent local excision(N=6).

Results: There were 240 patients with clinical stage II-III or undocumented clinical stage/pathologic stage II-III rectal cancer who were treated by 36 surgeons at 9 hospitals. Three surgeons treated 122/240 patients (50.8%). Neoadjuvant therapy was omitted in 41/240 (17.1%). Processes of care in which neoadjuvant therapy was omitted and independent predictors of omission of neoadjuvant therapy are shown in the Table. Among 21 surgeons who treated ≥ 3 cases, adjusted rates of neoadjuvant therapy varied 3.5-fold (28% to 97%, Figure A). Rates of positive margins were higher in patients who did not receive neoadjuvant therapy: 8/40 (20.0%) vs. 16/190 (8.4%) (P=0.03, chi-square). Neoadjuvant therapy was associated with lower rates of local recurrences (P=0.0175, log-rank, Figure B) but no differences in rates of distant metastases, disease-specific survival, or overall survival (P>0.26 for all, log-rank, not shown).

Conclusions: The dominant risk factors for omission of neoadjuvant therapy are tumor location in the upper rectum and treatment by a low volume surgeon. Surgeon rates of neoadjuvant therapy varied 3.5-fold, and low volume surgeons utilized neoadjuvant therapy less often. Neoadjuvant therapy was associated with lower rates of positive margins and local recurrences. Initiatives that give low-utilizing surgeons feedback about appropriate utilization of neoadjuvant therapy are warranted.

Processes of Care and Factors Associated with Omission of Neoadjuvant Therapy
Processes of Care in Patients Where Neoadjuvant Therapy was Omitted (N=41)
Process of CareN (%)
Taken directly to surgery without EUS or MRI19(46.3%)
Thought to be sigmoid cancer preoperatively11 (26.8%)
"Urgent" presentation (obstruction, substantial bleeding, or perforation)4 (9.8%)
Upfront surgery even though cT3-T4 and/or cN1 on EUS or MRI3 (7.3%)
Concerns about functional status2 (4.9%)
Synchronous colon cancer1 (2.4%)
Tumor not thought to be an invasive cancer preoperatively1 (2.4%)
Multivariable Analysis of Factors Associated with Omission of Neoadjuvant Therapy
 Risk Ratio
(95% CI)
Adjusted Absolute Risk Difference
(95% CI)
P
Female sex (vs. male)1.78 (1.11, 2.87)9.4 (3.1, 15.7)0.003
Cancer history (vs. none)2.31 (1.26, 4.22)19.9 (1.7, 38.1)0.03
Location (vs. ≤ 6 cm from anal verge)   
6.01-12 cm1.70 (0.75, 3.86)6.7 (-4.9, 18.30.26
> 12 cm4.35 (2.67, 7.09)32.1 (20.8, 43.3)<0.001
Urgent presentation1.86 (0.90, 3.84)13.9 (-8.6, 36.4)0.22
Colorectal surgeon0.91 (0.49, 1.66)-1.6 (-11.6, 8.3)0.75
Surgeon volume (vs. > 3 cases/year)   
≤ 3 cases/year9.45 (2.78, 32.06)25.1 (14.0, 36.2)<0.001


Risk- and reliability adjusted rates of neoadjuvant therapy among surgeons that treated ≥ 3 patients (A) and cummulative probability of local recurrences (B)


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