Background: Capecitabine and oxaliplatin (CAPOX) and infusional 5-fluouracil, folinic acid, and oxaliplatin (FOLFOX) are the two chemotherapy regimens in current clinical use for the adjuvant treatment of colorectal cancer (CRC). Many centers in Newfoundland lack the resources to support the home infusion program required for FOLFOX, leaving CAPOX as the sole treatment option. This study aimed to review if Newfoundland patients receiving CAPOX experience greater treatment-induced toxicities. Methods: A multicenter retrospective cohort study of 93 Stage III CRC patients. The frequency and severity of toxicities, healthcare resource utilization, and treatment completion rates were compared between the two treatment options. Results: Grade 3 diarrhea and grade 1 or 2 nausea/vomiting were more common in CAPOX compared to FOLFOX-treated patients (26.9% versus 2.99%, p = 0.002; 61.5% versus 31.8%; p = 0.048, respectively). Grade 1 or 2 mucositis was more common with FOLFOX (35.8% versus 3.9%, p = 0.002). CAPOX was associated with higher rates of severe toxicity (53.9% versus 25.4%, p = 0.009), while rates of grade 1 and 2 toxicities were not significantly different between groups. CAPOX-treated patients were greater than twice as likely to require emergency department treatment secondary to toxicity (mean 0.692 visits per patient versus 0.313 in FOLFOX patients, p < 0.001) and the proportion of patients that were hospitalized secondary to CAPOX toxicity was greater. Significantly more FOLFOX patients were able to finish their prescribed treatment plans compared to CAPOX patients (89.5% versus 53.8%; p < 0.001). Conclusions: Compared to FOLFOX-treated patients, CAPOX patients are more likely to experience toxicities of greater severity, require emergency services secondary to treatment-related toxicity, and to discontinue therapy. This reflects a reduced standard of care that may decrease patient safety and quality of life.

The annual Eastern Canadian Gastrointestinal Cancer Consensus Conference 2023 was held in Quebec City, Quebec 2–4 February 2023. The purpose of the conference was to develop consensus statements on emerging and evolving treatment paradigms. Participants included Canadian medical oncologists, radiation oncologists, pathologists and surgical oncologists from across Ontario, Quebec, and the Atlantic provinces. Consensus statements were developed following rapid review presentations and discussion of available literature. The recommendations proposed here represent the consensus opinions of physicians involved in the care of patients with gastrointestinal malignancies who participated in this meeting.

476 Background: FOLFIRINOX (FFX), gemcitabine plus nab-paclitaxel (GN), and gemcitabine (gem) are 3 publicly funded and available treatment options for locally advanced (LAPC) and metastatic pancreatic cancer (MPC) in Canada since 2014. Without head-to-head trials that directly compare all 3 regimens, treatment selection and outcomes in 1L and 2L remain poorly characterized in routine clinical practice. Methods: Data from 4 tertiary, 8 regional, and 28 community hospitals in Canada were pooled. LAPC and MPC patients diagnosed from 2014 onwards and who received at least 1 line of systemic therapy were included. Analyses were conducted to identify predictors of treatment choice and to determine the relationship between treatment patterns and overall survival (OS) from APC diagnosis to death. Results: We identified 279 eligible patients. Median age was 64 (IQR 56-69) years, 55% were men, and 46% were ECOG ≥2. There were 27% LAPC and 73% MPC. In the 1L setting, FFX and GN were given in 44% and 41% of patients, respectively, and gem in 15%. GN was the preferred multi-agent therapy in worse ECOG patients (66% in ECOG 2+ vs 21% in ECOG 0, p = .001) and in more recently diagnosed cases (63% in 2016 vs 25% in 2014, p = .001). 1L treatment selection was not influenced by other baseline characteristics, such as age, sex, tumor location, or LAPC vs MPC status (all p > 0.05). A total of 91 patients proceeded to subsequent therapies, of whom 55 (60%), 27 (30%), and 9 (10%) had received 1L FFX, GN, and gem, respectively. In the 2L setting, GN after 1L FFX (41/55; 75%) and fluoropyrimidine (FP) after 1L GN (21/27; 78%) were the most common sequential approaches. Patients who underwent 2L therapy had better OS than those who did not (13 vs 7 months, p = .001). After adjusting for confounders, receipt of 1L FFX plus 2L GN or 1L GN plus 2L FP resulted in improved OS when compared to other treatment sequences (HR 0.43, 95%CI 0.28-0.67, p = 0.001 and HR 0.57, 95%CI 0.39-0.83, p = 0.004, respectively). Conclusions: One third of APC patients receive 2L therapy, highlighting the feasibility of 2L trials. Use of 1L multi-agent therapy followed by 2L non-cross-resistant regimens represents a reasonable treatment strategy for APC in the real world.

397 Background: Pathologic complete response (pCR) to neoadjuvant chemoradiation (CRT) for rectal cancer is associated with better long-term outcomes, and is used as an early indicator of response to novel agents. To assess the rate and predictors of pCR, we performed a retrospective population based study in four Canadian provinces. Methods: Cancer Registries identified consecutive patients with clinical stage I-III rectal cancer from the Tom Baker Cancer Center, Cross Cancer Institute, BC Cancer Agency, Ottawa Hospital Cancer Centre and the Dr. H. Bliss Murphy Cancer Centre who received fluoropyrimidine-based CRT and had curative intent surgery (Sx) from 2005 to 2012. Patient, tumor, and therapy characteristics were correlated with response. Results: Of the 891 patients included, 885 patients had pCR data available. 161 (18.2%) had a pCR to CRT, while 724 (81.8%) did not. Patients with a pCR had a lower pre-treatment (tx) CEA, and higher hemoglobin on univariate analysis (see table). On multivariable analysis, statin use at baseline (OR 1.7, 95% CI 1.04-2.89, p=0.044), lower pre-tx CEA (OR 1.03, 95% CI 1.003-1.05 p=0.028) and distance closer to anal verge (OR 1.07, 95% CI 1.004-1.15, p=0.039) were significant predictors of pCR. The 3yr DFS was 86% in those with pCR vs 62.5% in those without a pCR (P

580 Background: Neoadjuvant chemoradiation (CRT) is the standard of care for patients with locally advanced rectal cancer. Many patients require dose reduction or chemotherapy interruption due to significant toxicities. To assess the predictors of neoadjuvant chemotherapy treatment (tx) adjustments, we performed a retrospective study in four Canadian provinces. Methods: Cancer Registries identified consecutive patients with clinical stage I-III rectal cancer from the Tom Baker Cancer Center, Cross Cancer Institute, BC Cancer Agency, Ottawa Hospital Cancer Centre and the Dr. H. Bliss Murphy Cancer Centre who received CRT and had curative intent surgery (Sx) from 2005 to 2012. Patient, tumor and tx characteristics were correlated with treatment completion. Results: Of the 891 patients included, 886 patients had tx dose adjustments data available. 738 (83.2%) completed the planned neoadjuvant chemotherapy, while 148 (16.7%) failed to complete planned chemotherapy. Patients who required tx interruption/cessation or dose reduction were more likely to be female, elderly, had higher ECOG PS and were treated with fluorouracil (FU) chemotherapy in univariate analysis (see Table). On multivariable analysis, female gender (OR 1.807, 95% CI 1.02-3.2, p=0.042) and tx with FU (vs capecitabine) (OR 2.7, 95% CI 1.52-4.77, p=0.0007) were associated with dose reduction and tx interruption/cessation. Conclusions: Gender and type of chemotherapy are predictors of neoadjuvant chemotherapy interruption or dose reduction in rectal cancer. Careful monitoring of these patients is warranted during neoadjuvant CRT. [Table: see text]