Variable implementation of optimal therapeutic strategies in metastatic colorectal cancer: Reviewing rates of liver resection and triplet chemotherapy across Australian hospitals as potential quality indicators.

248 Background: Quality indicators (QI) are essential to monitor the efficacy of cancer care and to guide quality improvement, however many are derived from ‘expert consensus’ and are not validated against outcomes. Moreover, the majority of oncological QI are defined in the surgical setting, with only a paucity of QI for the treatment of metastatic disease. We aimed to define and validate novel QI for metastatic colorectal cancer (mCRC) based on therapeutic approaches associated with a proven survival benefit. Methods: Data was analysed from TRACC, a multisite Australian registry collecting prospective demographic, tumour, treatment and outcome data for mCRC. We identified all patients diagnosed across 11 hospitals and explored variation by site with regards to patient and tumour characteristics, first-line chemotherapy administration and resection of oligometastatic disease. Log-rank testing and Kaplan-Meier curves compare overall survival (OS) between sites, and Pearson correlation was used to assess associations with each QI. Results: We examined data from 3132 patients diagnosed with mCRC between July 2009 – April 2021. Median age was 66 years (range 62 – 71 years by site), ECOG 0-1 81% (range 69 – 96% by site), and Charlson Comorbidity Index ≤2 43% (33 – 59% by site). Multivariate analysis confirmed association of known adverse prognostic factors with inferior OS (poor ECOG, right sided primary, KRAS or BRAF mutation, all p <0.05). Median OS for entire cohort was 26.2 months (95%CI 24.9 – 27.3 months), and varied by hospital site from 20.1 – 36.1 months (p<0.001). Of the QI evaluated, rate of triplet chemotherapy (FOLFOXIRI) administration (2.8 – 13.2% by site) was very strongly correlated with OS (R2 = 0.851), rate of liver resection (9.8 – 23.2% by site) was moderately correlated (R2 = 0.523), and rates of active treatment with first-line chemotherapy (63 - 90% by site) were weakly correlated (R2 = 0.209). Other proposed QI such as rates of lung metastases resection or chemotherapy administration in the elderly showed significant variation by site, but did not correlate with survival. Conclusions: There is significant variation in OS for patients with mCRC in these Australian hospitals, with major differences in treatment approaches. Treatment strategies known to improve survival outcomes, such as triplet FOLFOXIRI chemotherapy and resection of liver metastases, may be potential QI to benchmark and track quality improvement over time. Further analysis will determine the impact of baseline patient populations between sites, and to correlate these QI with other quality measures.