Abstract 3320
Background
Sidedness of primary is an established prognostic factor in mCRC and recently has been shown to be an important predictive factor for patients (pts) treated with EGFR-Ab (always in combination with chemotherapy) in 1st and 2nd line settings. Limited data is available in 3rd line and beyond, where EGFR-Ab are used either as monotherapy or with chemotherapy. In Ontario, Canada, public funding of EGFR-Ab is restricted to chemorefractory disease. This study examines the impact of sidedness on overall survival (OS) in chemorefractory mCRC treated with EGFR-Ab monotherapy and combination.
Methods
This population-based retrospective cohort study used linked data from the Institute for Clinical Evaluative Sciences to evaluate mCRC pts treated in Ontario with EGFR-Ab from Jan 2006-Dec 2014. Over 99% of cases are captured via the Ontario Cancer Registry. The primary outcome was OS. Monotherapy v combination was compared by panitumumab (pani; funded only as monotherapy) v cetuximab (cet; funded only with chemotherapy) outcomes. Sidedness was determined by ICD-10 code as right (R; including transverse colon) or left (L).
Results
Of 67117 CRC pts,1553 received EGFR-Ab for refractory mCRC (429 R, 1080 L, 44 unknown). 71% received pani. R were more commonly female, with significantly shorter time (months, m) from diagnosis to EGFR-Ab therapy (mean ± SD: 28.7 ± 18.3 v 32.8 ± 19.2; p
Conclusions
This large population cohort demonstrates that R sidedness is significantly predictive for survival with EGFR-Ab in refractory mCRC, consistent with findings in earlier lines of therapy. The differences are particularly seen with monotherapy. L sided cancers appear to benefit equally from monotherapy as combination.
Clinical trial identification
Legal entity responsible for the study
Monash University
Funding
None
Disclosure
All authors have declared no conflicts of interest.