S048 Low skeletal muscle radiodensity is a risk factor for adjuvant chemotherapy discontinuation in colorectal cancer

Abstract Background Previously, we reported SMR (skeletal muscle radiodensity) as a potential prognostic marker for colorectal cancer. However, there have been limited studies on the association between SMR and the continuation of adjuvant chemotherapy in colorectal cancer. Methods In this retrospective study, 143 colorectal cancer patients underwent curative surgery and adjuvant chemotherapy using the CAPOX regimen. Patients' SMRs were measured from preoperative CT images and divided into low (bottom quarter) and high (top three quarters) SMR groups. We compared chemotherapy cycles, capecitabine and oxaliplatin doses, and adverse effects in each group. Results The low SMR group had significantly fewer patients completing adjuvant chemotherapy compared to the high SMR group (44% vs. 68%, P<0.01). Capecitabine and oxaliplatin doses were also lower in the low SMR group. Incidences of Grade 2 or Grade 3 adverse effects did not differ between groups, but treatment discontinuation due to adverse effects was significantly higher in the low SMR group. Logistic regression analysis revealed Stage III disease (odds ratio 9.30, 95% CI: 1.07-80.54) and low SMR (odds ratio 3.09, 95% CI: 1.07-8.94) as factors associated with unsuccessful treatment completion. Additionally, a higher proportion of low SMR patients received fewer than 2 cycles of chemotherapy (50% vs. 12%). Conclusion The low SMR group showed higher treatment incompletion rates and received lower drug doses during adjuvant chemotherapy. Low SMR independently contributed to treatment non-completion in colorectal cancer patients.