Occurrence of irreversible sinusoidal obstruction syndrome during adjuvant chemotherapy for colorectal cancer using oxaliplatin: A multi-center study

546 Background: Oxaliplatin reduces the recurrence rate after curative surgery for stage III colorectal cancer. However, it can cause hepatic sinusoidal obstruction syndrome (SOS), an adverse effect that creates morbidity after liver resection for recurrence. SOS has conventionally been diagnosed by liver biopsy, which is invasive. We have reported that a 10% increase in splenic volume (SV) indicates SOS (J Surg Oncol 2017). In this multi-center study, we measured SV to evaluate SOS caused by adjuvant chemotherapy. Methods: This multi-center study included the participants of the FACOS study, which included patients with Stage III colon cancer. Participants received 12 cycles of mFOLFOX6 or eight cycles of XELOX as adjuvant chemotherapy. We used multi-detector raw CT to measure SV three times; before surgery, on completion of adjuvant chemotherapy, and 1-year after completing adjuvant chemotherapy. CT images were taken in 5-mm slices. SV was calculated by using a volume calculator SYNAPSE VINCENT v3.0(Fujifilm, Japan). Results: The FACOS study included 130 patients, 16.9% of whom discontinued treatment. The mean relative dose intensity (RDI) of oxaliplatin was 80.3%. Grade 3 neutropenia, thrombocytopenia, and neuropathy were observed in 28.5%, 6.2%, and 4.6% of patients, respectively. The 3 year DFS was 82.2%. We analyzed data of 75 patients (57.7%) for whom the three CT studies were available. SV on completing chemotherapy (median 181 cm3) and SV 1-year after completing chemotherapy (141 cm3) were significantly higher than that before surgery (128 cm3) (P < 0.001). SV increased by more than 10% after chemotherapy in 72% and was still increased 1 year after chemotherapy in 51% of patients. Conclusions: In our previous single center study, SV had increased in 84% on completing chemotherapy and was still increased in 47% 1 year after completing chemotherapy. Adjuvant chemotherapy without oxaliplatin induced SV increases in only 20% of patients on completing chemotherapy. Thus, these results are reproducible and show the potential of oxaliplatin to induce SOS. Oxaliplatin frequently induces SOS and this SOS persists for over 1 year in half of affected patients. Clinical trial information: UMIN000005427.