Internal Radiation May Improve Outcomes in Right-sided Colorectal Tumors

Combined treatment with first-line chemotherapy and selective internal radiation therapy (SIRT) led to a better survival rate in patients whose liver metastases had originated from right-sided primary colorectal tumors, compared with patients who were treated with chemotherapy alone. The survival rate was 36% better in those who received the combination treatment, researchers reported in an abstract presented at the ESMO 19th World Congress on Gastrointestinal Cancer.

Patients with colorectal cancer that metastasizes to the liver typically have a worse prognosis if their primary tumor is located on the right side of the colon, but the new findings offer better options for those with right-sided primary tumors, the investigators said.

The study analyzed data from 739 patients from the SIRFLOX and FOXFIRE-Global completed studies. Patients with previously untreated liver-only or liver-dominant metastatic colorectal cancer (mCRC) were randomized to receive either standard chemotherapy alone or standard chemotherapy combined with a single administration of SIRT. The chemotherapy was the mFOLFOX6 regimen, with most patients also receiving bevacizumab, and the SIRT used Y-90 resin microspheres.

Location of primary tumors was recorded prospectively in case report form. Twenty-four percent of patients had a primary right-sided tumor, while 73% had a left-sided tumor, and 3% had tumors on both sides of the colon or an unknown primary tumor site. Study results showed no difference in overall outcomes between the chemotherapy and combined treatment groups. Median overall survival was about 24 months, and progression-free survival was approximately 11 months.

Separate examination of right-sided patients and left-sided patients showed clear differences in survival though. When SIRT was added to the chemotherapy of right-sided patients, overall survival was significantly better (22 months) than the overall survival of right-sided patients who had chemotherapy alone (17.1 months) (p=0.007; hazard ratio [HR]: 0.64; 95% CI: 0.46-0.89). However, the same effect was not observed in overall survival of left-sided patients, who had an overall survival of 24.6 months with combined treatment and 25.6 months with chemotherapy alone (p=0.279, HR=1.12; 95% CI: 0.92-1.36).

“These findings are being validated in the remaining FOXFIRE trial cohort. These data add to the growing literature describing primary tumour location-based differences in mCRC outcomes with some treatments, and may support a side-based approach to treatment selection including SIRT,” the researchers wrote. They added that “the biological drivers of these differences remain to be defined.”

Reference

van Hazel G, Volker H, Navesh S, et al. Impact of primary tumour location on survival in patients with metastatic colorectal cancer receiving selective internal radiation therapy and chemotherapy as first-line therapy. Abstract LBA-006. Presented July 1, 2017.