Carbon-ion Radiotherapy for Oligometastatic Colorectal Cancer in the Liver or Lung.

Background/aim: We aimed to evaluate the clinical outcomes of oligometastatic colorectal cancer in the liver and lung treated with carbon-ion radiotherapy (C-ion RT).
Patients and Methods: Nineteen consecutive patients with oligometastatic colorectal cancer in the liver or lung who received C-ion RT were analyzed. The doses of C-ion RT were 60.0 Gy [relative biological effectiveness (RBE)] in 4 fractions, 60.0 Gy (RBE) in 12 fractions, or 64.8 Gy (BRE) in 12 fractions.
Results: The median follow-up duration was 19 months. There were 23 tumors in 19 patients. The 2-year overall survival and local control rates for the whole patient cohort were 100% and 67%, respectively. None of the patients developed grade 2 or higher acute or late toxicities.
Conclusion: C-ion RT for oligometastatic colorectal cancer in liver and lung provides favorable clinical outcomes. These outcomes suggest C-ion RT is a treatment option for oligometastatic colorectal cancer in liver and lung.