Combined radioimmunotherapy and radiotherapy of liver metastases from colorectal cancer: A feasibility study

Background A combination of radioimmunotherapy (RIT) and radiotherapy (RT) should allow one to increase the dose of radiation targeting a particular t umour without the concomitant increase of toxic side effects. This might be obtained if the dose limiting side effect of each individual radiation the rapy concerned different organs. Methods. Six patients with limited liver m etastatic disease from colorectal cancer were treated with 6.9 GBq (range 4 .7 to 8.4 GBq) I-131- labelled anti-CEA MAb F(ab')(2) fragments combined wi th 20 Gy RT to the liver. Both treatments were given in close association a ccording to timing schedules evaluated in animals that gave the best result s. Results. Reversible bone marrow and liver toxicity was observed in 6 and 5 patients, respectively. Three patients who first received 20 Cy RT to th e liver, showed a significant platelet drop upon completion of RT. Repeat c omputerized tomography (CT) after 2 months showed a minor response in I pat ient and stable disease in 3 patients. Conclusion. The study shows potentia l ways of combining RIT and RT, suggesting that this combination is feasibl e for the treatment of liver metastases.