Purpose: In a continuous effort to seek for anticancer treatments with minimal side effects, we aim at proving the feasibility of the Intraoperative Avidination for Radionuclide Therapy, a new procedure for partial breast irradiation.
Experimental design: To assess doses of 90Y-DOTA-biotin to target (i.e., breast tumor bed) and nontarget organs, we did simulation studies with 111In-DOTA-biotin in 10 candidates for conservative breast surgery. Immediately after quadrantectomy, patients were injected with 100-mg avidin in the tumor bed. On the following day, patients were given 111In-DOTA-biotin (approximately 111 MBq) i.v. after appropriate chase of biotinylated albumin (20 mg) to remove circulating avidin. Biokinetic studies were done by measuring radioactivity in scheduled blood samples, 48-h urine collection, and through scintigraphic images. The medical internal radiation dose formalism (OLINDA code) enabled dosimetry assessment in target and nontarget organs.
Results: Images showed early and long-lasting radioactive biotin uptake in the operated breast. Rapid blood clearance (<1% at 12 h) and urine excretion (>75% at 24 h) were observed. Absorbed doses, expressed as mean+/-SD in Gy/GBq, were as low as 0.15+/-0.05 in lungs, 0.10+/-0.02 in heart, 0.06+/-0.02 in red marrow, 1.30+/-0.50 in kidneys, 1.50+/-0.30 in urinary bladder, and 0.06+/-0.02 in total body, whereas in the targeted area, they increased to 5.5+/-1.1 Gy/GBq (50% ISOROI) and 4.8+/-1.0 Gy/GBq (30% ISOROI).
Conclusion: Our preliminary results suggest that Intraoperative Avidination for Radionuclide Therapy is a simple and feasible procedure that may improve breast cancer patients' postsurgical management by shortening radiotherapy duration.