Radiopeptide transmitted internal irradiation of non-iodophil thyroid cancer and conventionally untreatable medullary thyroid cancer using [Y-90]-DOTA-D-Phe(1)-Tyr(3)-octreotide: a pilot study

Aim Differentiated thyroid carcinomas (DTC) and medullary thyroid carcinoma s (MTC) overexpress somatostatin receptor subtypes (sstr). The aim of this pilot study was to evaluate the tumour response of thyroid carcinomas to ta rgeted irradiation with the radiolabelled somatostatin analogue [Y-90]-1,4, 7,10-tetra-azacyclododecan-4,7,10-tricarboxy -methyl-1-yl-acetyl-D-Phe(1)-T yr(3)-octreotide ([Y-90]-DOTA-D-Phe(1)-Tyr(3)-octreotide, or Y-90-DOTATOC) which has a high affinity to subtype 2 and a low affinity to subtype 5. It shows no affinity to sstr1, sstr3 and sstr4. Patients and methods Twenty patients (mean age 58 years; 50% female, 50% ma le) with thyroid cancer were included (medullary thyroid cancer (MTC), 12 p atients; differentiated thyroid cancer (DTC), seven patients; papillar carc inoma (PC), four patients; follicular carcinoma (FC), three patients; anapl astic carcinoma (AC), one patient). All patients had been therapy resistant and had progressive disease before Y-90-DOTATOC therapy. The dose applied was between totals of 1700 MBq.m(-2) to 7400 MBq.m(-2) Y-90- DOTATOC, admin istered in one to four injections at intervals of 6 weeks. In the case of t umour progression under therapy, treatment was terminated. Results The overall antitumour effect (objective response and stable diseas e) was 35%: in MTC 42%, in DTC 29%, and in AC 0%. The objective overall res ponse rate was 0%. A stable disease was achieved in 35% (7/20), and progres sive disease was found in 65% (13/20). The median time to progression was 8 months, with a median follow-up of 15 months. The treatment was very well tolerated. There were no grade III/IV haematological or renal toxicities. Conclusion Targeted radiotherapy using Y-90-DOTATOC is able to stop tumour progression in a small number of patients and therefore may be an alternati ve treatment option for resistant disease. More significant tumour response s in thyroid and medullary thyroid cancer may be obtained by using radiopep tides with pan-somatostatin characteristics. ((C) 2001 Lippincott Williams & Wilkins).