I'mop ,7 (,omea Vol. 16, pp. 261 265 0014-29ii4/~0/0201-0261 S02,00~0 l~clgamon Press. 1980 Printed ill Great Britain Radioiodinated Fibrinogen in the Evaluation of Patients with Osteosarcoma D. CASARA,* G. CARTEL,~" S. COSTA,J- V. PENGO, {M. FIORENTINO~ and F. CALZAVARA* *Divisione di Radioterapia e Medicina Nucleare, Ospedale Civile di Padova, Padova, Italy -~ Divisione di Oncologia Medica, Ospedale Civile di Padova, Padova, Italy {Clinica Medica I °, Universitd di Padova, Padova, Italy Abstract--Usefulness of radioiodinated fibrinogen in tumour localization and control of coagulation process in patientswith osteosarcoma was evaluated. Turnoutexternal detection demonstrated positive localization in all cases ofosteosarcoma before any treatment and in 2 cases of relapse of the disease 4--6 months after the radiation therapy. Patients with osteosarcoma showed fibrinogen half-life, survival and turnover significantly faster than control subjects. FDP levels were correlated to half-life lowering. Heparin therapy corrected into normal range fibrinogen half-life in 3 patients treated. Theseresults suggest that the alteration of fibrinogen metabolism depends on the presence of osteosarcoma and on the concentration of this agent in cancer tissues and propose radioiodinated fibrinogen as a diagnostic agent in clinical staging and follow- up of the patients suffering frorn osteosarcoma. I N T R O D U C T I O N IN THE last decade survival of the patients with osteosarcoma has improved as a result of new therapeutic regimens |1, 2] and as a result of increased accuracy in clinical staging of disease.Nuclear medicine diagnostic tech- niques can play an important role in the clinical staging and follow-up of patients, suf- fering from osteosarcoma. In patients with lower limb osteosarcomas, bone scanning can present false positive uptake in distal areas below the primitive tumour, and tumour seek- ing agents, such as 67Ga citrate or radjo- bleomycin are more specific and manageable for defining the extent of disease [3]. Abnormal coagulation parameters are fre- quently present in patients with neoplastic disease [4, 5], moreover, alteration in fibri- nogen kinetics have been demonstrated in cancer patients even when plasma fibrinogen levels were normal [6, 7]. Radiofibrinogen has been shown to localize in cancer tissues [8] and was proposed in tumour scintigraphic detection [9]. We used radioiodinated fibrinogen in the study of patients with osteosarcoma, in the .\CCClm'd 1 [.]unc 197.q. monitoring of the coagulation process and t u l ' n ( ) u r l l n i / ~ l l l ~ , MATERIALS AND M E T H O D S Studies were performed in 7 patients with osteosarcoma during clinical staging before any treatment and in 10 healthy subjects. For fibrinogen kinetics the radioactivity in- jected i.v. was 50-100#Ci of 125I in 1 mg of iodinated fibrinogen (Sorin Radiochemical Center). Blood samples were withdrawn in EDTA 10 min after injection and twice daily for 6-7 days. Only the second exponential of the disappearance curve was considered for t/2 calculation. Fibrinogen survival was de- termined from the half-life divided by the natural logarithm of 2. Fibrinogen turnover was calculated from the fibrinogen concen- tration divided by, thesurvival time. Platelet counts, fibrinogen concentration, FDP con- centration, Quick" and Howell time were cal- culated with standard techniques and con- sidered in a coagulative parameter table. Student's t-test was used to determine signi- ficant difference from control. For tumour detection, 200-300/~Ci of 131I fibrinogen and 1.SmCi of STCo bleornycin were used. For both agents scintigraphic re- F 261