Tc-99(m) labelled HL91 versus computed tomography and biopsy for the visualization of tumour recurrence of squamous head and neck carcinoma

This phase I pilot study reports on (1) the safety and feasibility of Tc-99 (m)-HL91, an amine oxime core radioligand that has shown oxygen dependent b inding, and imaging; and (2) its usefulness for the visualization of local tumour recurrence of a biopsy proven squamous cell carcinoma of the head an d neck (SCCHN) as compared to spiral computed tomogaphy (CT) and biopsy. Ni ne men (mean age 33 years, range 34-74 years) were prospectively included. For safety measurements, vital signs were recorded and serum chemical analy sis carried out, with a complete blood cell count and urine analysis, and a n ECG was performed prior to injection of Tc-99(m)-HL91 and repeated during the investigation. Single photon emission computed tomography (SPECT) scan s of the head and neck, and of a standard, were performed at 2 h and 4 h po st-injection of 740 MBq Tc-99(m)-HL91. Tumour-to-normal tissue background ( T/N) ratios and percentage uptake were measured for ail Tc-99(m)-HL91 scans . Spiral CT scans were obtained using a Somaton 4+ Siemens scanner within 1 week from the Tc-99(m)-HL91 scans. Based on CT and the Tc-99(m)-HL91 scan findings guided biopsies were performed. No adverse or subjective side effe cts were noticed. Vital signs, ECG findings, clinical laboratory, blood and urine assays remained stable in all patients. Spiral CT suggested local re currence in 5/9 patients accompanied by nodal involvement in three, all of which proved positive on biopsy. Tc-99(m)-HL91 scintigraphy was false posit ive in one patient and true positive (TP) in 3/5 local recurrences and two out of three sites of lymph node involvement depicted by spiral CT. The mea n T/N ratios at 2 h and 4 h in TPs were 1.28 (range 1.1-1.66) and 1.40 (ran ge 1.0-1.6), respectively. The corresponding absolute percentages of Tc-99( m)-HL91 lesional uptake at 2 h and 4 h were mu =0.05% (SD = 0.03%) and mu = 0.048% (SD = 0.035%). The findings suggest Tc-99(m)-HL91 is a safe radioli gand and that metabolic binding in a large fraction but not all of local SC CHN recurrences may be expected. The inference that tumour Tc-99(m)-HL91 av idity could be a non-invasive measure of tumour hypoxia deserves however in dependent confirmation with needle oximetry. (C) 2001 Lippincott Williams & Wilkins).