QUANTIFYING REGIONAL HYPOXIA IN HUMAN TUMORS WITH POSITRON EMISSION TOMOGRAPHY OF [F-18] FLUOROMISONIDAZOLE - A PRETHERAPY STUDY OF 37 PATIENTS

Purpose: To assess pretreatment hypoxia in a variety of tumors using p ositron emission tomography (PET) after injection of the hypoxia-bindi ng radiopharmaceutical [F-18]fluoromisonidazole ([F-18]FMISO). Methods and Materials: Tumor fractional hypoxic volume (FHV) was determined i n 21 nonsmall cell lung cancer patients, 7 head and neck cancer patien ts, 4 prostate cancer patients, and 5 patients with other malignancies by quantitative PET imaging after injection of [F-18]FMISO (0.1 mCi/k g). The FHV was defined as the proportion of pixels in the imaged tumo r volume with a tissue:blood [F-18] activity ratio greater than or equ al to 1.4 at 120-160 min postinjection. A FHV > 0 was taken as evidenc e for tumor hypoxia. Results: Hypoxia was observed in 36 of 37 tumors studied with FMISO PET imaging; FHVs ranged from 0 to 94.7%. In nonsma ll cell lung cancers (n = 21), the median FHV was 47.6% and the range, 1.3 to 94.7%. There was no correlation between tumor size and FHV. In the seven head and neck carcinomas, the median PW was 8.8%, with a ra nge from 0.2 to 18.9%. In the group of four prostate cancers, the medi an and range were 18.2% and 0 to 93.9%, while in a group of five tumor s of different types the median FHV was 55.2% (range: 21.4 to 85.8%). Conclusions: Hypoxia was present in 97% of the tumors studied and the extent of hypoxia varied markedly between tumors in the same site or o f the same histology. Hypoxia also was distributed heterogeneously bet ween regions within a single tumor. These results are consistent with O-2 electrode measures with other types of human tumors. The intra- an d intertumor variability indicate the importance of making oxygenation measures in individual tumors and the necessity to sample as much of the tumor volume as possible. Copyright O 1996 Elsevier Science Inc.