Head and neck cancer

[CANCER RESEARCH 62, 7066 –7074, December 1, 2002]

Pimonidazole Binding and Tumor Vascularity Predict for Treatment Outcome in Head and Neck Cancer1
Johannes H. A. M. Kaanders,2 Karien I. E. M. Wijffels, Henri A. M. Marres, Anna S. E. Ljungkvist, Lucas A. M. Pop, Franciscus J. A. van den Hoogen, Peter C. M. de Wilde, Johan Bussink, James A. Raleigh, and Albert J. van der Kogel
Departments ofRadiation Oncology [J. H. A. M. K., K. I. E. M. W., A. S. E. L., L. A. M. P., J. B., A. J. v. d. K.], Otorhinolaryngology [K. I. E. M. W., H. A. M. M., F. J. A. v. d. H.], and Pathology and Maxillofacial Surgery [P. C. M. d. W.], University Medical Center Nijmegen, 6500 HB Nijmegen, The Netherlands, and Radiation Oncology and Toxicology, University of North Carolina, Chapel Hill, North Carolina27599-7512 [J. A. R.]

ABSTRACT
Hypoxia is associated with tumor aggressiveness and is an important cause of resistance to radiation treatment. Assays of tumor hypoxia could provide selection tools for hypoxia-modifying treatments. This study correlated the exogenous 2-nitroimidazole hypoxia marker 1-[(2-hydroxy-3piperidinyl)propyl]-2-nitroimidazole hydrochloride (pimonidazole) with theendogenous hypoxia-related marker carbonic anhydrase 9 (CA9) and with vascular parameters using immunohistochemical techniques and a computerized image analysis system. Tumor biopsies were obtained from patients with head and neck carcinomas that were potential candidates for a Phase II trial with accelerated radiotherapy combined with carbogen and nicotinamide (ARCON). If, after completion of thediagnostic workup, the eligibility criteria were met and informed consent was obtained, patients were treated with ARCON. Those patients that were not eligible or refused ARCON were treated with radiotherapy, surgery, or a combined modality. Forty-three biopsies were analyzed, and the results were related with treatment outcome. The distribution patterns of pimonidazole and CA9 were similar, although theCA9 signal was generally observed already at shorter distances from blood vessels. There was a weak but significant correlation between the relative tumor areas positive for pimonidazole binding and areas with CA9 expression. Locoregional tumor control was significantly lower for patients who had hypoxic tumors or tumors with low vascular density. The 2-year control rates were 48 versus 87% fortumors with high and low pimonidazole binding levels (stratified by median, P 0.01) and 48 and 88% for tumors with low and high vascular density (stratified by median, P 0.01). These associations disappeared in the subgroup of patients treated with ARCON. There was no relationship between the level of CA9 expression and treatment outcome. It is concluded that pimonidazole binding and vasculardensity can predict treatment outcome in head and neck cancer and may be useful as selection tools for hypoxia-modifying treatments. Pimonidazole and CA9 demonstrate concordant staining patterns, but the latter is a less specific marker for hypoxia.

INTRODUCTION In almost all solid tumors there is to some extent an imbalance between oxygen delivery and oxygen consumption resulting in hypoxia (1).Hypoxia is a powerful trigger for changes in gene expression and associated changes in the micromilieu. The altered genetic expression profile and the changed microenvironment stimulate clonal selection within the tumor cell population for cells with increased adaptation to hypoxia and drive the tumor toward a more malignant phenotype with increased resistance to anticancer treatments (2, 3).Received 5/3/02; accepted 9/30/02. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. 1 This study was supported by Dutch Cancer Society Grant KUN 98-1814 (to J. H. A. M. K., A. J. v. d. K.). 2 To whom requests for reprints...