First‐pass uptake of methotrexate after intra‐arterial bolus injection in human head and neck cancers

The aim of this study was to quantify first-pass uptake of methotrexate into tumour and healthy tissue after intra-arterial (i.a.) injection in patients with head and neck cancers. Twenty-one patients were studied ; during surgery, a bolus injection of 10 mg of 3 H-labelled methotrexate was administered into the tumour-supplying artery. At 15-20 s after injection, and again 2-3 h later, a biopsy of the tumour and of surrounding healthy tissue was taken and radioactivity was measured. In 8 of 17 pretreated patients the biopsy specimens contained no tumour cells. In tumour-bearing patients, radioactivity in tumour was three times higher than in healthy tissue (P = 0.006). In tumour-negative patients there was no difference in activity between the two biopsy sites (P = 0.889). However, after 2-3 h the concentration of methotrexate in all surgical specimens returned to near background level and the initial difference between tumour-positive and tumour-negative samples was lost. Our results show that i.a. injection of methotrexate does not necessarily lead to high tumour cell exposure.