INTRATUMORAL OXYGEN-TENSION IN METASTATIC MELANOMA

Tumour hypoxia can lead to a decrease in the biological effectiveness of radiation and alkylating agents. Few data are available on oxygen t ension (PO2) in melanoma. In 20 patients with past history of melanoma , PO2 was evaluated in normal tissues and suspected metastatic lesions (nodes and skin metastases). Oxygen tension was measured using a need le probe technique (KIMOC-6650 histograph, Eppendorf, Germany), the da y before the surgical removal of the suspected metastatic lesion. Hist ological confirmation of the malignant origin of the removed lesion wa s obtained in 18 cases. In two cases invasion by the known melanoma wa s not seen histologically. The median PO2 for normal tissues was 40.5 mmHg. For tumours, the median PO2 was 11.6 mmHg, and it was 17.1 mmHg in nodes and 6.7 mmHg in skin metastases. Very low values (< 2 mmHg) a ccounted for 20% of the recorded values in nodes and 15% in skin metas tases. when analysed according to the node size (< or greater than or equal to 3 cm in diameter), the median PO2 was 10.4 mmHg in large node s (six patients) and 53.3 mmHg in small nodes (six patients). For the two non-tumoral lesions, the median PO2 values were 20.9 and 25.1 mmHg , with no values below 10 mmHg. Thus a decrease in PO2 values, probabl y corresponding to tumour hypoxia, was found in most of the metastatic tumours when compared with normal tissues. The prognostic value of th ese PO2 measurements in melanoma remains to be demonstrated in the tum our response to radiotherapy or alkylating agents. However, tumour hyp oxia can already be investigated as a target for new treatment modalit ies in metastatic melanoma.