Vitamin C has been suggested and disputed as an anti-cancer agent. For cells in culture, no preferential effect against any type of cancer has yet been demonstrated. Our aim here is to show that vitamin C is selectively toxic to at least one type of malignant cell--a melanoma--at concentrations that might be attained in humans. Copper ions react with ascorbate and generate free radicals in solution. Ascorbate when combined with copper rapidly reduces the viscosity of DNA solutions and has exhibited some carcinostatic effects on transplanted sarcoma 180 tumours in mice. We reasoned that the elevated copper concentration in melanoma could result in a more selective toxicity for ascorbate.

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Background. Tumor hypoxia could play a role in the response to radiation therapy. Few data are available on oxygen tension (pO2) measurements in head and neck tumors. Methods. The KIMOC‐6650 Histograph (Eppendorf, Hamburg, Germany) was used to measure the oxygenation status of normal tissues and head and neck tumors in 20 patients. Results. The median pO2 for normal tissues was 43 mmHg with very low pO2 values (2.0 mmHg or less) recorded in two patients. Low median pO2 levels (10 mmHg or less) were recorded in 2 of 5 primary tumors and in 11 of 15 metastatic lymphadenopathies, with very low values in 11 nodes. The median pO2 in tumors was lower than that of normal tissues in 12 of 15 patients with comparative measurements. Oxygen tension was recorded in three nodes after an evaluation of tissue density (by computed tomographic scanner); in two nodes, the mean and median pO2 values were lower in the hypodense areas than in isodense areas. The data for N2 and N3 nodes showed significantly more values below 2.0 mmHg as nodal size increased (P ≤ 104, by chi‐square test). No systematic decrease in pO2 was recorded from the periphery to the center of the tumors. Conclusions. Very low pO2 values, corresponding to radiobiologic hypoxia, were found in most of these tumors. The prognostic value of these pO2 measurements in regard to treatment response remains to be demonstrated.

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