A significant change of vitamin E and malondialdehyde plasma concentrations was reported in breast cancer patients. This change was unexpected because vitamin E was higher and malondialdehyde lower in cases than in controls, and the difference was more significant in young rather than older women. The first aim of this study was to determine whether these changes were associated only with breast cancer, or with hormone-related cancers, and/or cancers associated with nutritional risk factors or with all types of cancers. Measurements were performed before therapy on 269 hospital-based controls and on 146 patients with various carcinomas. Vitamin E:total cholesterol increased and malondialdehyde plasma concentration decreased with tumor size and progression, without relation to the site. The second aim was to understand the difference in the change observed between young and old breast cancer patients. These analytes were measured in 365 breast cancer patients according to three prognosis factors: pathology, tumor size and estrogen receptors. Vitamin E:total cholesterol significantly decreased with estrogen receptor amount. Malondialdehyde plasma concentration decreased with severity of pathology and tumor size. Together, these data support the association of an altered oxidant-antioxidant profile in cancer patients with tumor growth and progression.