Free radicals and breast cancer.

For the most part, the article in the Forum section titled "Free Radicals and Breast Cancer" [EHP 104:82 1 (1996)] accurately describes our paper "Progression of Human Breast Cancers to the Metastatic State Is Linked to Hydroxyl Radical-induced DNA Damage" (1). However, it was claimed that Some scientists have questioned the methodologies used by Malins and note that studies published in the February 1996 issue of Carcinogenesis and the December 1995 issue of Chemical Research in Toxicology failed to duplicate Malins' initial results using identical methods. The authors of the articles, Douki et al. (2) and Ravanat et al. (3), were concerned primarily with the possibility of DNA base oxidations in the formation of trimethysilyl derivatives for gas chromatography-mass spectrometry (GC-MS). The focus was not on our work and the authors did not attempt to duplicate our results or dispute our conclusions. In our studies of base changes in relation to breast cancer, we consistently compared control and test samples under identical conditions that favored the exclusion of oxygen. Ravanat et al. (3) found no fault with this approach, stating that the differences in the levels of 8-oxoGua observed between controls and treated samples should not be due to the artifactual oxidation of guanine during the derivatiza-tion, assuming that the samples were treated in an identical fashion. This conclusion would logically include other bases, although guanine may be particularly susceptible to oxidation. The Forum article does not mention the findings of Musarrat et al. (4) or Nagashima et al. (5), which are consistent with our conclusions linking base damage to breast cancer (6). Overall, we applaud the effort to explore the possibility that individual bases are artifactually oxidized using the GC-MS procedures, particularly because of mounting evidence relating the base lesions to carcinogenesis. For our part, we have recently employed 13C/15N-labeled bases as standards to correct for possible oxidation in determining individual base lesions. Prognostic and aetiological relevance of 8-hydroxyguanosine in human breast carcinogen-esis. 8-Hydroxydeoxygranosine levels in DNA of human breast cancers are not significantly different from those of non-cancerous breast tissues by the HPLC-ECD method. Critical Technologies Institute Additional fellowships at EPA are for 10 weeks in the summer. Applicants must be US citizens and must have a PhD or equivalent doctoral level degree at the time of application from any physical, biological, or social science or any field of engineering. Applicants with a master's degree in engineering and …