Background: A powerful and improved technique, Proton Induced X-ray Emission (PIXE) has been performed-yielding the elemental composition of 17 samples of surgically excised malignant and normal tumors of breast tissue. The samples without any further process as thick targets were put on capton foil backing. There are no homogenizing processes. The PIXE spectra analysis was performed using he non-linear least square fitting code AXIL and GUPIX.

Materials and Methods: The samples are taken from patients in the wide range of age and are bombarded by 2.0 Me v energy proton beams produced by van de graff accelerator in vacuum. The quantitative comparison between two types of tissues was evaluated by assessing the presence of c alcium, Potassium, Iron, Copper and Zinc, as minor and trace elements.

Results: Results in this study indicate that relative values of Cu / Zn, P / K and also Ca and S in benign type were higher than those in malignant type, but the concentration of Fe and Zn in cancerous tissues was significantly higher than those for benign type.

Conclusion: Results suggest significant elevation of Zinc in the pathological tissues. Cu/Zn ratio for both type of tissues are evaluated. The results show that this ratio in patients with breast cancer is significantly lower than the normal group. Selenium and Arsenic was not obtained in any of 17 samples. Most of the tissues of benign kind (Fibrocystic and Fibro adenoma) contain Cadmium. Calcium concentration in normal tissues is significantly higher than tumorous tissues. Iran . J. Radiat. Res., 2003; 1(1): 23 - 27.