Trace element profiles in cancer patients

It has become evident over the last two decades that there is an intimate relationship between the trace elements and cancer. Some trace elements have been shown to be carcinogens, others appear to provide protection against cancer. Profound changes in trace element concentrations and distribution occur in patients with cancer, but most changes remain undefined. A review of a number of studies of trace element changes in patients with cancer demonstrates that simple correlations of trace element levels in disease are of only limited use. Such reports underscore the need for large-scale studies that consider the many variables of malignancies and of trace element chemistry. The variables that must be considered for cancer include tissue of origin; histologic, pathologic and clinical staging; nutritional status as reflected by serum levels of calcium, iron, magnesium, phosphorus, the electrolytes, pH, albumen, and globulin; endocrine balance, effects of previous and concurrent therapies such as surgery, chemotherapy, hormonal manipulation, immunotherapy, and radiotherapy; history of exposure to toxic agents; and the presence of other disease. Similarly, trace element studies entail variables that must be considered and controlled prospectively, including timing and techniques of sampling, storage, and analysis, and simultaneous measurement of at least the majority of possibly interrelated elements rather than studying one element at a time. The various national cooperative oncology groups such as ECOG, SWOG, and SEOG now offer unusually well-studied groups of cancer patients who are managed according to carefully and prospectively defined protocols in participating institutions. With present knowledge, it is now time to approach these groups with a proposal to incorporate trace element studies in their protocols. A potential protocol will be discussed.