Interactions between molecules control intra- and intercellular physiology. Cancer is emerging as a disease in which individual molecules are either overproduced, mutated, expressed at inappropriate stages of development, or lost due to inheritance or aberrant mitotic divisions. The major players in this contest of cellular control are growth factors, growth factor receptors (GFRs), signal transducers, and dominant or suppressor/recessive oncogenes. The tumors most frequently removed by surgeons have been reported to have changes in one or another of these types of molecules. The concept of multistage carcinogenesis, whereby malignancy arises after a sequence of changes that are cumulative, and passed from progenitor to daughter cells, is also being defined as a sequence of molecular, genetic, and chromosomal alterations. Molecular antineoplastic therapy is in early stages of development at the laboratory bench. The future may see patients screened for cancer susceptibility, evaluated for adjuvant therapy, and chosen for particular treatment based on molecular analysis. The types of cancer operations and the scope of surgical resection may change as molecular techniques enhance oncological treatment.