Cancer patients face immune system challenges primarily in 2 areas:(1) fighting malignancies through immune mechanisms and (2) confronting the immune-suppressive effects of the disease and treatments. In this Point-Counterpoint, we explore the potential role of the immune system with practitioners and researchers active in the area of integrative and alternative cancer treatment:D. Barry Boyd, MD, a medical oncologist who uses integrative approaches in his practice; Nicholas Gonzalez, MD, a physician in private practice who uses an alternative medicine intervention for cancer patients based on the work of Dr. William Kelley; and Aristo Vojdani, PhD, of Immunosciences Lab Inc., a diagnostic and research facility that specializes in innovative microbiology and immunology laboratory testing. Drs. Gonzalez and Vojdani were interviewed by telephone for this article, whereas Dr. Boyd submitted written responses to our questions. Mobilizing the body’s immune system against cancer has long been an elusive goal in cancer medicine. The idea that the human immune system provides continuous surveillance for cancer cells is appealing to the general public and continues to be presented as gospel in many popular health books, particularly those aligned with alternative medicine. It seems almost axiomatic to the layperson that a system designed to help the body ward off pathogenic influences should also help ferret out cancer cells. When immune surveillance falters, cancers can more readily develop and progress. The allure of this belief is further heightened by the recognition that many factors within our control can influence immune function, and by the fervent hope that enhancing such immune function should, in turn, support one’s ability to combat cancer. Originally proposed by Ehrlich in 1909 and elaborated on by Burnet in the 1960s, the immune surveillance hypothesis states that cell-mediated immunity can recognize and destroy proliferating cancer cells.