The role of religion and spirituality in health has received increasing attention in the scientific and lay literature. While the scientific attention to this issue has expanded, there continue to be methodological and measurement concerns that often prevent firm conclusions about health and adjustment benefits. Limited attention has been provided to the role of spirituality and religion in cancer. This is true when both disease outcome and adjustment are considered. A recent 'levels of evidence' review examining the link between physical health and religion or spirituality found little overall support for the hypotheses that religion or spirituality impact cancer progression or mortality. Studies examining their impact on quality of life and adjustment are decidedly mixed. In sum, research specifically focusing on the role of religion or spirituality on cancer outcomes has been surprisingly sparse. Such research presents a number of methodological and measurement challenges. Due to these unmet challenges in the literature to date, it is premature to determine what role religion and spirituality play in disease, adjustment, or quality of life outcomes in cancer. A number of suggestions are made for continued research in this area.