Evidence both supports and rejects the view that psychological factors and/or stress (PF&S) are related to increased risk of cancer incidence, relapse and mortality in man. Issues relating to genetics and to stress are addressed. Reasons are given why one should be cautious in generalizing to the human case from animal data on stress. Evidence at hand, including demographic, suggests that if PF&S do have an effect on incidence of cancer in the human, it is small. The relationship of PF&S to cancer prognosis is felt to be more likely. Some theoretical speculations about recent relapse and survival findings are given, with associated hypotheses.