A cancer survivor is a person with cancer of any type who is still living. Whether a person becomes a survivor at the time of diagnosis or after completing treatment, whether people who are actively dying are considered survivors, and whether healthy friends and family members of the cancer patient are also considered survivors, varies from group to group. Some people who have been diagnosed with cancer reject the term survivor or disagree with some definitions of it.

How many people are cancer survivors depends on the definition used. Nearly 65% of adults diagnosed with cancer in the developed world are expected to live at least five years after the cancer is discovered. In the U.S. for example, about 11 million Americans alive today—one in 30 people–are either currently undergoing treatment for cancer or have done so in the past.

Many cancer survivors describe the process of living with and beating cancer as a life-changing experience. It is not uncommon for survivors to use the experience as opportunities for creative self-transformation into a "better person" or as motivation to meet goals of great personal importance, such as climbing a mountain or reconciling with an estranged family member. This process of posttraumatic growth is called benefit finding. Cancer survivors often have specific medical and non-medical needs related to their cancer experience.