Background: Many psycho-oncology studies use posttraumatic growth (PTG) measures designed for general trauma experiences, and as such they may not take into account life changes associated with a health-related context. Method: Study 1, a thematic analysis of written narratives (N = 209), emphasised cancer survivors’ newfound compassion. Study 2, with 504 prostate cancer survivors, measured the Posttraumatic Growth Inventory including five additional items derived from Study 1 to represent increased compassion. Findings: A Principal Components Analysis revealed a six-component structure after deleting eight items. Components related to compassion, new possibilities, relating to others, personal strength, appreciation of life, and spiritual change. Compassion accounted for 48.9% of variance, with the overall model accounting for 79.9% of variance. Strong factorability, internal consistency, and convergent validity were demonstrated. Discussion: The salience of newfound compassion after cancer was demonstrated. This research has important implications for accurately assessing the post-diagnosis trajectory of adjustment after cancer.