PURPOSE: Posttraumatic growth (PTG) has been recognized as beneficial for the emotional well-being of cancer patients. However, the longitudinal relationship between PTG and emotional distress remains unclear and has rarely been investigated among patients undergoing neoadjuvant therapy. We investigated the linear and quadratic longitudinal associations between distress (depression, anxiety, and negative affect) and PTG in lung cancer patients undergoing neoadjuvant immunotherapy. We also tested individual variations in the longitudinal associations. METHODS: Data were pooled from three clinical trials ( RESULTS: A unidirectional linear relationship was observed, with lower levels of distress predicting greater PTG over time. The impact of anxiety on PTG was more pronounced in patients with higher education or lower financial burdens, while the effect of negative affect was more salient in older patients. No significant quadratic effects of distress on PTG were observed. CONCLUSIONS: Lower emotional distress may facilitate the development of PTG over time. The longitudinal effect of distress on PTG varied on age, education, and financial burdens. IMPLICATIONS: Psychosocial interventions to promote PTG may be more effective by incorporating stress management and emotion regulation strategies, and need to be tailored to patients' socioeconomic characteristics.