No Evidence That Smiling and Laughing Improve Cancer Survival
Based on the most authoritative guideline evidence available, laughter therapy has inconclusive evidence for improving outcomes in cancer patients, and there is no consistent evidence that psychological coping strategies, including laughter, increase or decrease cancer survival rates 1, 2.
What the Guidelines Tell Us
The 2023 Society for Integrative Oncology-ASCO guideline explicitly states there is inconclusive evidence for laughter therapy to improve anxiety or depression symptoms in people with cancer, regardless of when in the course of care the intervention is provided 1. This is the highest quality guideline evidence available on this topic.
More importantly, a 2020 ASCO guideline on coping in palliative care definitively states: "No consistent evidence demonstrates that psychological coping increases or decreases the risk of cancer recurrence or survival" 2. This directly addresses your question about survival outcomes.
What Laughter Therapy May Actually Help With
While laughter doesn't affect survival, it may have some limited benefits:
- Quality of life improvements: One small study showed laughter therapy improved quality of life and resilience in breast cancer survivors, though it did not significantly affect depression or immune responses 3
- Stress reduction: A 2003 study found laughter reduced self-reported stress and potentially improved natural killer cell activity in healthy women, though this was not in cancer patients and did not measure survival 4
- Immune markers: A small Japanese trial suggested laughter therapy might improve some immune markers in chemotherapy patients, but this did not translate to survival outcomes 5
Critical Limitations and Caveats
The research on laughter therapy suffers from major methodological flaws:
- Small sample sizes (studies ranged from 33 to 41 participants)
- No standardization of the intervention
- Lack of active control conditions
- No measurement of actual survival outcomes
- Studies measured surrogate markers (immune cells, stress levels) rather than what matters: mortality, morbidity, and long-term quality of life
The Bottom Line for Clinical Practice
Do not recommend laughter therapy as a cancer treatment intervention with any expectation of improving survival. While it may provide some psychological comfort and is unlikely to cause harm, there is no evidence it affects cancer outcomes that matter—survival, disease progression, or recurrence 1, 2.
If patients ask about laughter therapy, you can acknowledge it may help with stress management and quality of life in the moment, but be clear it will not change their cancer prognosis. Focus instead on evidence-based interventions like mindfulness-based interventions and yoga for managing anxiety and depression symptoms, which have stronger evidence 1.