Abstract
BACKGROUND: The population of cancer survivors is growing. Some cancers and their treatments may lead to long-term adverse respiratory issues. This systematic review aims to summarise the evidence on the association between cancer survivorship and long-term respiratory health, across a range of cancer types. METHODS: We searched Cochrane, Embase and MEDLINE up until 23 February 2025 for cohort or nested case-control studies comparing incident respiratory outcomes in people with a history of cancer versus population-based cancer-free controls. We required studies to include follow-up time beyond the period of active cancer treatment. Outcomes included acute respiratory infections and chronic respiratory conditions. Study quality was assessed using The Scottish Intercollegiate Guidelines Network methodology checklists. RESULTS: We identified 34 eligible cohort studies. Cancer survivors' cohort sizes ranged from 1325 to >8 million. Only 4 out of 34 studies adjusted for smoking, leading to most studies being rated as low quality. Four of the 21 studies of acute respiratory infections were rated as acceptable/high quality, and of these, all observed raised risks, notably among survivors of haematological, head and neck, lung and oesophageal cancers. Of 19 studies of chronic respiratory conditions, 1 was rated as high quality, finding increased risks of chronic obstructive pulmonary disease (COPD) and pneumonitis in survivors of head and neck cancer. The remaining studies found increased risks of adverse outcomes from acute respiratory infections in 17 of 21 cancer types for which data were available, and of COPD in cervical, head and neck, lung, oesophageal, oral, stomach, thyroid and vulva cancers. DISCUSSION: These findings suggest increased risks of a range of respiratory conditions in survivors of some cancers. Much of the evidence is compromised by a lack of control for key potential confounders, like smoking. Future studies should address this limitation and investigate the drivers of respiratory risks in cancer survivors. Improved evidence could inform mitigation strategies and lead to better survivorship care plans. PROSPERO REGISTRATION NUMBER: CRD42022311557.