LAUSR

Introduction: Lung cancer is the commonest cause of cancer deaths worldwide. Treated cancer patients are at high risk for lung cancer from shared epidemiological factors (e.g. smoking, chemotherapy or radiotherapy). The risk of a second, smoking related cancer after lung cancer resection reaches ~25% by 5 years. We sought to study the risk of second (lung) cancer in our patients. Methods: An electronic health records search identified patients with two or more cancer diagnoses between 2008-2018 in a tertiary cancer centre (catchment ~60,000 diagnoses/yr). For lung cancer diagnosis as a second event, we recorded time to lung cancer, histological subtype, treatment and survival. Results: 5473 patients had two cancer diagnoses: 867 (16%) had lung cancer - lung cancer was the first cancer in 152 patients and second cancer in 715 patients. The commonest cancer types to develop lung cancer were breast (25%), prostate (17%), bladder (6%) colon (5%), basal cell (4%), larynx/trachea (3%), pharynx/tonsil (3%) cancers. Median time to lung cancer diagnosis: breast (11.0), prostate (4.4), bladder (3.3), colon (3.3), basal cell (6.0), Larynx and trachea (3.6) in years. Dominance of lung squamous vs. adenocarcinoma and survival rates differed by first cancer type. Conclusions: In patients with two cancers, lung cancer is usually the second event, presumably due to comorbidity, survival and our unique population e.g. radical vs adjuvant or palliative intent. The commonest first cancers were breast and prostate. Prostate, bladder and colon cancer developed lung cancer earlier than breast cancer. These data help to inform which cancer types are likely to develop lung cancer and influence tumour surveillance strategies.