Introduction Patients with neuroendocrine neoplasms (NENs) may often develop other malignancies. This study aimed to identify the frequency at which these second malignancies occurred in England. Methods Data was extracted from the National Cancer Registration and Analysis Service (NCRAS) on all patients diagnosed with a NEN at one of eight NEN site groups between 2012-2018: appendix, caecum, colon, lung, pancreas, rectum, small intestine and stomach. WHO International Classification of Disease edition 10 (ICD-10) codes were used to identify patients who had been diagnosed with an additional non-NEN cancer. Standardised incidence ratios (SIRs) for tumours diagnosed after the index NEN were produced for each non-NEN cancer type by sex and site. Results A total of 20,579 patients were included in the study. The most commonly occurring non-NEN cancers after NEN diagnosis were prostate (20%), lung (20%) and breast (15%). Statistically significant SIRs were observed for non-NEN cancer of the lung (SIR=1.85, 95%CI:1.55-2.22), colon (SIR=1.78, 95%CI:1.40-2.27), prostate (SIR=1.56, 95%CI:1.31-1.86), kidney (SIR=3.53, 95%CI:2.72-4.59) and thyroid (SIR=6.31, 95%CI:4.26-9.33). When stratified by sex, statistically significant SIRs remained for lung, renal, colon and thyroid tumours. Additionally, females had a statistically significant SIR for stomach cancer (2.65, 95%CI:1.26-5.57) and bladder cancer (SIR=2.61, 95%CI:1.36-5.02). Discussion/Conclusion This study found that patients with a NEN experienced a metachronous tumour of the lung, prostate, kidney, colon and thyroid at a higher rate than the general population of England. Surveillance and engagement in existing screening programmes is required to enable earlier diagnosis of second non-NEN tumours in these patients.

The Author(s). Published by S. Karger AG, Basel