Endocrine Abstracts

Introduction: The aetiology of NENs vary; some are sporadic, others familial. An association between index NENs of the mid gut (ileum and colon) with subsequent colorectal primaries has been reported.

Aim: We determined to evaluate the relationship between the diagnosis of an index primary malignancy and subsequent diagnosis of NEN.

Methods: A population-based retrospective cohort study was under taken for persons with NEN diagnosis in England between 1st January 2013 and 31st December 2015, using data collected by Public Health England National Cancer Registration and Analysis Service (NCRAS). NENs were defined by the WHO 2015 classification, excluding diffuse pulmonary neuroendocrine hyperplasia. All multiple primary malignancies captured from 1965 to present were identified; tumours diagnosed pre-NEN, post-NEN and synchronous. Multiple logistic regression was used to determine the odds ratio to approximate relative risk of those diagnosed with a NEN, by site, in England between 2013 and 2015 being previously exposed to cancer, adjusting for age and sex.

Results: 12.844 persons were diagnosed with a NEN in England in the specified time period. Many had multiple primaries; 16.225 tumours were diagnosed in the cohort overall, including NENs and non-NENs (excluding benign tumours and basal cell carcinomas). 2.805 (21.8%) patients had at least one metachronous or synchronous cancer, 81% of which had an index primary before the 2013–2015 diagnosis of a NEN, 12% a primary subsequent to NEN, and 7% with a synchronous other primary. The most common sites for metachronous cancer primaries were prostate (14%), breast (13%), non-melanoma skin cancer excluding Merkel cell carcinomas (12%) and colon (11%). Significant associations were found between many NEN and index primaries: colorectal NEN and prostate, kidney, and testis index primaries; small intestine NENs, prostate and female reproductive organs, kidney and upper GI; and pancreas NEN and kidney, prostate, breast, colorectal, upper GI, thyroid and index primaries.

Discussion: One in five people with NENs may experience secondary malignancies in their lifetime. This association study highlights the requirement for tumour surveillance and counselling of people with NEN. Improvements in cancer registry data will enable survival analysis for longer time periods.