At the European Society of Medical Oncology (ESMO) 2017 congress, data from a tertiary referral centre (The Christie NHS Foundation Trust, Manchester, UK) were presented on the outcomes of 139 patients with carcinoid syndrome, identified from 882 patients treated for a gastroenteropancreatic neuroendocrine tumour (NET).
Carcinoid syndrome is a combination of signs and symptoms, such as skin flushing, diarrhoea, bronchospasm, and fibrotic valvulopathy, resulting from advanced NET secreting active mediators, such as serotonin and kallikrein.1 Treating manifestations of the disease and preventing complications, in addition to achieving tumour control, can prove challenging. Due to the rarity of NET and carcinoid syndrome, there are few studies that present real-world data from large patient populations.
The prevalence of carcinoid syndrome reported in this presentation (16%) was similar to that indicated by Halperin et al.2 (19%) in the 1st large epidemiological study, focussing on data from the American Surveillance, Epidemiology, and End Results (SEER) database linked to Medicare claims, in the field of NET. The frequencies of cardinal carcinoid symptoms in patients seen at The Christie NHS Foundation Trust were slightly higher than in previous reports,3,4 but, similarly, flushing and diarrhoea were by far the most common and were both present in 91% of patients, while carcinoid heart disease was described in 35% of patients.
Carcinoid syndrome is usually associated with liver metastases because of the hepatic clearance of active mediators released into the bloodstream by a primary tumour in the gastroenteropancreatic tract;3 however, 18 patients (13%) in this study did not have liver metastases. Possible explanations for this are the influence of portacaval anastomoses; metastases in organs not drained by the portal circulation, such as lung (2 patients) and ovary metastases (1 patient); and the presence of occult liver metastases.
There was a positive association between the symptomatic and biochemical response to treatment, assessed through measurement of baseline and during treatment levels of 5-hydroxyindoleacetic acid (5-HIAA) in the serum or urine. Patients were divided into three groups correlating with symptom control: symptoms normalised on treatment, partial symptom control, and no symptomatic benefit. For all treatment lines, it was possible to ascertain that patients who achieved partial (p=0.049, p=0.001, respectively) and total symptom control (both p<0.001) for flushing and diarrhoea had a greater decline in 5-HIAA levels after treatment initiation than patients with no improvement in symptoms. However, changes in 5-HIAA levels 6 months after treatment initiation were not prognostic for progression-free (PFS) or overall survival (OS). Nevertheless, improvements in symptoms may positively impact quality of life; however, this element could not be assessed in this retrospective study.
Median follow-up was 45.7 months and revealed a median PFS of 27.0 months and OS of 65.4 months, similar to results reported by Halperin et al.2 (OS: 60 months). Most patients (92%) were offered somatostatin analogues during their disease course, with high proportions undergoing liver embolisation (30%) or debulking surgery (23%). Surgery in the palliative setting is indicated in patients with carcinoid syndrome to aid symptom control and to prevent obstructive complications of a primary bowel tumour. Indeed, primary in situ was a negative prognostic factor for OS on multivariable analysis (hazard ratio [HR] 2.23; p=0.03). Other independent prognosticators were high expression of Ki-67 antigen (HR: 1.06; p=0.049) for worse PFS and baseline 5-HIAA levels for both PFS and OS (HR: 1.03; p=0.001 and HR: 1.02; p=0.04, respectively).
This is, to the best of our knowledge, one of the largest cohorts to date of real-world patients with gastroenteropancreatic NET and carcinoid syndrome from a single tertiary referral centre to have been analysed for clinical features and prognostic factors, and should inform future trial design in this rare subgroup.