The prevalence, operations, and outcomes of carcinoid heart disease

Late-stage diagnosis of carcinoid heart disease due to lack of access to health care

Carcinoid syndrome (CS) is a unique constellation of symptoms caused by release of vasoactive substances from neuroendocrine tumors (Pandit et al., StatPearls, 2022). Neuroendocrine tumors are rare with an annual incidence of 2 in 100,000 people (Ram et al., 46:21-27, 2019). Up to 50% of patients with these tumors will develop carcinoid syndrome, which is characterized by symptoms caused by elevated levels of serotonin and most commonly include fatigue, flushing, wheezing, and non-specific gastrointestinal symptoms such as diarrhea and malabsorption (Pandit et al., StatPearls, 2022) (Fox et.al., 90:1224-1228, 2004). Over time, patients with carcinoid syndrome can develop carcinoid heart disease (CHD). CHD refers to the cardiac complications that occur when the vasoactive substances, such as serotonin, tachykinins, and prostaglandins, secreted from the carcinoid tumors. These complications most commonly include valvular abnormalities, but can also present as coronary artery damage, arrhythmias or direct myocardial injury (Ram et al., 46:21-27, 2019). While CHD is not typically an initial feature of carcinoid syndrome, it does eventually occur in up to 70% of patients with carcinoid tumors (Ram et al., 46:21-27, 2019) (Jin et.al., 146:65-73, 2021) (Macfie et.al., 224:665-669, 2022). CHD is associated with significant morbidity and mortality due to the risk of progressive heart failure (Bober et.al., 14:1179546820968101, 2020). In this case, we describe a 35-year-old Hispanic woman in South Texas with undiagnosed carcinoid syndrome for over 10 years that eventually progressed to severe CHD. In this patient's case, we emphasize how lack of access to healthcare resulted in delay of diagnosis, appropriate treatment, and worsened prognosis in this young patient.

Carcinoid Syndrome: Preclinical Models and Future Therapeutic Strategies

Carcinoid syndrome represents a debilitating paraneoplastic disease, caused by the secretion of several substances, occurring in about 10-40% of patients with well-differentiated neuroendocrine tumors (NETs). The main signs and symptoms associated with carcinoid syndrome are flushing, diarrhea, hypotension, tachycardia, bronchoconstriction, venous telangiectasia, dyspnea and fibrotic complications (mesenteric and retroperitoneal fibrosis, and carcinoid heart disease). Although there are several drugs available for the treatment of carcinoid syndrome, the lack of therapeutic response, poor tolerance or resistance to drugs are often reported. Preclinical models are indispensable tools for investigating the pathogenesis, mechanisms for tumor progression and new therapeutic approaches for cancer. This paper provides a state-of-the-art overview of in vitro and in vivo models in NETs with carcinoid syndrome, highlighting the future developments and therapeutic approaches in this field.