Neuroendocrine neoplasms (NENs) represent a distinct and uncommon collection of tumors that originate from neuroendocrine cells found throughout the body, primarily in the gastroenteropancreatic (GEP) region and the bronchopulmonary system. In recent decades, the occurrence and frequency of NENs has consistently risen. NENs include a diverse array of neoplasms that vary from slowly growing, well-differentiated tumors to very aggressive carcinomas. The outlook and survival rates for patients with NENs differ significantly based on tumor location, grade, stage at diagnosis, functional status, and available treatment options. In recent years, the survival rates for patients with NENs appear to be on the rise. In the pathogenesis and progression of NENs, various crucial nonmodifiable factors should be regarded as vital determinants in the epidemiology and prognosis of these tumors. Among these, the most significant are age, gender, race/ethnicity, and family background, i.e., inherited syndromes. Additionally, lifestyle elements have gained significance in the overall development of cancer, including neuroendocrine neoplasms (NENs). Among these adjustable risk factors collectively known as lifestyle determinants, the most prominent are smoking behaviors, dietary choices, physical activity, occupational exposures, and air contamination.