Chapter 1 - Epidemiology, risk factors and pathogenesis
Oesophageal cancer (OC) comprises two distinct diseases: oesophageal squamous cell carcinoma (OSCC) and oesophageal adenocarcinoma (OAC), each with different risk factors and incidence trends.
OC is the eighth most common cancer worldwide.
Whereas OSCC incidence is declining, the incidence of OAC is rising in developed countries, such as Canada, USA (White population) and Scotland.
Latin American countries, Asia, and Black populations of the USA have the highest incidence of OSCC, particularly in the ‘OC belt’ (Northern China to Northern Iran).
Precursor dysplastic lesions are detectable for OAC/OSCC. Repeated exposure to high-temperature drinks or gastro-oesophageal reflux disease (GORD) may cause inflammation.
Barrett’s oesophagus (BE) is a probable intermediate stage between GORD and OAC, in which squamous cells are replaced by columnar epithelial cells, due to chronic injury.
OACs arise from glandular cells at the lower end of oesophagus. OSCCs arise from epithelial cells that are exposed to irritation and carcinogens in foods and drinks.
Smoking, low fruit and vegetable intake and high intake of processed meat increase the risk of both OSCC and OAC. Alcohol consumption only increases the risk of OSCC.
Hot beverages increase the risk of both. Human papillomavirus (HPV) 16 infection may increase the risk of OSCC, while Helicobacter pylori (H. pylori) infection may reduce the risk of OAC. Obesity, GORD and BE increase the risk of OAC.
Genome-wide association studies (GWAS) of OSCC in Chinese populations showed associations with different single nucleotide polymorphisms (SNPs). The Cancer Genome Atlas (TCGA) showed genomic amplification of different chromosomes.
- Are there geographical differences in the distribution of the two histological types of OC?
- Are there differences in the risk factors associated with OAC and OSCC?
- Is alcohol consumption associated with the risk of both OAC and OSCC?