Prevalence of esophageal squamous dysplasia in relatives of patients with esophageal cancer in Southwestern Kenya

1Introduction

Esophageal cancer is the sixth most common cause of cancer death in the world [1] . The two epithelial subtypes are esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma [2] . The burden of disease varies greatly in different geographic regions, with certain areas being endemic for ESCC [13] . ESCC remains the dominant histologic type in many low- and middle-income countries 345 . In East Africa, esophageal cancer is the third most common cancer in males and females [1] .

ESCC is the most common cancer diagnosis at Tenwek Hospital in southwestern Kenya, where it accounts for 35% of new cancer diagnoses [6] . Tenwek Hospital is a 361-bed, faith-based referral center for endoscopy and surgery. One striking feature observed in the surrounding population is that 8% of esophageal cancer patients are less than 30 years of age [6] . The causes of esophageal cancer in southwestern Kenya are unclear.

Esophageal squamous dysplasia (ESD) is the asymptomatic precursor lesion of ESCC, and the risk of subsequent cancer increases depending on the degree of dysplasia [7] . In an endemic region in China, the prevalence of ESD was found to be around 30% in asymptomatic high-risk Chinese populations [89] . In a prior population-based cross-sectional investigation, the Study of Tenwek hospital Esophageal dysplasia Prevalence (STEP) study, the prevalence of ESD in asymptomatic Kenyans who live near Tenwek Hospital was 14.4% (95% CI: 10–19%) [10] . ESD can be detected by Lugol’s iodine chromoendoscopy or narrow-band imaging with subsequent directed biopsy 111213 . During Lugol’s chromoendoscopy, normal esophageal mucosa stains darkly with iodine, while regions of ESD and some areas of severe esophagitis appear as “unstained lesions” (USLs) [1011] .

Esophageal cancer is a highly fatal disease. One reason for this high mortality is that precursor and early invasive lesions are usually asymptomatic, and most patients present late when their tumors are inoperable. Thus, prevention and early detection and treatment are highly desirable to prevent the high mortality associated with ESCC. Primary prevention may be achievable through modifying environmental risk factors associated with the disease, and early detection and treatment of early lesions may be achievable through population screening in high-risk areas. In Asia, screening programs to detect and treat asymptomatic ESD have been shown to reduce cancer mortality 141516 .

Because of the common occurrence of young ESCC cases seen at Tenwek Hospital, and our previous finding that 43% of ESCC patients younger than 30 years of age reported a family history of ESCC [17] , we hypothesized that there might be a familial predisposition to ESD in southwestern Kenya [18] . We performed this study to determine the prevalence of ESD in first-degree relatives of esophageal cancer patients in this area, and to compare this prevalence with that of the general population in the same geographical region, which we previously studied [10] . If first-degree relatives have a higher rate of ESD, they may require targeted screening. We also aimed to explore the impact of various risk factors on the prevalence of ESD among first-degree relatives of patients with ESCC.