摘要
BACKGROUND The incidence of oesophageal adenocarcinoma(OAC)has been reported to be increasing in many countries.Alongside this trend,an increase in incidence of early-onset OAC,defined as OAC in adults aged under 50 years,has been observed.It is unclear whether survival outcomes for early-onset OAC patients differ from older age groups.AIM To investigate survival outcomes in early-onset OAC patients.METHODS Ovid Medline and Embase were searched from inception to January 2022 for relevant studies relating to early-onset OAC and survival outcomes.Results regarding the overall five-year survival and risk of death of younger and older patients with OAC were extracted and pooled using meta-analyses to produce pooled estimates and 95%CIs where possible.RESULTS Eleven studies which compared survival of early-onset OAC,defined as age at diagnosis of<50 years,with older patients were included.A narrative review of median and mean survival demonstrated conflicting results,with studies showing early-onset OAC patients having both better and worse outcomes compared to older age groups.A meta-analysis of five-year survival demonstrated similar outcomes across age groups,with 22%-25%of patients in the young,middle and older age groups alive after five years.A meta-analysis of four studies demon-strated that early-onset OAC patients did not have a significantly increased risk of death compared to middle-aged patients(hazard ratio 1.12,95%CI:0.85-1.47).INTRODUCTION There is concern that the incidence of oesophageal adenocarcinoma(OAC)in patients under 50,described as early-onset OAC,is increasing.However,data regarding survival of younger patients with OAC is sparse.Globally,while increasing age remains a major non-modifiable risk factor for cancer,the incidence of early-onset cancers,largely accepted to be in adults aged under 50 years,is increasing[1].This includes an observed increase in the incidence of gastrointestinal malignancies such as colorectal,oesophageal,gastric and hepatobiliary cancers[2-4].Despite oesophageal squamous cell carcinoma(OSCC)being more common globally(88%of cases)[5],a striking increase in oesophageal OAC incidence has been reported in developed countries,such as the United States and Europe[6,7].Worryingly,the United Kingdom has the highest incidence of OAC cases in the world[8].In addition to the increase in OAC,an increase in incidence of early-onset OAC,defined as OAC in adults aged under 50 years,has been observed[9,10].A population-based cohort in the Netherlands,consisting of 59584 patients,demonstrated the incidence of early-onset OAC to have tripled from 1989 to 2018,while OSCC cases declined in this age group[7].OAC usually develops in the lower third of the oesophagus and the gastro-oesophageal junction,with risk factors including obesity and gastro-oesophageal reflux disease[11].A poor prognosis is observed,with the overall five-year survival rate for oesophageal cancer between 15%-20%,even with treatment[12,13].These low survival rates are likely due to a combination of late diagnosis,intrinsic resistance to systemic therapy and the limited efficacy of surgical resection.Younger patients tend to present at a more advanced stage at diagnosis compared to those diagnosed later in life.A single centre,retrospective study found that 33.3%of patients in the younger age category(<50 years old)presented with stage IV OAC,compared to the 20.6%of the oldest age category(>70 years old)[14].Another population-based study in the Netherlands observed that OAC patients under 50 years old also presented with distant metastasis more often in comparison to older patients(50.5%vs 44.7%),and that tumour differentiation also varied between age groups[15].Reports of survival estimates in patients with early-onset OAC compared with older patients have resulted in contrasting findings to date.Some studies report that due to the advanced stage and aggressiveness of the tumours seen that the prognosis of these patients is almost always worse than their older counterparts[16].In contrast,another study found that the overall survival,as well as stage-specific survival was higher in those who were younger[17].A Dutch study which included only resectable cases found no difference in 5-year disease specific survival[18].Given the conflicting evidence to date,the aim of this systematic review was to investigate survival in OAC patients according to age at diagnosis.A protocol was composed,and the reporting of this systematic review designed,using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines[19].The protocol included:The review question,search strategy,inclusion criteria,type of quality assessment,the strategy for data analysis,and the‘population,intervention,comparator,and outcome’criteria.These are expanded below.
