Response rate and diagnostic accuracy of early PET-CT during
neo-adjuvant therapies in oesophageal adenocarcinoma: a systematic
review and meta-analysis
Abstract
Purpose Only 25% of oesophageal adenocarcinoma (OAC) patients have a
pathological response to neo-adjuvant therapy (NAT) before
oesophagectomy. Early response assessment using PET imaging may help
guide management of these patients. We performed a systematic review and
meta-analysis to synthesise the evidence detailing response rate and
diagnostic accuracy of early PET-CT assessment. Methods We
systematically searched several databases including MEDLINE and Embase.
Studies with mixed cohorts of histology, tumour location, and a repeat
PET-CT assessment after more than one cycle of NAT were excluded.
Reference standard was pathological response, defined by Becker or
Mandard classifications. Primary outcome was metabolic response rate
after one cycle of NAT defined by a reduction in maximum standardised
uptake value (SUVmax) of 35%. Secondary outcome was diagnostic accuracy
of treatment response prediction, defined as the sensitivity and
specificity of early PET-CT using this threshold. Quality of evidence
was also assessed. Random-effects meta-analysis pooled response rates
and diagnostic accuracy. This study was registered with PROSPERO
(CRD42019147034). Results Overall, 1341 articles were screened, and six
studies were eligible for analysis. These studies reported data for 518
patients (aged 27-78 years; 452 [87.3%] were male) between
2005-2020. Pooled sensitivity of early metabolic response to predict
pathological response was 77.2% (95%CI 53.2%-100%). Significant
heterogeneity existed between studies (I2=80.6% (95%CI 38.9%-93.8%),
p=0.006). Pooled specificity was 75.0% (95%CI 68.2%-82.5%), however
no significant heterogeneity between studies existed (I2=0.0% (95%CI
0.0%-67.4%), p=0.73). Conclusion High-quality evidence is lacking, and
few studies met the inclusion criteria of this systematic review. The
sensitivity of PET using a SUVmax reduction threshold of 35% was
suboptimal and varied widely. However, specificity was consistent across
studies with a pooled value of 75.0%, suggesting early PET assessment
is a better predictor of treatment resistance than of pathological
response. Further research is required to define optimal PET-guided
treatment decisions in OAC.