Systematic overview of preoperative (neoadjuvant) chemoradiotherapy trials in oesophageal cancer: evidence of a radiation and chemotherapy dose response.
OBJECTIVE
Numerous trials have shown that pathological complete response (pCR) following preoperative chemoradiotherapy (CRT) and surgery for oesophageal cancer is associated with improved survival. However, different radiotherapy doses and fractionations and chemotherapy drugs, doses and scheduling were used, which may account for the differences in observed pCR and survival rates. A dose-response relationship may exist between radiotherapy and chemotherapy dose and pCR.


METHODS
Trials using a single radiotherapy and chemotherapy regimen (5FU, cisplatin or mitomycin C-based) and providing information on patient numbers, age, resection and pCR rates were eligible. The endpoint used was pCR and the covariates analysed were prescribed radiotherapy dose, radiotherapy dosexdose per fraction, radiotherapy treatment time, prescribed chemotherapy (5FU, cisplatin and mitomycin C) dose and median age of patients within the trial. The model used was a multivariate logistic regression.


RESULTS
Twenty-six trials were included (1335 patients) in which 311 patients (24%) achieved pCR. The probability of pCR improved with increasing dose of radiotherapy (P=0.006), 5FU (P=0.003) and cisplatin (P=0.018). Increasing radiotherapy treatment time (P=0.035) and increasing median age (P=0.019) reduced the probability of pCR. The estimated alpha/beta ratio of oesophageal cancer was 4.9 Gy (95% confidence interval (CI) 1.5-17 Gy) and the estimated radiotherapy dose lost per day was 0.59 Gy (95% CI 0.18-0.99 Gy). One gram per square metre of 5FU was estimated to be equivalent to 1.9 Gy (95% CI 0.8-5.2 Gy) of radiation and 100mg/m2 of cisplatin was estimated to be equivalent to 7.2 Gy (95% CI 2.1-28 Gy). Mitomycin C dose did not appear to influence pCR rates (P=0.60).


CONCLUSIONS
There was evidence of a dose-response relationship between increasing protocol prescribed radiotherapy, 5FU and cisplatin dose and pCR. Additional significant factors were radiotherapy treatment time and median age of patients within the trial.
Geh
J Ian
JI
The Cancer Centre at the Queen Elizabeth Hospital, Birmingham, UK. ian.geh@uhb.nhs.uk
Bond
Simon J
SJ
Bentzen
Søren M
SM
Glynne-Jones
Robert
R
D017024:Chemotherapy, Adjuvant / Q000706:statistics & numerical data*; D002986:Clinical Trials as Topic / Q000706:statistics & numerical data*; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004938:Esophageal Neoplasms / Q000453:epidemiology* / Q000628:therapy*; D006801:Humans; D017063:Outcome Assessment, Health Care; D011300:Preoperative Care / Q000706:statistics & numerical data; D018714:Radiotherapy, Adjuvant / Q000706:statistics & numerical data*; D016896:Treatment Outcome