Study design and participants: The study was a prospective open-label randomized controlled trial of adding Aspirin to Epirubicin, Oxaliplatin, Capecitabine (EOX) in locally advanced and metastatic gastric cancer from November 2017 till May 2019 with a minimum follow-up period of 6 months from the date of randomization. The patients included in the study were inoperable locally advanced and metastatic gastric cancer of 18 to 70 years with a Performance status (ECOG-PS ≤ 2, who could take oral medications. Patients with significant organ dysfunction such as those with ejection fraction less than 50%, serum creatinine >2 mg/dl, serum bilirubin >1.5 mg/dl, AST /ALT >3 X ULN, ALP >5 X ULN, Thromboytopenia less than 1 lakh/µL, previous history of aspirin intake and aspirin hypersensitivity were excluded from the study.
The primary objective of the study was to compare the efficacy of the combination of Aspirin plus Epirubicin, Oxaliplatin, Capecitabine (EOX) versus EOX alone on response rates in patients with locally advanced and metastatic inoperable gastric cancer. The secondary objectives were to study the adverse effects, progression-free survival, and overall survival among both the groups. The primary endpoint was overall response rates in the per-protocol group defined as patients who received a minimum of 3 cycles and had an evaluable response after randomization. The secondary endpoints included toxicity analysis, Progression-free survival, and Overall survival.
Sample size calculation and randomization: The sample size was estimated using the statistical formula for the comparison of 2 independent proportions. The minimum expected difference in the proportion of patients concerning response rates between the two groups was taken as 0.3 (30%). The sample size was estimated at a 5% level of significance and 80% power. Accounting for a dropout rate of 10%, a final sample size of 110 was planned, with 55 in each arm.
Patients were randomly assigned to a 1:1 ratio to receive standard EOX (group 1) or EOX with Aspirin (group 2). This was an open-label study. Randomization was done using a computer-generated fixed block size. Allocation concealment was done using sequentially numbered, opaque sealed envelopes.
Statistical analysis: The continuous data were expressed as mean with S.D. or median with range. The categorical data comparison was carried out using the Chi-square test or Fisher's exact test. The continuous data between groups were carried out by independent t-test, Mann Whitney U test, Kaplan Meier product estimates were used to estimate survival functions, and the log-rank test was used to compare survival function between the groups. Covariates associated with survival function were analyzed by using Cox proportional hazards model. Statistical analysis was carried out using IBM SPSS Statistics for Windows, version 19 (IBM Corp., Armonk, N.Y., USA)
Baseline Characteristics:
Patient data were collected using a standardized case record proforma thorough medical history, detailed physical examination, a complete blood count, routine biochemistry(renal and liver function tests), viral markers (HIV I and II,anti-HCV, HBsAg),2D ECHO, ECG, upper G.I. endoscopy and biopsy, baseline imaging by CECT thorax, abdomen and pelvis.
Chemotherapy:
Group1 - EOX in standard schedule (Epirubicin 50 mg/m2 iv bolus, D1 oxaliplatin 130 mg/m2 iv infusion over 2 hours D1 &Capecitabine 625 mg/m2 BD orally days 1-21 q 3 weekly for 8 cycles . Group 2 patients received EOX as mentioned above plus aspirin 150 mg O.D. daily till disease progression [6]. The new cycle was started when the absolute neutrophil count was greater than 1500/mm3 and platelet count greater than 100000/mm3. Aspirin dose was withheld if the platelet counts were less than 50000/mm3.
Methodology and definition of endpoints:
Tumor measurements were performed at baseline and after 3-4 cycles of chemotherapy and then every 3 months until progression by the radiologist who was blinded to treatment arms according to RECIST 1.1 criteria [7]. CBR ( Clinical benefit rate) or DCR ( Disease control rate) was taken as the percentage of patients in each arm who had a complete response (C.R.), Partial response (P.R.), or stable disease (S.D.). Overall response rate (ORR) was taken as that percentage of patients with a complete or partial response. PFS (progression-free survival) was defined as the time from randomization to first progression or death. O.S. (overall survival) was defined as the time from randomization to date of death due to any cause or date of last follow-up ( censored) if the patient was lost to follow up.
The study was approved by the Institute's ethical committee (JIP/IEC/2016/1069). Written informed consent was obtained from each participant in their vernacular language (Tamil, English). The trial was registered in CTRI (Clinical trial registry of India) (CTRI no. CTRI/2017/11/010651).