BackgroundLocal relapse and peritoneal carcinomatosis (PC) for pT4 colon cancer is estimated in 15,6% and 36,7% for 12 months and 36 months from surgical resection respectively, achieving a 5 years overall survival of 6%. There are promising results using prophylactic HIPEC in this group of patients, and it is estimated that up to 26% of all T4 colon cancer could benefit from this treatment with a minimal morbidity. Adjuvant HIPEC is effective to avoid the possibility of peritoneal seeding after surgical resection. Taking into account these results and the cumulative experience in HIPEC use, we will lead a randomized controlled trial to determine the effectiveness and safety of adjuvant treatment with HIPEC vs. standard treatment in patients with colon cancer at high risk of peritoneal recurrence (pT4).Methods/DesignThe aim of this study is to determine the effectiveness and safety of adjuvant HIPEC in preventing the development of PC in patients with colon cancer with a high risk of peritoneal recurrence (cT4). This study will be carried out in 15 Spanish HIPEC centres. Eligible for inclusion are patients who underwent curative resection for cT4NxM0 stage colon cancer. After resection of the primary tumour, 200 patients will be randomized to adjuvant HIPEC followed by routine adjuvant systemic chemotherapy in the experimental arm, or to systemic chemotherapy only in the control arm. Adjuvant HIPEC will be performed simultaneously after the primary resection. Mitomycin C will be used as chemotherapeutic agent, for 60 min at 42–43 °C. Primary endpoint is loco-regional control (LC) in months and the rate of loco-regional control (%LC) at 12 months and 36 months after resection.DiscussionWe assumed that adjuvant HIPEC will reduce the expected absolute risk of peritoneal recurrence from 36% to 18% at 36 months for T4 colon-rectal carcinoma.Trial registrationNCT02614534 (clinicaltrial.gov) Nov-2015.

ImportancePeritoneal metastasis in patients with locally advanced colon cancer (T4 stage) is estimated to recur at a rate of approximately 25% at 3 years from surgical resection and is associated with poor prognosis. There is controversy regarding the clinical benefit of prophylactic hyperthermic intraperitoneal chemotherapy (HIPEC) in these patients.ObjectiveTo assess the efficacy and safety of intraoperative HIPEC in patients with locally advanced colon cancer.Design, Setting, and ParticipantsThis open-label, phase 3 randomized clinical trial was conducted in 17 Spanish centers from November 15, 2015, to March 9, 2021. Enrolled patients were aged 18 to 75 years with locally advanced primary colon cancer diagnosed preoperatively (cT4N02M0).InterventionsPatients were randomly assigned 1:1 to receive cytoreduction plus HIPEC with mitomycin C (30 mg/m2 over 60 minutes; investigational group) or cytoreduction alone (comparator group), both followed by systemic adjuvant chemotherapy. Randomization of the intention-to-treat population was done via a web-based system, with stratification by treatment center and sex.Main Outcomes and MeasuresThe primary outcome was 3-year locoregional control (LC) rate, defined as the proportion of patients without peritoneal disease recurrence analyzed by intention to treat. Secondary end points were disease-free survival, overall survival, morbidity, and rate of toxic effects.ResultsA total of 184 patients were recruited and randomized (investigational group, n = 89; comparator group, n = 95). The mean (SD) age was 61.5 (9.2) years, and 111 (60.3%) were male. Median duration of follow-up was 36 months (IQR, 27-36 months). Demographic and clinical characteristics were similar between groups. The 3-year LC rate was higher in the investigational group (97.6%) than in the comparator group (87.6%) (log-rank P = .03; hazard ratio [HR], 0.21; 95% CI, 0.05-0.95). No differences were observed in disease-free survival (investigational, 81.2%; comparator, 78.0%; log-rank P = .22; HR, 0.71; 95% CI, 0.41-1.22) or overall survival (investigational, 91.7%; comparator, 92.9%; log-rank P = .68; HR, 0.79; 95% CI, 0.26-2.37). The definitive subgroup with pT4 disease showed a pronounced benefit in 3-year LC rate after investigational treatment (investigational: 98.3%; comparator: 82.1%; log-rank P = .003; HR, 0.09; 95% CI, 0.01-0.70). No differences in morbidity or toxic effects between groups were observed.Conclusions and RelevanceIn this randomized clinical trial, the addition of HIPEC to complete surgical resection for locally advanced colon cancer improved the 3-year LC rate compared with surgery alone. This approach should be considered for patients with locally advanced colorectal cancer.Trial RegistrationClinicalTrials.gov Identifier: NCT02614534