No Significant Difference in Long-Term Survival With Mitomycin C vs Oxaliplatin for CRC Peritoneal Metastases

No significant overall survival (OS) disparity exists between the use of oxaliplatin and mitomycin C during hyperthermic intraperitoneal chemotherapy (HIPEC) for colorectal peritoneal metastases, according to long-term survival data from a nationwide registry in the Netherlands, data of which were presented at the virtual 2020 ESMO World Congress on Gastrointestinal Cancer.

“In the Netherlands, limited variability exists in the performance of cytoreductive surgery and HIPEC (CRS-HIPEC) among centers treating colorectal peritoneal metastases, except for the intra- peritoneal drug administration,” wrote Checca Bakkers, PhDc, Catharina Hospital, Eindhoven, Netherlands, and co-investigators, leading them to develop this study to investigate disparities in survival between the 2 most frequently used HIPEC regimens in >400 cancer centers worldwide, mitomycin-c and oxaliplatin.

“Previously published studies... have shown contradictory results and some studies were inconclusive. We still don’t know which regimen is superior in terms of prognosis for these patients,” Ms. Bakkers highlighted at the virtual 2020 ESMO World GI Congress on Gastrointestinal Cancer.

A total of 297 patients treated in the Netherlands between 2014 and 2017 were included in the study, retrieved from the Netherlands Cancer Registry. Out of 297 patients, 177 patients received mitomycin C and 120 received oxaliplatin. The only difference observed between the two arms was primary tumor location, with more left-sided colon in the oxaliplatin group (47.5% vs 33.3%, respectively).

The primary end point was OS. The effect of the intraperitoneal drug on OS was explored using multivariable Cox regression analysis.

The median OS was 30.7 months in the mitomycin C arm versus 46.6 months in the oxaliplatin arm. 1-year OS for patients treated with mitomycin C was 84.6% versus 85.8% in the oxaliplatin arm. The 2- and 3-year OS rates were 61.6% versus 63.9% and 44.7% versus 53.5% in the mitomycin C and oxaliplatin arms, respectively.

In the multivariable analysis, intraperitoneal drug was not observed to influence survival.

“We think this data are distinguishing from previously reported data as this is the first study to investigate the effects of mitomycin C versus oxalipatin in a nationwide data registry,” explained Ms Bakkers during the presentation, “and also, there is a large homogeneity among this group as all patients are treated according to the Dutch HIPEC protocol.

Researchers concluded no overall survival benefit could be determined of one regimen over the other so both mitomycin C and oxaliplatin are justified as chemotherapy regimens during HIPEC for colorectal peritoneal metastases.—Kaitlyn Manasterski

Bakkers C, Van Erning F, Rovers K, et al. Long-term survival after hyperthermic intraperitoneal chemotherapy using mitomycin C or oxaliplatin in colorectal cancer patients with synchronous peritoneal metastases: A nationwide comparative study. Presented at: the 22nd ESMO World Congress on Gastrointestinal Cancer; July 1-4, 2020; virtual. Abstract SO-29.