Adjuvant Systemic Chemotherapy Tied to Better Survival After Resection of Colorectal Peritoneal Metastases

By Will Boggs MD

August 04, 2020

NEW YORK (Reuters Health) - Adjuvant systemic chemotherapy following resection of isolated synchronous colorectal peritoneal metastases is associated with improved survival compared with active surveillance, according to a new study.

"We anticipated a shorter disease-free survival without adjuvant treatment, but as we thought that these patients would have more remaining options for palliative systemic treatment in case of recurrence, we did not anticipate finding a large difference in overall survival between (the two) strategies," said Dr. Ignace H. J. T. de Hingh of Catharina Cancer Institute, in Eindhoven, the Netherlands.

"However, as the study shows, we did find a significant and clinically relevant difference in survival," he told Reuters Health by email.

It remains unclear whether patients with isolated synchronous colorectal peritoneal metastases should receive adjuvant systemic chemotherapy. Such therapy is not recommended by Dutch guidelines, unlike some other national and international guidelines, Dr. de Hingh and colleagues note in JAMA Oncology.

The team used data from the Netherlands Cancer Registry to assess the association between adjuvant systemic chemotherapy and overall survival in 393 patients who underwent upfront complete cytoreductive surgery with hypothermic intraperitoneal chemotherapy (CRS-HIPEC).

Overall, 172 patients (44%) received adjuvant systemic chemotherapy for a median 21 weeks, beginning a mean eight weeks after CRS-HIPEC.

In a propensity-score-matched analysis of 142 pairs of patients, the median overall survival was 39.2 months in the adjuvant systemic chemotherapy group versus 24.8 months in the active surveillance group.

Overall survival rates were 92% at one year, 55% at three years and 35% at five years in the group receiving adjuvant systemic chemotherapy, compared with rates of 81%, 41% and 22%, respectively, in the group on active surveillance.

Adjuvant systemic chemotherapy was associated with a significant 36% reduction in the risk of death, compared with active surveillance.

"Although we tried to statistically correct for bias in receiving adjuvant chemotherapy in this study, residual bias may still have played an important role," Dr. de Hingh cautioned. "The study should thus not be taken as the definitive proof for the effectiveness of adjuvant chemotherapy in these patients. Besides, other issues, such as quality of life (which may be lower in patients receiving systemic chemo), were not investigated."

"However, in the absence of data from randomized studies, this study may be taken into account when counseling patients who are considering adjuvant chemotherapy after surgical treatment," said Dr. de Hingh, adding that, "Currently all treatment is based on very limited evidence and expert opinion only."

He noted, "In the Netherlands, a nationwide multicenter randomized controlled trial (CAIRO6) is currently investigating the role of perioperative systemic treatment in these patients. The phase-2 part investigating feasibility and safety was recently completed, and we are now recruiting patients in the phase-3 part investigating efficacy."

SOURCE: JAMA Oncology, online July 16, 2020.