# Find peritoneal spread while it is still small, and run complete cytoreduction through networks rather than adding heated chemotherapy

Source: https://onco.cc/ideas/idea-crc-peritoneal-disease-found-early-and-treated-in-networks/  
OnCo record `idea-crc-peritoneal-disease-found-early-and-treated-in-networks` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Bowel cancer that has seeded the lining of the abdomen responds badly to drugs but well to a complete operation, and the heated chemotherapy that everyone added turned out to do nothing. What decides the outcome is whether the disease is found while it is still limited and whether the patient reaches a centre that can remove all of it.

## Summary

Verwaal's randomised trial put median survival at 22.3 against 12.6 months with cytoreduction and heated intraperitoneal oxaliplatin, at 8 percent treatment-related mortality, and its own subgroup analysis showed the result belonged to patients with fewer than six of seven abdominal regions involved and to macroscopically complete resections. PRODIGE 7 then randomised the heated chemotherapy away in 265 patients who had all had complete cytoreduction: 41.7 against 41.2 months, hazard ratio 1.00, with more grade 3 complications at 60 days in the heated arm.

What that leaves is a surgical result gated by selection. Both trials enrolled patients under 70 with a Peritoneal Cancer Index of 25 or less; the index at presentation is the single strongest determinant of whether complete cytoreduction is possible, and it is a function of how early the peritoneal spread is found. Cross-sectional imaging is poor at low-volume peritoneal disease, and most of it is discovered at an operation done for another reason.

## Fields

- Kind: Idea
- Last checked: 2026-09-24
- Tags: colorectal-evidence
- Hypothesis: A structured surveillance pathway for patients at high risk of peritoneal recurrence (T4, perforated, mucinous or signet-ring primaries, positive peritoneal cytology) using ctDNA and diagnostic laparoscopy rather than cross-sectional imaging alone increases the proportion diagnosed with a Peritoneal Cancer Index below 10, and thereby the proportion undergoing complete cytoreduction, without increasing the number of futile laparotomies.
- Rationale: Complete cytoreduction, not the intraperitoneal chemotherapy, produces the survival; the Peritoneal Cancer Index at diagnosis determines whether complete cytoreduction is achievable; and current imaging misses low-volume peritoneal disease, so patients present past the threshold at which the one effective treatment can be offered.
- Proposed test: A randomised trial of structured surveillance with second-look laparoscopy and ctDNA against standard imaging follow-up in high-risk resected patients, with the proportion undergoing complete cytoreduction as the primary endpoint and overall survival, futile laparotomy rate and quality of life as secondary outcomes; networked referral so the operation happens in designated centres regardless of where surveillance occurs.
- Maturity: early-clinical
- Actor: clinic

## Sources

- Quénet et al.: PRODIGE 7 (Lancet Oncol 2021): https://europepmc.org/article/MED/33476595
- Verwaal et al.: cytoreduction and HIPEC (J Clin Oncol 2003): https://europepmc.org/article/MED/14551293

## Connected records

- roadmaps: [Colorectal cancer roadmap: from the adenoma-carcinoma sequence and the first screening trials to total mesorectal excision, oxaliplatin, RAS testing, immunotherapy for mismatch repair-deficient disease, ctDNA-guided treatment and organ preservation](https://onco.cc/roadmaps/colorectal-roadmap/), [Surgery roadmap: radical operations → less surgery → no surgery when a drug has done the work](https://onco.cc/roadmaps/surgery-roadmap/)
- cancers: [Colorectal cancer](https://onco.cc/cancers/colorectal/)
- fronts: [Diagnostics & Biomarkers](https://onco.cc/fronts/diagnostics/), [Surgery & Interventional](https://onco.cc/fronts/surgery/)
- technologies: [CT (computed tomography)](https://onco.cc/technologies/ct/), [HIPEC / PIPAC (intraperitoneal chemotherapy)](https://onco.cc/technologies/hipec/), [Liquid biopsy (ctDNA)](https://onco.cc/technologies/liquid-biopsy/), [MRD / molecular residual disease testing](https://onco.cc/technologies/mrd-testing/), [MRI](https://onco.cc/technologies/mri/)
- drugs: [FOLFOX (5-FU, leucovorin, oxaliplatin)](https://onco.cc/drugs/folfox/), [Oxaliplatin](https://onco.cc/drugs/oxaliplatin/)
- terms: [Circulating tumour DNA (ctDNA)](https://onco.cc/terms/ctdna/), [Minimal / molecular residual disease (MRD)](https://onco.cc/terms/mrd/)
- bottlenecks: [Failures are hidden](https://onco.cc/bottlenecks/b-negative-results/), [Fragmented care and guideline gaps](https://onco.cc/bottlenecks/b-care-fragmentation/), [Surgery and radiotherapy cure most, get least](https://onco.cc/bottlenecks/b-surgery-radiation-innovation/), [The hardest cancers are found late](https://onco.cc/bottlenecks/b-early-detection/)
- key papers: [Cytoreductive surgery plus hyperthermic intraperitoneal chemotherapy versus cytoreductive surgery alone for colorectal peritoneal metastases (PRODIGE 7)](https://onco.cc/key-papers/paper-quenet-prodige-7-hipec-peritoneal-colorectal-lancet-oncol-2021/), [Randomized trial of cytoreduction and hyperthermic intraperitoneal chemotherapy versus systemic chemotherapy and palliative surgery in patients with peritoneal carcinomatosis of colorectal cancer](https://onco.cc/key-papers/paper-verwaal-cytoreduction-hipec-peritoneal-colorectal-jco-2003/)

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