# Preoperative chemotherapy for colon cancer and short-term outcomes—a nationwide cohort study

## TL;DR

A nationwide study finds that preoperative chemotherapy for colon cancer does not increase short-term risks compared to immediate surgery, even for more advanced tumors.

## Contribution

The study provides population-based evidence on the safety of preoperative chemotherapy for colon cancer in a real-world setting.

## Key findings

- Preoperative chemotherapy did not increase 30- or 90-day mortality compared to upfront surgery.
- Patients receiving preoperative chemotherapy had higher rates of postoperative morbidity but similar anastomotic leakage rates.
- In cT4 tumors, short-term outcomes were comparable between preoperative chemotherapy and upfront surgery.

## Abstract

High-risk colon cancer may benefit from preoperative chemotherapy (preCHT), but evidence on its short-term safety and outcome is limited. Population-based evidence before its incorporation into national guidelines is lacking.

Patients with final weighted stage II–III colon cancer undergoing elective resection between 2007 and 2017 were identified in the Swedish Colorectal Cancer Registry. Patients planned for preCHT, irrespective of intention, were compared with those undergoing upfront surgery. Primary outcomes were 30- and 90-day mortality and 30-day major morbidity, defined as all medical and surgical complications classified as Clavien-Dindo (CD) ≥ 3 grade. Subgroup analyses examined cT4 disease, and multivariable logistic regression was performed.

Among 20,185 eligible patients, 299 (1.5%) received preCHT. Postoperative mortality was comparable (1.7% vs. 1.7%, p = 1.00 at 30 days and 3.0% vs. 2.8%, p = 0.82 at 90 days). Overall and surgical postoperative morbidity (CD ≥ 3) was higher in the preCHT group (34.1 vs. 25.0%, p < 0.001 and 17.4% vs. 13.1%, p < 0.001), rates of anastomotic leakage were similar (3.3% vs. 3.6%, p = 0.85). Compared to upfront surgery, the preCHT group was more likely to undergo multivisceral resections (53.9% vs. 13.6%, p < 0.001), with a higher rate of R1 resections (6.4% vs. 3.2%, p < 0.001), reflecting more advanced disease (cT4: 59.5% vs. 10.5%, p < 0.001; cN1-2: 54.9% vs. 28.6%, p < 0.001). In the cT4 subgroup, short-term outcomes were comparable, and regression analyses found no independent association between preCHT and mortality or major morbidity.

PreCHT appeared feasible in cT4N0-2M0 colon cancer, with short-term outcomes comparable to upfront surgery despite more advanced primary tumour and greater surgical extent.