Based on our transnational studies and the work of other groups, indicating the metastasis-promoting effects of catecholamines (CAs) and prostaglandins (PGs) during the perioperative period (see below), we have conducted two biomarker clinical trials in breast cancer and in colorectal cancer (CRC) patients, testing the efficacy of attenuating adrenergic and COX2 signalling during the short perioperative period. We have now completed two clinical trials, including 3-year follow-up in CRC patients, and have obtained promising short-term outcomes of the drug treatment (propranolol and etodolac), including: (i) a high safety profile and minimal adverse effects on patients’ well-being, (ii) a reversal of epithelial-to-mesenchymal transition (EMT) and favourable changes in pro-metastatic and pro-inflammatory transcription factors in the excised breast/colon cancer tissue, and (iii) a trend towards improves 3-year DFS in CRC patients (p=.054) (large but statistically-insignificant improvement). Our studies are the first to test such a perioperative approach in cancer patients. Our findings have now been published in three peer-reviewed papers in prestigious journals and laid the foundation for conducting large clinical trials aiming to reduce recurrence rates and improve long-term cancer survival in several types of metastasizing cancers.