The following is a summary of “Preoperative Chemotherapy for Operable Colon Cancer: Mature Results of an International Randomized Controlled Trial,” published in the March 2023 issue of Oncology by Morton, et al.

For a study, researchers sought to evaluate the effectiveness of neoadjuvant chemotherapy (NAC) compared to standard postoperative chemotherapy for locally advanced colon cancer. 

Patients with radiologically staged T3-4, N0-2, M0 colon cancer were randomly allocated (2:1) to receive either six weeks of oxaliplatin-fluoropyrimidine preoperatively and 18 weeks postoperatively (NAC group) or 24 weeks postoperatively (control group). Patients with RAS-wildtype tumors could also be assigned 1:1 to receive panitumumab or not during NAC. The primary endpoint was residual disease or recurrence within two years. The study found that NAC was effective in producing marked T and N downstaging and histologic tumor regression. In addition, the patients in the NAC group had fewer incomplete resections and better two-year disease control than those in the control group. 

Out of the 699 patients who were given neoadjuvant chemotherapy (NAC), 96% (674) began the treatment, and 87% (606) completed it. Almost all NAC patients (98.1% or 686 out of 699) and 99.2% (351 out of 354) of the control group patients underwent surgery. While 4.3% of patients given NAC experienced obstructive symptoms and required expedited surgery, the treatment had fewer postoperative complications than the control group. The use of NAC resulted in significant downstaging of T and N and histologic tumor regression (all P < .001). Histopathologically complete resection was achieved more often in the NAC group than the control group, with percentages of 94% (648 out of 686) and 89% (311 out of 351), respectively (P-value < 0.001). Additionally, fewer patients in the NAC group than in the control group experienced residual or recurrent disease within two years, with percentages of 16.9% (118 out of 699) and 21.5% (76 out of 354), respectively. The rate ratio was 0.72 (95% CI, 0.54 to 0.98) with a P-value of 0.037. There was a strong correlation between tumor regression and freedom from recurrence. The use of panitumumab did not increase the benefits of NAC, while little benefit was seen in mismatch repair-deficient tumors. 

Finally, the study suggested that six weeks of NAC could be considered as a treatment option for locally advanced colon cancer, but little benefit was observed in mismatch repair-deficient tumors.

Reference: ascopubs.org/doi/full/10.1200/JCO.22.00046