Computed tomography assessment of early response to neoadjuvant therapy in colon cancer

Introduction: Using multidetector computed tomography, we aimed to assess the early response of neoadjuvant drug therapy for locally advanced colon cancer. Methods: Computed tomography with IV contrast was acquired from 67 patients before and after up to three cycles of preoperative treatment. All patients had histologically confirmed colon cancer, a T4 or T3 tumour with extramural invasion >= 5 mm and no distant metastases or peritoneal nodules. The patients were treated with oxaliplatin and capecitabine. In addition, those with no mutations in the KRAS, BRAF and PIK3CA genes were also treated with panitumumab. Before and after treatment, we measured the tumour diameter in two different planes, the extension of the extramural tumour invasion, and the number and size of enlarged lymph nodes. Results: The mean tumour length was 7.8 cm (95% confidence interval (CI): 5.3-10.4) at baseline and 4.34 cm (95% CI: 4.0-4.9) after treatment. The mean extramural tumour invasion was 10.6 mm (95% CI: 9.5-11.8) at baseline and 5.7 mm (95% CI: 4.7-6.7) after treatment. The mean number of enlarged lymph nodes was 4.1 (95% CI: 3.4-4.9) at baseline and 2.1 (95% CI: 1.4-2.7) after treatment. According to RECIST 1.1, 45% (95% CI: 34-57) of the patients had a response and 55% (95% CI: 43-67) had stable disease. None of the patients showed progressive disease. Conclusion: Using CT, we demonstrated a significant reduction in tumour size, extramural tumour invasion, number and size of enlarged lymph nodes following neoadjuvant treatment.