CT assessment of early response to neoadjuvant therapy in colon cancer

Objectives:
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 MDCT, we report a significant reduction in tumour size, extramural tumour invasion, and number and size of
pathological regional lymph nodes following neoadjuvant treatment of locally advanced colon cancer. NEC may
induce not only tumour down-sizing, but may bring about a significant prolongation of disease-free survival and
eventually improve overall survival. The shown early response to NEC leads to hope for improvement in the
outcome of locally advanced colon cancer patients, and clinical follow-up data are warranted.