Downstaging Without Complete Pathologic Response After Neoadjuvant Treatment Improves Cancer Outcomes for cIII but not cII Rectal Cancers

The aim of this study was to evaluate whether downstaging impacts prognosis in patients with cII versus cIII rectal cancer. We identified from our colorectal cancer database 295 patients with primary cII and cIII rectal cancer staged by CT and ERUS/MRI who received 5-FU-based chemoradiation followed by R0 surgery after a median interval of 7 weeks during 1997–2007. The median radiotherapy dose was 5040 cGy. We excluded 58 patients with pathologic complete response (pCR) and compared among the remaining 162 patients pathologic downstaging (cII to ypI, cIII to ypII or ypI) versus no pathologic downstaging (c stage ≤ yp stage). Outcomes evaluated were 5-year overall survival, 3-year cancer-specific survival, disease-free survival, overall recurrence, local recurrence, and distant recurrence. The median age was 58 years and median follow-up was 48 months. Patients with downstaging versus no downstaging were statistically comparable with respect to demographics, chemoradiation regimen, interval time between neoadjuvant chemoradiation and surgery, tumor distance from anal verge, surgical procedures performed, and follow-up time. With the exception of local recurrence rates, downstaging resulted in significantly improved cancer outcomes for cIII but not cII. Downstaging without pCR is a significant prognostic factor for patients with stage cIII rectal cancer. Tumor response to neoadjuvant chemoradiation should be taken into account when defining the optimal adjuvant chemotherapy regimen for patients with cIII rectal cancer.