A. M. Dinaux1,2, R. Amri1,2, L. Bordeianou1,2, H. Kunitake1,2, D. L. Berger1,2 1Massachusetts General Hospital,Surgery,Boston, MA, USA 2Harvard School Of Medicine,Surgery,Brookline, MA, USA
Introduction:
Neoadjuvant chemoradiation has been shown to reduce local recurrence in rectal cancer. It also can reduce the size of large tumors simplifying surgical resection. However, this is an expensive regimen with long-term side effects. Overstaging patients leads to unnecessary treatment. Understaging leads to delaying systemic chemotherapy as radiation therapy is usually done prior to systemic treatment postoperatively. Complicating this decision making process, is fact that we have now started to observe complete responders who have been shown to have similar outcomes with or without surgery. This abstract analyzes rectal cancer patients who were understaged and their subsequent outcomes.
Methods:
This abstract compared rectal adenocarcinoma patients who underwent surgical resection in a single center from 2004 through 2014, with either clinical stage I disease with tumor positive nodes on postoperative pathology, or neoadjuvantly treated clinical stage III patients. Patients who had a local excision were excluded.
Results:
Thirty-three clinically stage I had nodal disease on postoperative pathology (cN0 pN+). These patients had worse rates of EMVI (33.3% vs. 14.5%; P=0.008), perineural invasion (39.4% vs. 16.9%; P = 0.003), large vessel invasion (30.3% vs. 13.5%; P = 0.014), and small vessel invasion (48.5% vs. 15%; <0.001), than pathological stage III patients who underwent neoadjuvant therapy. Adjuvant chemotherapy rates were comparable (clinically stage I: 78.8% vs. clinically stage III: 80.7%; P = 0.800), whereas adjuvant radiotherapy rates were unsurprisingly higher in the clinically stage I group (54.5% vs. 1.4%; P<0.001). Local and distant recurrence rates were not significantly different, while rectal cancer death in clinically stage I patients was 12.1%, compared to 9.2% in the clinically stage III group (P=0.594).
Conclusion:
Clinically stage I patients who were pathologically stage III had more aggressive disease than neoadjuvantly treated clinical stage III patients. The long-term outcomes also point towards a trend with increased mortality in the understaged patients. This underlines the importance of neoadjuvant therapy and accurate staging preoperatively, which is essential to avoid understaging and therefore undertreatment of pathological stage III patients.