Oncologic Result as According to Tumor Regression Grade after Neoadjuvant Chemoradiation Therapy in Locally Advanced Rectal Cancer

ABSTRACT

PURPOSE: The effects of neoadjuvant chemoradiation therapy (NCRT) in cases of locally advanced rectal cancer include tumor downstaging with respect to a curative resection and a decreasing incidence of local recurrence. The aim of this study is to evaluate the oncologic results according to the tumor regression grade (TRG) after NCRT and radical surgical resection in cases of locally advanced rectal cancer. METHODS: From 1999 to 2003, 140 consecutive patients, who suffered from locally advanced rectal cancer (T3 or T4, or lymph node positive) were enrolled in this study. They all received neoadjuvant chemoradiation therapy and a radical resection. Chemotherapy was based on 5-fluorouracil (5-FU), and the total radiation dose was 5,040 cGy over 6 weeks. A radical surgical resection, including a total mesorectal excision, was done 6 to 8 weeks after the completion of NCRT. We classified patients into subgroups by using the TRG; then, we investigated the overall and the disease-free survival rates and the local recurrence and the distant metastasis rates. RESULTS: One hundred twenty-six (126, 90%) patients responded to radiation therapy. According to the TRG, the numbers of non- responders (Grade I, NR), partial responders (Grade II, PR), and patients who went into complete remission (Grade III, CR) were 14 (10%), 98 (70%), and 28 (20%), respectively. The overall survival (OS) and the disease-free survival (DFS) rates for 3 years (n=140) were 91.43% and 74.29%, and the rates for 5 years (n=117) were 81.20% and 67.52%, respectively. While there was no significant difference in the 3-year OS or DFS between the three groups stratified by TRG (P=0.1136, P=0.1215), the 5-year OS and DFS showed a statistical difference (P=0.0485, P=0.0458). Furthermore, the 3-year OS and DFS rates (P=0.0451, P=0.0458), as well as the 5-year OS and DFS rates (P=0.0139, P=0.0131) were significantly better for patients in the CR group than for the other patients. Still, no statistical significance differences existed between the CR group and the non-CR groups or between the TRG groups in terms of the local recurrence and the distant metastasis rates (P=0.447, P=0.271). CONCLUSIONS: Any tumor response group that shows complete Rremission after NCRT and radical surgical resection has an oncologic benefit in overall survival and disease- free survival in our study.