At ASCO a number of studies showed the efficacy data of combining 5-FU or Xeloda with oxaliplatin in combination with radiation therapy in patients with rectal cancer.
Based on a German study published a couple of years ago, chemoradiation became the standard therapy for patients with resectable rectal cancer. The rate of sphincter-sparing surgeries and lower toxicities were the reason to prefer chemoradiation prior to surgery instead of adjuvant treatment after surgery.
Over the last couple of years many studies aimed to improve the efficacy of neoadjuvant chemoradiation therapies by intensifying the chemotherapy. Standard therapy is 5-FU or Xeloda® (capecitabine). By adding oxaliplatin it was hoped that the success rate of chemoradiation could be increased.
Success of neoadjuvant radiation is measured by a complete pathological response rate (complete disappearance of cancer cells). With 5-FU or Xeloda that can be reached in about 10-15% of the cases. Smaller studies have suggested that the addition of oxaliplatin could double the rate.
However the studies presented at ASCO a couple of weeks ago (ACCORD) did not show any significant difference when oxaliplatin was added. However there was interestingly a lower risk of developing metastases in the patients who received the additional oxaliplatin therapy. These findings may question the ongoing R-04 study which compares 5-FU to 5-FU plus oxaliplatin in combination with radiation therapy.
In the Southwest Oncology Group (SWOG) we have choosen another way. In the study just opened, we started with Xeloda, oxaliplatin and Erbitux (kras wild type), then we continue with the chemo and add radiation to have a both powerful systemic effect and a local effect.