CLO19-023: Induction Chemotherapy Followed by Chemoradiation and Trans-Anal Full Thickness Local Excision or Total Mesorectal Resection in Patients With T2-T3/NO-N+ Adenocarcinoma of the Rectum; Preliminary Results of Phase 2 Prospective Clinical Trial
Background: The National Comprehensive Cancer Network (NCCN) Guidelines recently recognized total neoadjuvant therapy (TNT) as an acceptable option in patients with T3 and any N rectal cancer. Previous studies suggested that patients who received chemotherapy prior to conventional preoperative chemoradiation (CRT) and surgery allowed patients to receive more of their planned treatment with a better toxicity profile and increase in pathological response. However, those studies used a long course of FOLFOX or used capecitabine and oxaliplatin as an induction regimen. We are conducting a phase 2 prospective clinical trial to evaluate the use of 6 cycles of FOLFOX as TNT in patients with T2-T3/N0-N+. Patients and Methods: Patients with T2-T3/N0-N+ enrolled on our phase 2 prospective trial were included for this analysis. Patients received 6 cycles of FOLFOX (infusional fluorouracil, leucovorin, and oxaliplatin), which was administered every 2 weeks. After 3 weeks of recovery period, patients then received conventional CRT with 5FU or capecitabine. All patients got MRI and endorectal ultrasound (ERUS) at baseline, after completing FOLFOX 3-months regimen and after finishing conventional CRT. Patients underwent either full-thickness local excision or total mesorectal resection depending on their tumor response to neoadjuvant therapy. The time interval between completion of radiation therapy and surgery ranged between 7and 12 weeks. Results: A total of 10 patients completed the chemotherapy and CRT treatment regimen. 9 patients proceeded to surgery and the 10th patient is scheduled for surgery. Clinical downstaging by MRI or ERUS was shown in 9 of 10 patients with only 6 cycles of FOLFOX. Complete clinical response was achieved in 6 patients as evident by ERUS/MRI of the pelvis after 3 months of FOLFOX before CRT. Complete pathological response was found in 4 of 9 patients (44%). In addition, 4 other patients had significant albeit not complete pathological response. Conclusions: This study suggests that adding only 6 cycles of neoadjuvant FOLFOX before CRT improved clinical and pathological downstaging of T2-T3/N0-N+ rectal adenocarcinoma and may facilitate organ preservation surgery. This is strategy needs to be investigated in larger phase III trials to validate these findings.