Neoadjuvant Capecitabine and Oxaliplatin Before Concurrent Capecitabine and Radiation in Locally Advanced Rectal Cancers: Experience of a Cancer Hospital in Pakistan.

Purpose: To report the toxicity and pathologic response rates after adding neoadjuvant capecitabine and oxaliplatin (CAPOX) followed by concurrent radiation and capecitabine (CAPRT) and surgery in patients with locally advanced rectal cancer.

Materials And Methods: We retrospectively analyzed medical records of 301 patients between January 2007 and December 2014. Patients were treated with four cycles of neoadjuvant chemotherapy comprising CAPOX, followed by radiotherapy at doses of 45-54 Gy in 25-30 fractions with concurrent capecitabine. A response assessment scan was performed at 4-6 weeks postradiation followed by surgical evaluation at 6-8 weeks. Pathologic tumor and nodal response rates as well as circumferential resection margin were assessed on surgical specimens.

Results: The median age of the patients was 43 years (range, 16-78). Overall, 227 (75.4%) patients were able to complete four cycles of CAPOX. Neoadjuvant chemotherapy was well-tolerated with no serious adverse effects. The most common toxicity was diarrhea (grade 2, n = 108; 35.8%; grade 3, n = 57; 18.9%; grade 4, n = 25; 8.3%) followed by neuropathy (grade 2, n = 132; 43.8%; grade 3, n = 54; 17.9%) and oral mucositis (grade 2, n = 108; 35.8%; grade 3, n = 47; 15.6%; grade 4, n = 9; 2.99%). A total of 229 (76.1%) patients underwent surgery. Pathologic complete response was seen in 52 (22.7%; 95% CI, 13 to 28), whereas 200 (87.3%; 95% CI, 82 to 99) patients had a negative circumferential resection margin on pathology.

Conclusion: Neoadjuvant chemotherapy with CAPOX before CAPRT and planned total mesorectal excision surgery result in good tumor regression and substantial pathologic complete response rates with acceptable toxicity. With growing interest in organ preservation in rectal cancer, the strategy of completing all chemotherapy and chemoradiotherapy before planned surgery offers a favorable paradigm. However, further randomized clinical trials are needed to support this evidence.