# Short‐Term Results of the SONCAR Study: Optimized Neoadjuvant Chemoradiotherapy in Locally Advanced Rectal Cancer Patients

## TL;DR

This study found that adding oxaliplatin to standard treatment improved tumor response in rectal cancer patients, especially those with tumors near the anal verge.

## Contribution

The study demonstrates that adding oxaliplatin to chemoradiotherapy increases complete tumor response rates in locally advanced rectal cancer.

## Key findings

- The experimental group had a higher pathological complete response rate (31.9%) compared to the control group (21.5%).
- Tumor regression was significantly greater in the experimental group for tumors within 5 cm of the anal verge.
- The addition of oxaliplatin showed manageable toxicity while improving tumor response.

## Abstract

This research endeavored to ascertain whether four cycles of oxaliplatin in conjunction with standard radiation (oxaliplatin‐CRT) could enhance overall survival when compared with standard neoadjuvant chemoradiotherapy (nCRT) in locally advanced rectal cancer (LARC). A Phase III randomized trial (SONCAR Trial, NCT02031939) was conducted in China, involving patients diagnosed with clinical T3‐4 and/or N+ rectal cancer. Patients were randomly allocated to the experimental arm (receiving pelvic radiation (50 Gy/25 fractions) in conjunction with oxaliplatin and capecitabine) or the control arm (pelvic radiation in conjunction with capecitabine alone). The main endpoint was a 5‐year OS, while the secondary objectives encompassed pathological complete response (pCR), 3‐year disease‐free survival, and surgical complications. A total of 536 patients were assessable. The rate of pCR was notably higher in the experimental group (31.9%) than in the control group (21.5%) (p = 0.008). The clinical complete response (cCR) rate was also higher in the experimental group (p = 0.024). Among patients with tumors located within 5 cm of the anal verge, the experimental group exhibited a significantly greater tumor regression, with rates of 33.8% compared to 21.6% in the control group (p = 0.024). In summary, oxaliplatin‐CRT significantly augmented the tumor response in LARC patients with manageable toxicity.

This study investigates whether adding four cycles of CapOX to standard neoadjuvant chemoradiotherapy improves overall survival in patients with locally advanced rectal cancer. The results show that this combination significantly increases complete tumor response rates, particularly for tumors close to the anal verge, with manageable toxicity.