Oxaliplatin for Neoadjuvant CTRT for Rectal Cancer

In the JCO:

An initial report of a randomized trial looking at the addition of oxaliplatin to the standard 5FU based CTRT for neoadjuvant treatment for rectal cancer shows no difference in immediate pathologic outcomes, despite increased toxicity. While pCR rates might not be the whole story, this trial is another bucket of cold water on this approach for neoadjuvant treatment of rectal cancer.

Link and Abstract:

Primary Tumor Response to Preoperative Chemoradiation With or Without Oxaliplatin in Locally Advanced Rectal Cancer: Pathologic Results of the STAR-01 Randomized Phase III Trial [Gastrointestinal Cancer]: "Purpose

To investigate oxaliplatin combined with fluorouracil-based chemoradiotherapy as preoperative treatment for locally advanced rectal cancer.

Patients and Methods

Seven hundred forty-seven patients with resectable, locally advanced (cT3-4 and/or cN1-2) adenocarcinoma of the mid-low rectum were randomly assigned to receive pelvic radiation (50.4 Gy in 28 daily fractions) and concomitant infused fluorouracil (225 mg/m²/d) either alone (arm A, n = 379) or combined with oxaliplatin (60 mg/m² weekly x 6; arm B, n = 368). Overall survival is the primary end point. A protocol-planned analysis of response to preoperative treatment is reported here.

Results

Grade 3 to 4 adverse events during preoperative treatment were more frequent with oxaliplatin plus fluorouracil and radiation than with radiation and fluorouracil alone (24% v 8% of treated patients; P < .001). In arm B, 83% of the patients treated with oxaliplatin had five or more weekly administrations. Ninety-one percent, compared with 97% in the control arm, received ≥ 45 Gy (P < .001). Ninety-six percent versus 95% of patients underwent surgery with similar rates of abdominoperineal resections (20% v 18%, arm A v arm B). The rate of pathologic complete responses was 16% in both arms (odds ratio = 0.98; 95% CI, 0.66 to 1.44; P = .904). Twenty-six percent versus 29% of patients had pathologically positive lymph nodes (arm A v arm B; P = .447), 46% versus 44% had tumor infiltration beyond the muscularis propria (P = .701), and 7% versus 4% had positive circumferential resection margins (P = .239). Intra-abdominal metastases were found at surgery in 2.9% versus 0.5% of patients (arm A v arm B; P = .014).

Conclusion

Adding oxaliplatin to fluorouracil-based preoperative chemoradiotherapy significantly increases toxicity without affecting primary tumor response. Longer follow-up is needed to assess the impact on efficacy end points.

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