Addition of Oxaliplatin to Adjuvant Therapy for Late-Stage Colon Cancer Shows Benefit in Real-World Setting

Dr Hanna K. Sanoff

Adding oxaliplatin to conventional chemotherapy increases survival in patients with advanced colon cancer in a broad range of community practice settings, new data show.

Hanna K. Sanoff, MD, PhD, with the University of Virginia School of Medicine in Charlottesville, and colleagues elsewhere determined the overall survival of 4060 patients treated with oxaliplatin-containing versus non-oxaliplatin-containing adjuvant chemotherapy from five observational datasets from diverse treatment settings. The team compared its findings with pooled data from five randomized controlled trials (RCTs) enrolling a total of 8292 patients.

While RCTs have shown “unequivocally” that oxaliplatin-containing adjuvant therapy improves survival in patients with stage III colon cancer, fewer than 2% of patients with incident cancer were enrolled in these studies, Sanoff and associates observed. Also, patient populations in RCTs are much younger, healthier, and less racially and/or ethnically heterogeneous than the general population of cancer patients. As a result, it has not been known definitively whether this therapy boosts survival to the same degree in patients treated in the community as in patients treated as part of a RCT.

As in the RCTs, the present analysis was restricted to patients diagnosed before they were 75 years of age. All participants had stage III disease and had received chemotherapy within 120 days of surgery.

The analysis found that the addition of oxaliplatin to adjuvant chemotherapy was associated with “a consistent pattern of improved survival across the diverse practice settings,” the authors wrote. A statistically significant improvement in 3-year overall survival was observed in the Surveillance, Epidemiology, and End Results Registry linked to Medicare claims (SEER-Medicare), which was the largest database and included 2458 patients, and also in the New York State Cancer Registry linked to Medicare claims (NYSCR-Medicare), which included 446 patients (non-oxaliplatin-containing vs oxaliplatin-containing adjuvant therapy; adjusted hazard ratio [HR] of death; pooled RCTs: HR = 0.80; 95% CI, 0.70- 0.92; P =.002; SEER-Medicare: HR = 0.70; 95% CI, 0.60-0.82; P <.001; NYSCR Medicare patients aged ≥ 65 years: HR = 0.58; 95% CI, 0.38-0.90; P = .02).

Oxaliplatin’s survival advantage extended to older, sicker, and minority group patients.

Sanoff et al said that potential study limitations included the small sample size of racial and ethnic minorities and different follow-up duration among cohorts, the latter of which “challenged a unified interpretation.”

“

Physicians and patients should be reassured from our findings that oxaliplatin is associated with marginally but consistently superior survival for patients diagnosed before age 75 in community settings. ”

—Hanna K. Sanoff, MD, PhD

The investigators also said that it was not possible to rule out confounding based on patient selection as a substantial contributor to improved survival in oxaliplatin-treated patients.

“Physicians and patients should be reassured from our findings that oxaliplatin is associated with marginally but consistently superior survival for patients diagnosed before age 75 in community settings,” they said.

More than 100,000 Americans were diagnosed with colon cancer last year, and roughly one-third of them had stage III disease.

Sanoff HK, Carpenter WR, Martin CF, et al. Comparative effectiveness of oxaliplatin vs non-oxaliplatin-containing adjuvant chemotherapy for stage III colon cancer. J Natl Cancer Inst. 2012; 104(3):211-227.