IDEA Study Prompted Change in Adjuvant Therapy for Colon Cancer

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The IDEA study has influenced the prescribing of adjuvant therapy for patients with stage III colon cancer, according to research published in the Journal of the National Comprehensive Cancer Network.1

Researchers conducted a real-world analysis of prescribing patterns for adjuvant therapy in patients with stage III colon cancer to determine if results from the IDEA study influenced practice.

IDEA was a pooled analysis of 6 randomized, phase 3 trials.2 It was conducted to determine if the duration of adjuvant therapy in stage III colon cancer could be reduced from 6 months to 3 months. Adjuvant therapy consisted of fluorouracil plus leucovorin and oxaliplatin (FOLFOX) or capecitabine plus oxaliplatin (CAPOX).

The 3-month treatment duration did not meet criteria for noninferiority to the 6-month treatment duration in the overall cohort (hazard ratio [HR], 1.07; 95% CI, 1.00-1.15).

When the researchers looked at results by treatment type, they found that 3 months of treatment was noninferior to 6 months in patients who received CAPOX (HR, 0.95; 95% CI, 0.85-1.06) but not in those who received FOLFOX (HR, 1.16; 95% CI, 1.06-1.26).

In the current analysis, the researchers evaluated whether these results altered adjuvant chemotherapy prescribing patterns in patients with stage III colon cancer from January 1, 2016, to January 31, 2021.1

The analysis included 399 patients. Most patients (68.4%) had a planned 6-month duration of treatment, but 31.6% had a planned 3-month duration of treatment.

There was a significant increase in the use of 3-month adjuvant chemotherapy from before the IDEA abstract was presented in June 2017 to after the full manuscript of IDEA was published in March 2018. Accordingly, the use of 6-month treatment decreased over that time period.

The use of 3-month treatment increased from 5.6% before the abstract was presented to 45.2% after the full manuscript was published (P <.001). The use of 6-month treatment decreased from 94.4% to 54.8% (P <.001).

The use of adjuvant FOLFOX decreased overall, from 86.0% before the abstract presentation to 52.0% after the full manuscript publication (P <.001). There was an increase in the use of FOLFOX for 3 months (3.7% to 10.0%; P <.001) and a decrease in the use of FOLFOX for 6 months (82.2% to 42.1%; P <.001).

The use of adjuvant CAPOX increased overall, from 14.0% before the abstract presentation to 48.0% after the full manuscript publication (P <.001). There was an increase in the use of CAPOX for 3 months (1.9% to 35.3%; P <.001) and an increase in the use of CAPOX for 6 months (12.1% to 12.7%; P <.001).

“Despite the IDEA collaboration failing to demonstrate noninferiority of 3 months’ duration of adjuvant therapy compared with 6 months, the findings have influenced practice prescribing patterns, favoring CAPOX and a shorter duration of planned adjuvant treatment,” the researchers summarized.

The team also found that the transition toward 3 months of chemotherapy was adopted earlier in Black patients than in White patients, as was the adoption of 3 months of CAPOX.

“One consideration may be racial and ethnic differences in the incidence of capecitabine-related toxicities; however, the findings are limited [due] to the small number of Black patients in our study,” the researchers wrote. “Our planned follow-up study will evaluate clinical outcomes in resected stage III colon cancer with adjuvant chemotherapy, including clinical outcomes associated with oxaliplatin discontinuation in a US-based patient population.”

Disclosures: One study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.


1. Ou F-S, Walden DJ, Larson JJ, et al. Changes in prescribing patterns in stage III colon cancer. J Natl Compre Canc Netw. Published online August 7, 2023. doi:10.6004/jnccn.2023.7028

2. Grothey A, Sobrero AF, Shields AF, et al. Duration of adjuvant chemotherapy for stage III colon cancer. N Engl J Med. 2018;378(13):1177-1188. doi:10.1056/NEJMoa1713709

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