Patients' preferences for 3 months versus 6 months of adjuvant chemotherapy (ACT) for colon cancer in the SCOT trial: what survival benefits make longer chemotherapy worthwhile?.

Background: The optimal duration of ACT following surgery for colon cancer remains controversial. SCOT is an international, randomised trial that compared 3 months versus 6 months of ACT in this setting. We sought the survival benefits that patients participating in SCOT judged necessary to make extra 3 months of ACT worthwhile. Method(s): SCOT participants from Australia & New Zealand completed a validated questionnaire 3 and 18 months after randomisation to elicit the minimum survival benefit each participant judged necessary to make it worthwhile having ACT for 6 months rather than 3 months. Standardised hypothetical scenarios used the following baseline survivals with 3 months of ACT: life expectancies (LE) of 5 years (5Y) and 15 years (15Y), and 5-year survival rates (5YS) of 65% and 85%. Comparisons were nonparametric, 2-sided, and considered statistically significant if p < 0.05. Result(s): Questionnaires were completed by 160 participants, 82 allocated 3 months ACT, and 78 allocated 6 months ACT. ACT was FOLFOX in 121 (75%), XELOX in 39 (25%), and the mean age was 64. Preferences varied substantially among participants, and did not differ according to the randomly allocated treatment group. The median survival benefits judged necessary to make the extra 3 months of ACT worthwhile were an extra: 3 years beyond a LE of 5Y; 3 years beyond a LE of 15Y; 15% beyond a 65% 5YS; and 5% beyond an 85% 5YS. Preferences were similar at 3 months and 18 months. Participants with symptomatic peripheral neuropathy (132, 82%) judged a median benefit of an extra 5% beyond a 65% 5YS necessary to warrant their symptoms. Conclusion(s): Participants' preferences varied substantially, and many judged much larger benefits needed to warrant having ACT for 6 months rather than 3 months than the estimates of the benefits based on the IDEA meta-analysis.