Adjuvant chemotherapy for early colon cancer: what survival benefits make it worthwhile?

We sought to determine the minimum survival benefits that patients judged sufficient to make adjuvant chemotherapy for early colon cancer worthwhile, factors associated with these judgments; and, to compare a self-administered questionnaire with a validated, scripted interview.

One twenty three subjects who completed adjuvant chemotherapy for early colon cancer 3-60 months earlier completed a questionnaire; 97 were randomised to complete an interview before or after the questionnaire. Preferences were elicited by the time trade-off method in 4 hypothetical scenarios. Concordance between the interview and questionnaire was assessed with the intraclass correlation coefficient (ICC).

Median age was 65 years (range 19-86), 52% were female and 74% had involved lymph nodes. Over 60% of patients judged an additional 1 month beyond life expectancies of 5 years or 15 years, and an additional 1-2% beyond 5-year survival rates of 85% or 65%, sufficient to make chemotherapy worthwhile. Subjects with tertiary education (p=0.003) or aged 75 years or less (p=0.02) judged larger benefits necessary to make chemotherapy worthwhile. Concordance between the interview and questionnaire was high (ICCs 0.71-0.82).

Most subjects judged small survival benefits sufficient to make adjuvant chemotherapy worthwhile. A self-administered questionnaire was a valid and acceptable way of eliciting preferences.