Impact of Patient Age and Comorbidity on Surgeon Versus Oncologist Preferences for Adjuvant Chemotherapy for Stage III Colon Cancer

Background

To study surgeons' versus oncologists' preferences for adjuvant chemotherapy for elderly patients with stage III colon cancer, as population studies indicate that such patients are less likely to receive treatment.

Study Design

A vignette-based survey was mailed to a nationally representative sample of 1,000 general surgeons and 1,000 oncologists in the United States. Patient age, comorbidity level, and preference were varied across eight vignettes. Physician preference for referral (surgeons) or treatment (oncologists) was measured using a 7-point Likert scale. Mixed-effects linear regression was used to evaluate the results.

Results

One thousand twenty-nine surveys were returned (response rate of 54%). Among surgeons, increasing age and more severe comorbidity resulted in lower likelihood of referral to oncologist: mean difference in preference scores for vignettes describing a 61-year-old versus an 83-year-old patient (adjusted for comorbidity) was 0.77 (p < 0.0001); mean difference in scores between vignettes describing a patient with none versus severe comorbidity, adjusted for age, was 1.94 (p < 0.0001). Among oncologists, patient age and comorbidity interacted significantly (p < 0.0001) to affect oncologists' preferences: both increasing age and more severe comorbidity resulted in decreased preference for recommending adjuvant chemotherapy, but oncologists were more heavily influenced by comorbidity at younger patient age. Patient preference against therapy also affected physicians' recommendations (p < 0.0001), but the magnitude of effect was small relative to age and comorbidity.

Conclusion

Patient age and comorbidity level influence both types of physicians' preferences about adjuvant chemotherapy for colon cancer and might explain some of the patterns of care seen for this disease in population-based studies.