Views of Australian Medical Oncologists Regarding the Use of Mismatch Repair Status to Assist Adjuvant Chemotherapy Recommendations for Patients With Early-Stage Colon Cancer.

Background: Mismatch repair deficiency (dMMR) has been shown to confer a superior prognosis and is possibly predictive of a lack of benefit from fluoropyrimidine adjuvant chemotherapy (AC) for early-stage colon cancer (ESCC). We conducted a survey to assess medical oncologists' views regarding ESCC AC, with an emphasis on the use of MMR status to guide their recommendations.

Materials And Methods: The survey was distributed to all members of the Medical Oncology Group of Australia. Their demographic data, practice information, and views on the use of MMR status in ESCC and in 3 case scenarios were collected. The 3 case scenarios were a 68-year-old woman with moderate-risk stage II disease, who was eager to undergo AC (case 1); a 43-year-old woman with high-risk stage II disease, who was ambivalent regarding AC (case 2); and a 78-year-old woman with multiple comorbidities and high-risk stage II disease, who was eager to undergo AC.

Results: The survey response rate was 35% (190 of 550). Of the 190 responders, 152 (80%) routinely treated patients with colon cancer (CC) and completed the survey. For patients with stage II CC, 112 of 141 (79%) would use MMR status to assist AC recommendations, and 97 (69%) thought it changed their practice. In the case scenarios, 81% (case 1, 110 of 136), 67% (case 2, 92 of 137), and 43% (case 3, 57 of 133) used MMR status to assist AC recommendations. If dMMR was present, 78% (case 1, 86 of 110), 53% (case 2, 49 of 92), and 53% (case 3, 30 of 57) changed their initial recommendations by advising against AC.

Conclusion: The use of MMR status to assist AC recommendations for patients with stage II CC is an accepted practice for most Australian medical oncologists who responded to our survey.