Lee, Mark

396 Background: The 12-gene Oncotype DXColon Cancer Assay is clinically validated as a predictor of recurrence risk in stage II colon cancer patients following surgery. We previously reported that the 12-gene assay led to 45% change in physician treatment (Tx) recommendations in a prospective study in MMR-P stage IIA colon cancer patients. Here, from the same prospective study, we report the influence of the 12-gene assay on patient Tx decisions, physician confidence, concordance in Tx choice between physicians and patients, and patient decisional conflict. Methods: Consecutive patients with resected stage IIA colon cancer who were candidates for adjuvant chemotherapy were enrolled by 105 physicians from 17 sites. Patient's tumor specimens were assessed by the 12-gene assay (RT-PCR) and MMR (IHC). Prior to and after receiving these results, patients completed surveys including (1) their Tx decisions (observation (Obs) vs. 5FU-monotherapy (5FU) vs. 5FU + oxaliplatin (Oxal)) and (2) indicators of decisional conflict. Results: 190 of 221 patients enrolled were evaluable including 139 who were MMR-P. Pre-assay: 46% of patients chose Obs, 3% 5FU, 7% Oxal, 2% other and 41% were undecided. Post-assay: 75% chose Obs, 12% 5FU, 11% Oxal, 3% other (undecided was not a possible response). Post-assay 129 (96%) of 135 definitive Tx decisions (Obs, 5FU, or Oxal) were concordant between patients and physicians compared to 49 (66%) of 74 definitive decisions pre-assay. In the majority of cases, patients (85%) and physicians (69%) reported that the assay influenced their Tx decisions. Assay results increased physician confidence in Tx recommendations in 126 (84%) and provided additional clinically relevant information to physicians in 129 (86%) of cases. Patient decisional conflict was significantly lower after assay results (p<0.001). Conclusions: In this prospective study, quantitative recurrence risk information provided by the 12-gene assay influenced Tx decisions for a majority of patients and physicians, increased physician confidence, improved concordance in Tx choice between patients and physicians and decreased patient decisional conflict.

Abstract Purpose. The Oncotype DX colon cancer assay is a clinically validated predictor of recurrence risk in stage II colon cancer patients. This prospective study evaluated the impact of recurrence score (RS) results on physician recommendations regarding adjuvant chemotherapy in T3, mismatch repair-proficient (MMR-P) stage II colon cancer patients. Patients and Methods. Stage IIA colon cancer patients were enrolled in 17 centers. Patient tumor specimens were assessed by the RS test (quantitative reverse transcription-polymerase chain reaction) and mismatch repair (immunohistochemistry). For each patient, the physician's recommended postoperative treatment plan of observation, fluoropyrimidine monotherapy, or combination therapy with oxaliplatin was recorded before and after the RS and mismatch repair results were provided. Results. Of 221 enrolled patients, 141 patients had T3 MMR-P tumors and were eligible for the primary analysis. Treatment recommendations changed for 63 (45%; 95% confidence interval: 36%–53%) of these 141 T3 MMR-P patients, with intensity decreasing for 47 (33%) and increasing for 16 (11%). Recommendations for chemotherapy decreased from 73 patients (52%) to 42 (30%), following review of RS results by physician and patient. Increased treatment intensity was more often observed at higher RS values, and decreased intensity was observed at lower values (p = .011). Conclusion. Compared with traditional clinicopathological assessment, incorporation of the RS result into clinical decision making was associated with treatment recommendation changes for 45% of T3 MMR-P stage II colon cancer patients in this prospective multicenter study. Use of the RS assay may lead to overall reduction in adjuvant chemotherapy use in this subgroup of stage II colon cancer patients.