The usefulness of a three-protein signature blood assay (Mastocheck®) for follow-up after breast cancer surgery

Purpose Mastocheck®, a proteomic-based blood assay, has been developed for early diagnosis of breast cancer. The purpose of this study is whether Mastocheck® is useful as a postoperative follow-up. Methods A total of 255 patients were analyzed. The patients were classified into longitudinal monitoring and recurrence/nonrecurrence cohorts. The longitudinal monitoring cohort consisted of 111 patients. In this cohort, blood analyses were performed three times (before surgery, 8 weeks after surgery, and between 6 months and one year after surgery), and a comparative analysis of the values of Mastocheck® and individual proteins at each time point was performed. The recurrence/nonrecurrence cohort consisted of 144 patients who had been followed up for more than 1 year, and the blood marker values at the time of local recurrence were compared to those of nonrecurrence patients. Results In the longitudinal monitoring cohort analysis, in 81 of 111 patients were diagnosed with breast cancer with Mastocheck® and the sensitivity was 73.0%. Of 111 patients in the longitudinal monitoring cohort, 108 had two blood analyses (before and 8 weeks after surgery), and three serial blood analyses were performed on 53 patients. The Mastocheck® value that were in the cancer range of 73.0% (in 81 of 111 patients) of patients before surgery, was within the normal range of 68.5% (in 74 of 108 patients) at 8 weeks after surgery and 88.7% (in 47 of 53 patients) from 6 months to 1 year after surgery. The value of Mastocheck® was significantly decreased after surgery compared to before surgery ( p < 0.001). In the recurrence/nonrecurrence cohort analysis, the Mastocheck® values were in the cancer range in 38 out of 63 recurrence patients and within the normal range in 66 of 81 nonrecurrence patients (sensitivity of 60.3% and specificity of 80.2%). Conclusions Mastocheck® is expected to be used as a blood marker tool to aid in the early detection of recurrence during follow-up after breast cancer surgery.