Multicenter Assessment of Postoperative Mastocheck^® Dynamics Following Curative Breast Cancer Surgery

Previous single-institution studies reported postoperative decreases in Mastocheck^® values following breast cancer surgery. This study aimed to assess the reproducibility of these postoperative changes using two independent clinical cohorts with distinct postoperative assessment designs.

Postoperative Mastocheck^® dynamics were evaluated in two independent cohorts with distinct postoperative assessment designs. In the CHA Gangnam Medical Center (CHA University/CHA Medical Center, Seoul, Republic of Korea) cohort, Mastocheck^® values obtained before surgery were compared with postoperative values preoperative values (n = 210) were compared with an independent postoperative set obtained ≥6 months after surgery (n = 171; median 378 days), and a paired subset (n = 28) was analyzed for within-patient changes. In an independent cohort from Myongji Hospital, only postoperative patients were enrolled, and longitudinal Mastocheck^® measurements were analyzed in patients with four consecutive postoperative assessments. Changes in Mastocheck^® values and transitions across the predefined diagnostic cut-off (0.0668) were evaluated.

In the CHA cohort, Mastocheck^® values were significantly lower in the postoperative set than in the preoperative set (p < 0.001). Within the paired subset, among patients above the cut-off preoperatively (n = 20), 90.0% (18/20) converted to below the cut-off postoperatively, and paired analysis confirmed a significant postoperative decrease (Wilcoxon signed-rank test, two-tailed, p = 1.72 × 10^-4). In the Myongji cohort, longitudinal follow-up demonstrated a sustained decline in Mastocheck^® values over time, accompanied by a stepwise reduction in the proportion of patients exceeding the cut-off, reaching 0% at the final follow-up.

Across two independent cohorts with complementary postoperative assessment strategies, Mastocheck^® values consistently decreased after breast cancer surgery and shifted to, or were maintained below, the predefined diagnostic cut-off. These findings reproduce and extend prior single-institution observations, supporting the reproducibility of Mastocheck^® postoperative decline dynamics and cut-off transitions across independent cohorts. This study did not evaluate recurrence detection, imaging concordance, or survival outcomes, and therefore does not establish clinical surveillance performance.