The kinetic profile and clinical implication of SCC-Ag in squamous cervical cancer patients undergoing radical hysterectomy using the Simoa assay: a prospective observational study

Background: To study the kinetic profile and clinicopathological implications of squamous cell carcinoma antigen (SCC-Ag) in cervical cancer patients who underwent surgery by a self-developed SCC-Ag single molecule assay (Simoa) prototype immunoassay.

Methods: Participants were prospectively enrolled between 04/2016 and 06/2017. Consecutive serum samples were collected at five points: day 0 (the day before surgery), postoperative day 4, weeks 2-4, months 2-4 and months 5-7. In total, 92 patients and 352 samples were included. The kinetic change in SCC-Ag levels and their associations with clinicopathological characteristics were studied.

Results: Simoa SCC-Ag was validated by comparison with the Architect assay. SCC-Ag levels measured by the Simoa assay were highly correlated with the Architect assay's levels (Pearson's correlation coefficient = 0.979, Passing-Bablok regression slope 0.894 (0.847 to 0.949), intercept - 0.009 (- 0.047 to 0.027)). The median values for each time-point detected by the Simoa assay were 2.49, 0.66, 0.61, 0.72, and 0.71 ng/mL, respectively. The SCC-Ag levels decreased dramatically after surgery and then stabilized and fluctuated to some extent within 6 months. Patients with certain risk factors had significantly higher SCC-Ag values than their negative counterparts before surgery and at earlier time points after surgery, while no difference existed at the end of observation. Furthermore, although patients with positive lymph nodes had sustained higher SCC-Ag levels compared to those with negative lymph nodes, similar kinetic patterns of SCC-Ag levels were observed after surgery. Patients who received postoperative treatment had significantly higher SCC-Ag values than those with surgery only at diagnosis, while no difference existed after treatment.

Conclusions: The Simoa SCC-Ag prototype was established for clinical settings. The SCC-Ag levels were higher in patients with risk factors, whereas the kinetic trend of SCC-Ag might be mainly affected by postoperative adjuvant therapy. These data indicate that the SCC-Ag level might be a good predictor for the status of cervical cancer, including disease aggressiveness and treatment response.