Background: Little is known about the effect of granulocyte colony-stimulating factor (G-CSF) treatment during adjuvant chemotherapy on prognostic markers. The present study explored the association between G-CSF and changes in cancer antigen (CA)27.29 and circulating tumor cell (CTC) levels during therapy.
Patients and methods: A total of 3754 node-positive or high-risk node-negative early-stage breast cancer patients were treated within the SUCCESS-A trial (simultaneous study of gemcitabine-docetaxel combination adjuvant treatment, as well as extended bisphosphonate and surveillance-trial). CA27.29 and CTCs were determined before the start and within 6 weeks after the end of chemotherapy.
Results: Overall, 1324 of the 2646 patients (50.0%) available for analysis had ≥ 1 G-CSF applications during chemotherapy. G-CSF application was significantly associated with CA27.29 status before and after chemotherapy (χ2 = 30.6, df = 3; P < .001), because 238 patients (18.0%) with G-CSF treatment but only 146 (11.0%) without G-CSF treatment switched from a negative CA27.29 status before to a positive CA27.29 status after chemotherapy. In addition, patients with G-CSF application showed a significantly greater increase in CA27.29 levels after chemotherapy compared with patients without any G-CSF application during chemotherapy (Mann-Whitney U test; Z = -7.81, P < .001). No significant association was found between G-CSF application and CTC status before or after chemotherapy (χ2 = 1.2, df = 3; P = .75).
Conclusion: Cautious interpretation is needed regarding elevated levels of MUC-1-derived tumor markers such as CA27.29 shortly after adjuvant chemotherapy when G-CSF has been given, because G-CSF treatment was associated with increased CA27.29 levels after chemotherapy.
Keywords: Adjuvant chemotherapy; CTCs; Early breast cancer; G-CSF; Tumor marker flare up.
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