Surgery‐related shedding of breast cancer cells as determined by RT‐PCR assay

Abstract

Background and Objectives Surgery could result in the shedding of cancer cells into the circulation. These cells were investigated with reverse transcriptase‐polymerase chain reaction (RT‐PCR) assay for cytokeratin 19 (CK19) and β‐subunit of human chorionic gonadotropin (β‐hCG). Patients and Methods Peripheral blood was sampled from 49 patients with breast cancer before operation (d₋₁), 1 day after operation (d₁), and 7 days after operation (d₇). Total RNA was extracted from peripheral blood mononuclear cells, followed by RT‐PCR assay. The products for β‐hCG were digested with Sty I endonuclease. The patients were followed up for a median of 33 months for signs of recurrence and metastasis. Results The results for CK19 at d₋₁, d₁, and d₇ were 8.2, 20.4, and 10.2%, respectively. For β‐hCG, the corresponding results were 12.2, 26.5, and 16.3%, respectively. There was a higher positive rate in d₁ samples than in d₋₁ samples for CK19 and β‐hCG (P < 0.05 and P = 0.092, respectively). Conversions of signals from being negative to positive were found in all stages. These did not demonstrate a statistical correlation with prognostic factors associated with a poor prognosis. Only two of the five recurrence occurred in the 15 patients with the signal conversions, while the other three occurred in the patients showing no signals in all samples. Conclusions Cancerous breast cells that enter into the blood circulation as a result of an operation are unlikely to be involved in the formation of metastatic deposits. J. Surg. Oncol. 2003;82:228–232.