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

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 beta-subunit of human chorionic gonadotropin (beta-hCG).

PATIENTS AND METHODS

Peripheral blood was sampled from 49 patients with breast cancer before operation (d(-1)), 1 day after operation (d(1)), and 7 days after operation (d(7)). Total RNA was extracted from peripheral blood mononuclear cells, followed by RT-PCR assay. The products for beta-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), d(1), and d(7) were 8.2, 20.4, and 10.2%, respectively. For beta-hCG, the corresponding results were 12.2, 26.5, and 16.3%, respectively. There was a higher positive rate in d(1) samples than in d(-1) samples for CK19 and beta-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.