Bromodeoxyuridine labeling for S-phase measurement in breast carcinoma

Abstract

Background. The S‐phase fraction relates to proliferation, an important determinant of tumor behavior, and has been measured most accurately with the DNA precursor tritiated thymidine (TT). The TT labeling index (LI) is a strong stage‐independent prognostic indicator for breast carcinoma. The thymidine analogue 5‐bromodeoxyuridine (BrdU) is also incorporated into DNA and has the advantage over TT of immunohistochemical detectability rather than requiring autoradiography, but it is less well studied in breast carcinoma. This report demonstrates the equivalence of TT and BrdU LI and explores the relationships between LI and other biologic measurements. Methods. The LI of 234 consecutive breast carcinomas were measured with TT as was a subsequent series of 450 cases with BrdU, both by incubation in vitro. Results. The mean BrdU LI was 6.4±0.3% in comparison with 6.9±0.4% in the prior TT series. LI was unaffected by storage for 24 hours at 4°CCbefore labeling with BrdU. The BrdU and TT LI both correlated (1) positively with tumor size, histologic type, nuclear size, the number of axillary metastases, the level of DNA ploidy, and the percent S‐phase by flow cytometry and (2) negatively with the age of the patient and the levels of estrogen receptor and progesterone receptor measured either by ligand binding or by immunohistochemistry. Conclusions. BrdU labeling in vitro was an advantageous method for measuring S‐phase fraction in breast carcinoma that produced results comparable to those from TT labeling. It should be equally effective for breast cancer kinetic classification and prognosis and is a suitable standard to evaluate newer methods for measuring cellular proliferation.

Measuring proliferation in breast cancer: practicalities and applications

“…The SPF can be calculated using a simple algorithm. Flow cytometry measurements of SPF have been shown to correlate with mitotic counts, histological grades and 3 HTdR LIs [13,14]. Clark and colleagues [15] have demonstrated that measurements of ploidy and SPF using flow cytometry can predict disease-free and overall survival.…”

“…This immunohistochemical method allows measurement of the SPF without the need for autoradiography or radioisotopes and has been shown to give similar results to 3 HTdR labelling [17]. Further work by Meyer and colleagues found BrdU labelling of breast cancer specimens to correlate with S-phase measured by 3 HTdR [18] and flow cytometry [14]. BrdU labelling has better resolution than 3 HTdR labelling, with less distortion of the nucleus or spill into the cytoplasm.…”

Rates of growth of human solid neoplasms: Part I

“…Gratzner [8] established that the thymidine analogue, 5-1 1 bromodeoxyuridine (BrdU) is also incorporated into DNA in the synthesis phase and that it could be detected immunohistochemically , providing an advantage over tritiated thymidine (TT), which only can be detected autoradiographically. Results with BrdU are equivalent to results with tritiated thymidine labeling [9]. Both TT and BrdU labeling indices correlated positively with tumor size, histologic type, nuclear size, the number of axillary metastases, the level of DNA ploidy, and the percent of S-phase by flow cytometry.…”

Endonuclease G promotes cell death of non-invasive human breast cancer cells

“…Increased breast cancer cell invasiveness is associated with progression and a poor prognosis in patients [1,2]. Commonly, invasive carcinomas have less apoptosis and are more resistant to chemotherapy [3][4][5].…”