RESUMEN
National Comprehensive Cancer Network guidelines suggest a selective workup of early-stage breast cancer with complete blood count (CBC) and liver function tests (LFTs) and no longer recommend chest X-ray (CXR) to screen for occult metastasis. We evaluated the utility of routine preoperative screening tests in patients with clinically node-negative (cN0) breast cancer. We identified 1611 patients with cN0 breast cancer treated at our institution between October 1998 and December 2015; 94.4 per cent of the patients underwent at least one preoperative screening test: 90.8 per cent CBC, 89.4 per cent LFTs, and 63.6 per cent CXR. Thirty-six per cent of CBCs, 13.1 per cent of LFTs, and 6.7 per cent of CXRs were abnormal. Abnormalities led to 17 CT scans, and one found an occult metastasis. Eleven patients (0.7%) were diagnosed with metastatic disease postoperatively, but only half had abnormal preoperative screening tests. Positive predictive values of preoperative CBC, LFTs, and CXR for occult metastasis are 1.3 per cent, 1.1 per cent, and 1.5 per cent, respectively. Preoperative screening in cN0 breast cancer is of low yield. Even when abnormalities are found, metastasis is present in less than 1 per cent of patients, and a normal study does not rule out metastasis. Routine preoperative determination is not warranted, and staging studies should be limited to patients with signs or symptoms.