Table 3. Summary of studies investigating the effect of occult axillary lymph node metastases detected by serial sectioning and immunohistochemical staining for cytokeratin on disease-free and overall survival.

Study	No. of patients with negative lymph nodes	Patients with occult disease (%)	Multivariate analysis of disease-free survival (RR and 95% CI)	Multivariate analysis of overall survival (RR and 95% CI)
Tan et al. (2008)20	368	23	Node negative 1.0 Met. ≤0.2 mm 1.7 (1.0 to 2.9) Met. 0.3–2.0 mm 4.2 (2.1 to 8.5)a	Node negative 1.0 Met. ≤0.2 mm 1.4 (0.9 to 2.2) Met. 0.3–2.0 mm 2.5 (1.3 to 4.6)b
Cummings et al. (2002)18	208	25	Node Negative 1.0 Occult metastasis 2.17 (1.16 to 4.05)c	NS
Nasser et al. (1993)19	159	31	NS	NS

RR, relative risk; 95% CI, 95% confidence interval; NS, not significant.

^aP < 0.001.

^bP = 0.02.

^cP = 0.015.