Memorial Sloan Kettering Cancer Center (MSKCC) [14] has developed a software program to allow easy calculation of the risk for metastasis based on nine variables prior to undergoing a SLN biopsy, including age, tumor size, histologic tumor type, lymphovascular invasion, tumor location, multi-focality, histologic grade, and estrogen and progesterone receptor status. Here, PGR is linked to neoplasm.