Cell proliferation of the primary tumor predicts ipsilateral axillary node disease in elderly breast cancer patients

The present study investigated whether tumor markers such as cell proliferation and steroid receptor status, which have been shown to have relevance for important endpoints (relapse-free and overall survival), can also predict axillary disease in elderly patients with breast cancer. We evaluated 351 consecutive elderly women with breast cancer ≥70 years of age with estrogen receptor (ER)‑positive tumors with no palpable axillary nodes, for whom information on cell proliferation determined by the 3H-thymidine labeling index (TLI) and progesterone receptor (PgR) was available. Patients underwent quadrantectomy (70.1%) or quadrantectomy plus radiotherapy (29.9%) without axillary node dissection, followed by adjuvant tamoxifen for at least 2 years. Univariable (cumulative incidence curves) and multivariable analyses (Fine and Gray models) were carried out. After a median follow-up of 16 years, ipsilateral axillary relapse was not related to PgR status but was strongly associated with tumor cell proliferation in both small (pT1) and large (pT2-4b) tumors. Axillary relapse cumulative incidence increased from 1% in patients with low-TLI (≤3%), PgR-positive and pT1 tumors to a maximum of 20% in patients with high-TLI, PgR-negative and pT2-4b tumors. Tumor cell proliferation, determined by TLI at primary surgery, is an important predictor of axillary relapse in elderly ER-positive breast cancer patients and could help to identify patients who should undergo axillary surgery.