Tumour kinetics in breast cancer

In vivo bromodeoxyuridine was used to measure the 'bromo' labelling index (LI,%), the duration of the S-phase (Ts, hours) and the potential tumour doubling time (Tpot, days) in women with stages I-IV breast cancer. These were studied in relation to lymph node status, tumour size, histological grade, oestrogen receptor status (ER), ploidy and S-phase fraction (SPF). In our patients, a LI of 10%, a Tpot of 2 days or an SPF of 9-10.5% predicted aggressive breast cancer. The LI was significantly higher (5%) in ER-negative than in ER-positive (2%) tumours (P = 0.03). There was a trend towards increased DNA synthesis in cancers with an SPF over 10% (P = 0.08). ER-negative breast cancers over 2 cm in diameter had shorter median Tpots of 5.3 days (P = 0.02) and 8 days (P = 0.05) compared with smaller, ER-positive tumours. A trend towards faster growth rates was seen in lymph node-positive, high-SPF (> 10%) breast cancers. Tumour kinetics may have additional prognostic value in the selection of node-negative patients for adjuvant therapy.