DOSIMETRIC BREAST SIZE - A NEW AND USEFUL PARAMETER FOR THE PREDICTION OF LOCAL RECURRENCE AFTER BREAST CONSERVATIVE TREATMENT

To evaluate the risk of local recurrence following breast-concerving t herapy for breast cancer, we measured the distance between each entry point of the irradiation on the surface of the breast in line with the axis of the external and internal tangential fields (dosimetric breas t size). 652 breast cancer patients were retrospectively analysed, wit h a median age of 51 years and a median follow-up of 99 months (range 84-192). There were 50 local recurrences, 44 isolated and 6 associated with nodal recurrence or metastases. The global rates of local recurr ence at 5 and 10 years were 5.3% and 9%, respectively (Kaplan-Meier an alysis). Following a Cox's multivariate analysis, the only significant and independent parameters related to local recurrence were quality o f excision, age at diagnosis and dosimetric breast size. For a small d osimetric breast size (less than or equal to 10 cm), the rate of local recurrence was 14.1 compared with 11.8 for medium dosimetric breast s ize (> 10 cm-less than or equal to 12 cm) and 5.2 for large dosimetric breast size (> 12 cm). If the analysis was restricted to only those w ith complete excision, then the relative risk for a patient with a sma ll dosimetric breast size was three times that for a large breast size . (C) 1997 Elsevier Science Ltd.