Breast size and prognosis in early breast cancer.

The influence of breast size on the prognosis of 196 patients with early breast cancer diagnosed in the period 1984-1985 was studied. Breast size was based on the volume from mammography. This method was validated against the volume of the mastectomy specimen determined by water displacement in 18 patients and found to be accurate (r = 0.93, P < 0.01). The median breast volume was 833.5 cm3 (interquartile range 522.8-1153.3 cm3). Breast size was significantly associated independently with age (Spearman's rank r = 0.24. P = 0.001), menstrual status (z = -4.81, P < 0.001), body weight (Spearman's rank r = 0.61, P < 0.001), T stage (z = -1.91, P = 0.05) but not N stage (z = -1.64, P = 0.10) or hormone receptor status (z = -0.80, P = 0.42). In an analysis of breast size and other known prognostic factors, based upon Cox's proportional hazards regression, N stage was the only significant factor for both breast cancer survival and disease-free survival. Even though women with larger tumours at presentation had larger breasts, breast size was not a significant prognostic factor in early breast cancer.