We read with interest the article ''A prospective study of breast size and premenopausal breast cancer incidence'' by Kusano et al. 1 Their main finding was that larger bra cup size at a young age was associated with a higher incidence of premenopausal breast cancer, though this association was limited to leaner women. The cup sizes were divided into the four categories ''A or smaller'', ''B'', ''C'', ''D or larger''. The authors did not take into account the rib cage circumference.
Most women who use brassieres are aware of the fact that cup size labeling is not standardized; different brands of brassieres differ in their labeling of cup size for the same breast volume. The actual cup volume of one brand's ''C'' may be equal to the cup volume of another brand's ''D''. Furthermore, cup size labeling takes rib cage circumference into account. An increase in rib cage circumference results in a decrease in cup size. Thus for two women with the same breast volume but different rib cage circumferences, the woman with the smaller rib cage would wear a larger cup size than the one with the larger rib cage.
We have measured the breast volumes of 355 women participating in an ongoing study regarding genetic and nongenetic factors that could be associated with breast cancer prognosis. Women scheduled for primary breast cancer treatment at the Lund University Hospital in Southern Sweden were invited to participate in the study, which was approved by the Lund University Ethics committee.
Written informed consents were collected during the preoperative visit at the Department of Surgery at the Lund University Hospital. During that visit, the research nurse collected a baseline questionnaire, which contained a question regarding brassiere size (e.g. 75A, 85C), and measured body weight, height, waist and hip circumferences, and breast volumes.
Three trained research nurses measured the volume of each breast with plastic cups used by plastic surgeons doing breast reductions and reconstructions. 2 The breast volume was measured with the patient in a sitting position with her arms hanging down. The volume measurements obtained from these cups have been used since 1994 together with a computerized program to prioritize patients on the waiting list for breast reductions at the Department of Plastic and Reconstructive Surgery of the University Hospital MAS, Malm€ o, Sweden. These cups come in the following 11 sizes : 200, 275, 350, 500, 650, 800, 950, 1150: 200, 275, 350, 500, 650, 800, 950, , 1325: 200, 275, 350, 500, 650, 800, 950, , 1500: 200, 275, 350, 500, 650, 800, 950, and 2000 mL. Weight mL. Weight was measured with the patient wearing light clothing.
The 355 participating women were between 25 and 99 years old. Fifty women reported using cup size ''A'', 128 used cup