“…Other explanations for the differences found were the woman's age at diagnosis (older women were less likely to undergo BCS) (Silliman et al, 1989;Cady and Stone, 1990;Farrow et al, 1992;Ganz, 1992;Satariano et al, 1992;Howe et al, 1995), geography (Cady and Stone, 1990;Ferguson et al, 1990;Farrow et al, 1992;Howe et al, 1995), and the availability of radiotherapy (Cady and Stone, 1990). Also, physician preference (Cady and Stone, 1990;Long, 1993), tumour size (Delouche et al, 1987;Cady and Stone, 1990;Margolese, 1995), the patient's own personal preferences (Cady and Stone, 1990), local medical customs and practices (Cady and Stone, 1990;Kiebert et al, 1991;Margolese, 1995), and co-morbidity (Satariano, 1992) all influence the choice of surgical procedure. Because we were able to use data on surgical procedures and length of stay from a national database, the treatment algorithms that we have developed incorporate the above-mentioned variations in practice patterns and surgical choices into the national average.…”