Consistency of cyst type needs to be known

Editor—The reported observations of Paolo Bruzzi and colleagues relating breast cyst type to subsequent risk of breast cancer1 rekindles a well worn hypothesis. This, in its original form, was based on the following sequence of observations. Apocrine changes are reportedly more frequent in populations at the highest risk of breast cancer, and histological features for breast cancer may be more frequent in those with clinically palpable apocrine cysts. Thus patients with apocrine cysts (containing a high ratio of potassium to sodium concentration) will be more likely to develop breast cancer.2 For this to hold true it would require cyst type to be consistent for an individual. We understand, however, that the original proponents of this argument now find that their data no longer support this hypothesis (J M Dixon, personal communication).

In 1988 we published in support of an alternative hypothesis.3 While agreeing that breast cysts may arbitrarily be divided into two types, we argued that the sodium and potassium concentrations are unlikely to predict the future behaviour of the epithelium. Breast …