I've got a study on the costs/benefits of chemo generally, although it
pre-dates Taxotere becoming mainstream, but the principles are the same.
 Benefit mostly depends on age and stage, with ER status as a minor
contributor.  Also there is a considerable variation in perception of
cost and benefit.  Basically if you are in the older age group and have
an early stage cancer, then there is little or no overall benefit.

Younger people have more life expectancy to lose, so their statistical
benefit is greater, and the loss of quality life during chemo is a
smaller part of it.

And with locally advanced cancers you get more "bang for your buck" with
chemo, if a treatment say halves the risk of recurrence, the higher the
initial risk the greater the benefit from it.

The balance is also tilted against chemo if there are any
"co-morbidities", i.e. pre-existing medical conditions, especially
cardio-vascular problems.

Tim Jackson