The trouble with identifying risk factors for any disease is that, if
you don't have detailed information about the precise mechanisms, you
have to rely on statistical information. I won't use breast cancer as an
example -- to close to think objectively about. The value of a
statistical study depends upon the number of people involved and the
qualify of the study. Unfortunately, the experience of one person has to
have no statistical value: "I smoke 40 cigarettes a day and here I am at
90". Even "I phoned all the people I know and came up with these
figures" is far less than perfect; maybe you were all from the same area
(with high background radiation); maybe people who have telephones have
a healthier lifestyle?

I go into this not as a theoretical discussion, but because we all have
to judge future risks on present information, and we need to know how to
evaluate information.

Information published in the press and non-specialist publications, if
based on good studies, can be more meaningful, but can also be
dangerously misleading.

Information in medical journals, seen and criticised by other
researchers, is the best we have; but by no means perfect. Published
researchers are human; they make mistakes, have biased opinions which
affect their judgment, in rare cases just make up results and cheat,
have commercial sponsors keen to publish favourable results and suppress
unfavourable ones, and can produce results which are correct but
misleading. For example, some recent work (I don't remember the study
area, possibly bc) came up with results about a "one-in-9-chance" of
getting ill. But this turned out to be over a 10-year period, and was
misleading even for physicians.

As an example, look at how long it took to uncover the huge, glaringly
obvious, correlation between smoking, and heart disease and lung cancer.
Tobacco has been around for centuries; reports of these consequences
were fist published in 1950. I remember great arguments by smokers
rubbishing the idea that smoking caused cancer as late as the late
1970s. In earlier years parents sometimes recommended that their young
adult children should take up smoking (e.g., author Roald Dahl in his
autobiography "Going solo" about events of the 1930s).

Basically, the only way to get good information is to read what's been
done, and see what comes out. Earlier studies suggested that HRT was a
significant risk fact; the latest one reported in this thread says it's
much less important than thought.  Other researchers will be queuing up
to either knock down or confirm the newer results. The story is not
finished.

I don't have a medical background, buy am OK at statistics.

I hope this helps someone. To add to the anecdotal information: my wife
didn't take HRT but developed IBC/IV; this has no statistical value.

Best wishes,