Hi all.  I'm also on the same breast cancer listserv as our Kathy Rosenthal.
I'm a mostly lurking "newbie" here also.
Saw this thread re lignans in flax seed/flax oil.   I have been delving through
research for many months on the topic of cancer and phytoestrogens (lignans
metabolize into phytoestrogens in our gut).  It seems no one knows for absolute
certain and more research is yet needed.

From what I've gathered, phytoestrogens are a good thing to include in diets if
you are premenopausal, and free of cancer.  If you are postmenopausal and have
had or have cancer, they MAY POSSIBLY help SOME cancers grow faster.  I really
don't know how this issue applies to men and prostate cancer, but I think it is
similar.
But controversy abounds.  Lots of research with support to both sides of the
argument.    I personally use flax seeds but avoid all soy products.

Cancers have several attributes that are categorized.  For breast cancers, one
of them is whether or not the cells of the cancer tumor have receptors on them
that are able to have estrogen attach to them (and feed tumor growth).   These
are called ER+ tumors, which means estrogen positive.  Some breast cancer tumors
are estrogen negative.   Current research seems to strongly indicate that anyone
who has or had an ER+ breast cancer tumor should realize there are POSSIBLE
tumor growth risks associated with phytoestrogens.  Flax and Soy are the richest
sources, but all or most  plants from A to Z contain some.   As to colon cancer,
I don't know much other than to know that the fiber that is in flax seeds (not
the oil) is protective because colon cancer is thought to possibly have some
genesis in low fiber intake.

But because flax seeds are so rich in Omega-3 essential fatty acids which our
bodies cannot make for themselves, they are a very attractive food for those who
are known to be healthy.  The research I've read indicates they do play a strong
role in prevention, and the research that doesn't think they promote tumor
growth think they also play a strong role in preventing tumor growth.

Seeds versus oil is an ongoing debate.  I personally have become convinced that
seeds are much better simply because anything closer to its "natural" state has
won that "what is best" contest so many times in other arguments.  However, I
know that a company called "Barleans" makes as good of a high quality product as
can probably be purchased.  They make a couple of kinds, and their most
expensive says on the label it is "hi lignan"....which may mean one of a couple
of things, and I haven't been able to find out which.  One meaning might just be
that because flax seeds are hi-lignan, so then is the oil (like hot peppers,
their pressed juice  could be called hi capsicain, yet really not be a
quantitative description) As Barleans cold presses the seeds without filtering,
lignans in the seeds probably move into the oil during pressing.  How much? all
of it?  probably not?  just using common sense here.  But the second thing is I
read at some web site that some mfg. do ADD lignans.  Barleans doesn't say if
they do or do not add lignans.  Then, if it were found they added them, one
would question where the additions came from
(freshness, temp, light, etc).  I've personally decided that flax oil is a
product "fad" that really might have a use at a fancy-celebration type meal
where you'd rather have the oil to put on the hot asparagus rather than having
ground seed meal on them.  But for everyday use, I really am not sure why anyone
would even want the oil unless its a total convenience thing.  But I used the
oil until recently, when I figured all this out!

And I've read at several sites saying  the ground flax seed meal is so wonderful
for purchasing.   I fail to see anything wonderful about that.  Fresh is fresh,
eh?  I buy whole seed and keep it in my freezer.  I grind what I'm going to use
right when I'm going to use it.  Heat destroys some of the nutrients, so the
idea of using it in baking or cooking is probably not the very best of ideas.  I
personally find I love the flavor enhancement by sprinkling them over steamed
veggies or greens, or tossing them into grilled onions.  It tastes like nutty
butter to me.

I can also rely on my taste buds to let me know about freshness.  Also, the
seeds, if kept in the freezer in good quality containers where air is removed
again after each time you get in it (and assuming the seeds were fresh when you
bought them), will easily keep 6 months.

Katy