Hi,
I am, too, and 8/8 ER+ and on Letrozole. I finished my active treatment on 26th October 2016.
Having also completed a Moving Forward course, which is offered by Breastcancer Care in many areas, I hope my ramblings may be of help.
The key to much is a healthy balanced diet and to try and have a healthy BMI.
Dairy - many of us wonder whether we should stop it, as there has been concern voiced about hormones in milk. No, we should not avoid - quite the opposite. The intake of natural calcium is far better for our bodies than supplements. Although with the amount we need being on Letrozole we still need that supplement, especially as it also is combined with vitamin D. However we should switch to skimmed or semi skimmed milk and take it easy on full fat yogurts, cheese, etc.
This link is an excerpt of a european study re dairy, information which was given to us on our course, when asking about it.
ncbi.nlm.nih.gov/pubmed/23492346
Phytoestrogens - on this one the jury is out. And it has to be said that Letrozole does not minimise a possible effect, as Tamixifen might do. Letrazole stops an enzyme, which makes estrogen from our bodyfat and is hence different from the way Tamoxifen works.
Phytoestrogens mimic estrogen. The way to try and describe it - both have the same way of attaching to a cell - so if you imagine estrogen/phytoestrogen as puzzle piece with the bit sticking out. Our cells are the other puzzle piece with the hole, where the phytoestrogen/estrogen bit fits in. Estrogen would fit into this hole and would from there penetrate into the cell. Phytoestrogen also fits into this hole, but the scientists have, as yet, not found out whether it penetrates into the cell or not. If it would, that is not good news.
Research on BC and soya is out there, however it is based on an asian population with completely different diet. Soya having been a staple in their diet since time began, the asian popuation is likely to deal with soya differently to a european population. I have, as yet, not found any research on european population.
Phytoestrogens are in many foods, especially fruit and vegetables, which are very good for us.
However, I avoid foods which are high in phytoestrogens and also avoid any supplements such as Black Cohosh, Sage, Red Clover, etc. i.e. those supplements, which are supposed to help with menopausal symptoms.
I stay away from foods with over 1,000 …per 100g and take it easy with foods with over 500…per 100g

But, of course, it is always a very individual choice.
Parabens - there are many names for parabens - so it might be worth looking out for them on the back of shampoo, bubble bath, cosmetics, etc.
Methylparaben, is a member of the paraben family. Personal care ingredients that include: “ethyl,” “butyl,” “methyl,” and “propyl” are from the paraben family even if the word “paraben” isn’t in the name.
However parabens may be relevant for all of us, rather than being ER+. I personally will still by hair shampoo or soaps with paraben, as it is only used fleetingly and does not penetrate the skin. However , I do avoid them with all of my cosmetics.
Marks and Spencer does a good line in paraben free cosmetics and the Boots website is a good way to check whether a product you use/ or intend to buy contains them. Just search for your product, as if you would wish to purchase and then check the ingredients.
Phew - hope it helps
Hugs
Sue xx