I was unable to take aromatase inhibitors such as Letrozole,etc or tamoxifen.. The drugs caused serious side effects for me (I'm not good with many pharmaceuticals due to my allergies. So when I was unable to take them my oncologists referred me to a homeopathic doctor and clinic. The goal was to reduce my hormones or stabilize them to more normal levels. My breast cancer was highly estrogen positive. I had a long history with hormone problems that went pretty much undiagnosed, untreated and ignored for a lifetime (severe menstrual periods starting at age 8, difficulty and illness during pregnancy, and a long and difficult menopause). Via the naturopathic or homeopathic doctor I learned (via simple blood tests) that I had virtually no progesterone to counteract the estrogen in my system. I had higher testosterone, which can 'convert' to estrogen in the body post menopause, so I was an 'estrogen bomb' waiting to explode and it did, in the form of breast cancer ultimately.
There were additional tests done to tackle my allergies and some intestinal issues. Here is what I learned:

I needed to lose weight which can cause additional estrogen production in the body. I lost 30 pounds - weight I had put on during menopause.
I cut out as much processed food as possible, cut out chemicals in my diet and started using organic and GMO free foods and eating more 'natural' foods. I, like most people, eat too much sugar. I cut back on processed sugars.
I changed shampoos, lotions and other personal care items that included PABA, which is a preservative in those items that can convert to hormones (estrogen) in your body. I use a lot of lotion and I was slathering PABA on my body a few times a day. Anything I could do to cut down on estrogen was a plus. (I still miss some of those products however......some of the more 'natural' products aren't as pleasing to me as my old 'stand bys')
I found out I was Vitamin D deficient (not something that had ever been tested). I got a prescription strength Vitamin D supplement from my doctor and continue to take Vitamin D. Vitamin D deficiency has been shown to be one factor in breast (and other) cancers. Vitamin D is less of a 'supplement' and more of a hormone in your body and is essential to proper hormone function. The best way to get Vitamin D is in the sun but often we're all trying to avoid skin cancer - so I get 15 minutes of sun per day, without sunscreen, as well. Vitamin D also helps combat depression which is so common, especially for those who have cancer.
I'm not a yogurt fan but I found a yogurt drink I have each morning that I can tolerate and any digestive problems I had were gone (after a lifetime of them) in about 6 months. Keeping your gut healthy helps your whole body function better.
I added turmeric to my diet. Tumeric has anti-inflammatory qualities and has been shown in numerous studies to help prevent cancer.
The one thing I struggle with, which I'm sure contributes to cancer, is stress. I exercise and 'try' to meditate but being seriously Type A, I know the stress I'm under and don't control well also contributes to an unhealthy immune system.
I quit drinking all alcohol (all sugar and carbs) and I sheepishly admit I was a smoker. I am now a non-smoker (hardest thing I ever did).

These are just a few of the things I changed. Of course, I still got invasive cancer but I am just about to hit my 3 year anniversary from my mastectomies and so far so good. The combination of medical care and natural methods to improve my body's natural defenses is a work in progress. My medical doctors supported all these changes and I continue to research and try to improve the metabolism and structure of my body. I come from a time when Tang and Space Food Sticks were considered acceptable foods. I really didn't have a healthy outlook on food.

Because I don't take the aromatase inhibitors I finally asked my medical team why they didn't check women's hormones regularly to see what they had going on inside their bodies. Their answer was that all the breast cancer patients were taking the drugs so there was no need. Makes sense I guess.......but a baseline of where your hormones are that are fueling the cancer (if it's hormone positive) seemed like a simple test that would give women information they need. I have blood tests for my hormone levels every six months and I have NO ESTROGEN.....NO PROGESTERONE and little or no TESTOSTERONE. I'm not sure but I think that makes me non-human, but.........no estrogen and no progesterone means less fuel for the cancer to come back. I have experienced some of the same side effects due to the hormone loss that one would get with the aromatase inhibitors - hair loss, dry skin, etc. but none of the bone pain, depression, etc. from my low hormone levels.

I'm not as strict with myself as I should be. I still like a piece of chocolate cake now and then and I wouldn't classify myself as a health nut (not that disciplined) but I feel better, look better and I continue to try to get my old body in shape for the next decade, which I hope I'll have and that will be cancer free.