I’ve treated a lot of breast cancer patients and usually something can be done to mitigate the side effects of endocrine therapy. There are exceptions of course but there is no data that supports lifestyle change as a substitute for endocrine therapy for ER positive breast cancer.

It may be that the overall risk of metastatic disease is low because of small tumor size and negative nodes. But for someone that really needs the treatment, it’s is mistake to not try to make adjustments.

ER positive breast cancer has a metastatic risk window extending over 20–30 years even with endocrine therapy based on studies from Canada, the UK and Denmark.

For a stage 3 patient taking either tamoxifen or an aromatase inhibitor, the metastatic risk could be 20% at 5 years. That is why in the US, ovarian suppression is added in premenopausal patients, and also 2 years of Verzenio (also to postmenopausal patients), for higher risk patients.

Endocrine therapy will generally reduce metastatic risk by 50–60%. Even 1–2 years, is better than zero years of use.

Very regular exercise can reduce metastatic risk by 55%. But doing both is better than just doing one thing because treating metastatic breast cancer with indefinite dual endocrine therapy by adding a CDK4/6 inhibitor is usually harder both physically and emotionally than taking preventative endocrine therapy in remission.

For hot flashes from treatment, low dose antidepressants such as Effexor and trazodone can reduce symptoms in half of patients. Acupuncture also helps half of patients, as does biofeedback and relaxation training. In May 2023, the FDA approved Veozah, an NK3 inhibitor, that is very effective in releasing hot flashes, generally with only minor GI side effects.

Atrophic vaginitis with painful intercourse will respond to low dose vaginal estrogen and is part of the ACOG guidelines.

Joint and muscle discomfort from aromatase inhibitors can response with a treatment holiday of 4–8 weeks and sometimes changing medications from anastrozole, to letrozole to exemestane. Very regular exercise definitely reduces symptoms. Occupational therapy with specific finger exercises can reduce hand symptoms. Low dose Cymbalta has been show to help as well.

For patients experiencing depression, sometimes a combination of estrogen replacement therapy with concurrent tamoxifen can help postmenopausal patients.

There is zero data that a plant based diet without weight reduction will reduce metastatic risk. Keep in mind that optimal weight management and very regular exercise will reduce delayed metastatic disease as the metabolic and immune function improvements take years to come into play. So these interventions are important but no substitute for addressing shorter term risk by taking standard endocrine therapy.

Whether or not omitting that treatment is appropriate depends on your breast cancer stage, your age, your long term goals. If you are a 38 year old mother of 2 kids, that is different than being a 78 year old widow. If you are the former, you have a responsibility to be there to raise your kids. If your are the latter, then do whatever you want.

Wishful thinking is not a cancer treatment. Please choose wisely.

This answer is not a substitute for professional medical advice. This answer is for general informational purposes only and is not a substitute for professional medical advice. I am an oncologist but I am not your oncologist.