I agree. This is unfortunately, an area with a lack of data, though in my experience, most women who are treated for breast cancer during pregnancy are still in the middle of therapy (systemic or local) after delivery, so we typically recommend against breastfeeding to avoid delays, particularly wit...

I do not know of any data that addresses this question. If the mother strongly wishes to breastfeed, I would probably feel comfortable delaying the start of endocrine therapy for 3 months or so, which is the period of time that provides the greatest benefit to mother and child. If she has had a lump...