Well, what an interesting topic to jump into. I had breast cancer when I was 48, and the chemo started what was called "chemical induced menopause." I had my first chemo treatment on Nov 2, the first day of the last period of my life. Prior to that I was on mood-modifiers, not for a mental illness mood disorder, but for hormone related mood swings, what is now called PMDD: pre-menstrual dysphoric disorder. I too planned vacations around the menstrual cycle. So, one of the best unexpected experiences of cancer was to go through menopause within chemo treatment. I had hot flashes, night sweats too for six months to a year, but no telling if it was hormone or chemo/radiation related. In a younger woman, studies show that chemo might interfere with menstrual cycles but then her normal cycles will return. Good to know for a younger woman who wants to have children despite cancer/chemo.