It is when that activity doesn't switch off, we are looking at an increased cancer risk. Estrogen activity is the main cause of breast cancer, not anti-perspirants. Consequently, as one reaches menopause, those glands slow down even more - they are at their most active when we are in our most fertile years. The other type of gland that secretes perspiration is to maintain body temperature through evaporative cooling. Waste products that our body cannot use are primarily eliminated through our bowel and bladder, not perspiration.
Cells mutate in everyone, everyday.
It's a perfectly normal function that is normally controlled by our immune system. If a cancer pops up, anywhere for any reason, it's because our immune system hiccupped badly and missed it. People who have had a cancer diagnosis can use that knowledge to advantage by making sure that they adopt a lifestyle that will boost their immune system so that it will protect them. The reason that the underarm lymph nodes can become involved if a cancer does occur in breast tissue, is because of their physical location in the lymph drainage system. Our lymph system is analogous to our vascular system, but along the way are masses of protective lymph nodes, and those closest to an invading tumour are the first ones to either deal with the problem or fall victim to it.