Yes, some women can have orgasms solely from breast and nipple stimulation.
I would like to say all but there are a great many psychosocial factors that come into play. But the physical mechanism is there.
Breast and nipple stimulation has long been used to hasten childbirth as it causes uterine contractions due to the release of a hormone called oxytocin (also referred to as the "love hormone"). Recent studies have been done on the effect of breast massage on breast milk composition though I haven't been following those studies.
Lactation can be induced even in a woman who has never borne children though it is much easier to re-lactate a woman who has.
The physiology of it is quite simple .... the two hormones of interest are prolactin and oxytocin (mentioned above). All mammals M and F have trace levels of prolactin .. women, of course, have more. For the purposes of inducing lactation the main hormone of interest is prolactin.
Here is the physiology of it. With pregnancy a woman's level will rise x 100+. Non-pregnant women prolactin levels will rise ~10x - prolactin is actually an orgasm supressant and is what allows women to be "multi-orgasmic"; actually it is one big orgasm, it just ebbs and flows over a longer period of time, men tend to spend all their cookies in one go. Do a google search for prolactin and orgasm.
There are many many groups dedicated to the notion of induced lactation but imho they skirt the most important issue which is the direct relationship between arousal, orgasm, and hormone levels that are vital to making it work. Self-honesty is the vital key as really, outside of the psychosexual aspect of induced lactation (except in the case of an adoptive mother wanting to breast feed her infant) there is no real biological reason for a woman without a child to have breast milk .. though some do as just a hormonal variation. The euphamistic notion of "wanting the closeness of an adult breastfeeding relationship" misses the point and is a barrier to success imho. "I really love my breasts and want to enjoy them to the fullest" is a more helpful attitude imho. .... and why not? *smiles
You'll find an ad in the ad section way back there where I was asking for female volunteer research subjects for an ongoing breast orgasm study which is still ongoing.
I was an RN for 15 years and have had my fill of clinical medicine so my research is more along the lines of the psychosocial, historical, and pop-culture factors. If I may it has always been a real eye-opener for the participants as they are all, without exception, breastcentric to a large extent and most of them have felt "wierd" as it were for being so. All have found my study to be liberating in that they see they are not "wierd" or alone in this aspect of their sexuality and that it is very ok to revel in this wonderful part of themselves. My study is still open and new subjects are always welcome. Please leave me a PM if you are interested.
Over the years I have developed this technique I call a deep milkduct massage that I teach to all participants. I have worked (if you can call it that) hard over the years to develop this technique with the help of a lot of wonderful women and I am reluctant to talk much about it beyond this brief mention. Suffice it to say that it is very very erotic and is designed to elicit the maximum amout of pleasure from a woman's breasts and a breast orgasm is the desired outcome. It is not painful but a woman should know that her nipples will be very sensitive (in the good sense) for a day or so afterwards .. women probably already know what I am talking about.
Induced lactation programs are also something I offer
For women who are interested in becoming a volunteer in my research project please understand that it is your breasts that are the subject of interest in my research and that by nature it will be eroticly arousing.
Opinions will differ, I said yes earlier in this thread, some have respectfully disagreed. My evidence is anecdotal as is everyone elses.
As part of my ongoing research, I am looking for research subjects - women who are very breast oriented who can help me answer that question in a documented way .. If nothing else it could be a lot of fun :)
I'm West Coast (Los Angeles, Seattle, and Vancouver BC) Please PM me if interested.