Yes it is true that hydrogen peroxide is hard on cancer cells, however
in your nice's case she will need all the therapeutic approaches
possible, so it would not be adviseble substituting hydrogen peroxide
for a conventional therapy but it would be wise to use both, if that is
possible. It is also true that cancer grows less aggressively in an
alkaline environment, and there are many ways to achieve this, but
hydrogen peroxide should not be relied on exclusively to do the job.
Rest, relaxation, lots of laughter, a diet high is vegetable matter,
and regular intake of whey protein are some of the ways that help a
lot. Regular measurement of salivary pH with pH paper is a good way to
monitor the situation. Want to know more on breast cancer & treatment?
How about visiting these sites:
http://iotftraining.nci.nih.gov/shacter.html
http://www.breastcancercare.org.uk/Chat/Forums,
http://cancerforums.net/,
http://groups-beta.google.com/group/Cancer-treatments
http://breast-cancer-research.com/content/6/4/R264 etc.

No!

Firstly; hydrogen peroxide generates free radicals, which contribute to
causing cancer.  It is not a good idea to drink it.

Secondly it isn't an alkali, it is an oxidising agent.

Thirdly, if you made your body alkaline enough to kill off the cancer,
it would kill you too.  If you made it oxidant enough it might even
catch fire!

Fourthly, it would be very difficult to get it to the site of the
cancer.  Stage IV cancer is by definition systemic, at this stage tiny
cancers are spread all around the body.  Hydrogen peroxide or any simple
chemical such as an alkali given systemically would react with stomach
contents, blood, etc. (depending how it was administered) long before it
got to the cancer.

Mainstream cancer therapies work by killing cells, it is all about
discrimination.  They try to design the treatments to maximise the
killing of cancer cells while minimising the killing of normal cells,
but no-one has come up with a treatment that doesn't kill some normal
cells while simultaneously letting some cancer cells escape.  The
mainstream therapy is the best guess we have at maximising the chances
of survival for as long as possible.

Tim Jackson

Are you sure of your niece's stage?
Lymph node involvement does not automatically mean stage IV.
OTOH if she is stage IV her nodes are the least of her worries..
Forget the peroxide, its good for bleaching your clothes or hair and
thats it! Its also pointless to try and change the body's pH, if you do
it will be stressed until it regains the normal pH. As a simple test,
try hyperventilating for 1/2 an hour to make your body more 'alkaline'.
See how you feel? Once you've picked yourself up off the floor I hope
you'll realize the folly of extrapolating test results with cancer cells
in a petri dish to those in the body..
Ah, I see you alter ego 'Jeff Lopez' has the answer to all your
problems.  Quit wasting our time!

There is no evidence that hydrogen peroxide is effective against any
disease; there is evidence that it is harmful. It is a good disinfectant
for external use. search on www.quackwatch.com for "peroxide"

See the American Cancer Society's "Questionable methods of cancer
management: Hydrogen peroxide and other "hyperoxygenation" therapies"
http://caonline.amcancersoc.org/cgi/reprint/43/1/47

Hydrogen peroxide is a good fuel for rockets and submarines:
http://en.wikipedia.org/wiki/Hellmuth_Walter