Before I realized that this question was already answered, I got excited and did some research myself. Tiantian gave a great start, so I tried to remove duplicate references from my list (I might have missed a few). I also tried to include a few conflicting findings to let you come to your own conclusions. As tiantian mentioned, many of these works are newspaper or magazine articles as opposed to studies, but if you look at the works cited or browse the articles for mentions of the studies you will be able to search with more targeted terms. Good luck- this is a really interesting subject!
PS- forgive the spotty citation formatting.
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Ault, A; First COX-2 inhibitor clears initial FDA hurdle
The Lancet- Vol. 352, Issue 9144, 12 December 1998, Page 1912
Burros, Marian; A Hormone For Cows
New York Times. (Late Edition (East Coast)). New York, N.Y.: Nov 9, 2005. pg. F.10
Burton, J.L. and B.W. McBride; Recombinant bovine somatotropin (rbST): Is
there a limit for biotechnology in applied animal agriculture?
Journal of Agricultural Ethics 2 (1989): 129-159.
Burton, J.L., B.W. McBride, E. Block, D.R. Glimm, and J.J. Kennelly; A review of
bovine growth hormone
Canadian Journal of Animal Science 74 (1994): 167-201
Colditz, Graham A; Hankinson, Susan E; Holmes, Michelle D; et al; Intake of Dairy Products, Calcium, and Vitamin D and Risk of Breast Cancer
Journal of the National Cancer Institute, Vol. 94, No. 17, 1301-1310, September 4, 2002
Etherton, Terry D; The Efficacy, Safety and Benefits of Bovine Somatotropin and Porcine Somatotropin
Prepared for the American Council on Science and Health- ACSH Publications- 1994 - acsh.org
Furth, Pauline; Bovine Growth Hormone: The Chemical Soup in Your Cup
Against the Current. Detroit: May/Jun 1995.Vol.X, Iss. 2; pg. 7
Gillette, Becky E; Doin' a Body Good? Studies Link rBGH-Produced Milk and Increased Cancer Risk
the Environmental Magazine. Norwalk: Sep/Oct 1998.Vol.9, Iss. 5; pg. 42
Kingsnorth, Paul; Bovine growth hormones. (by Monsanto Co)(includes related articles on bovine growth hormone and cancer).
The Ecologist v28.n5 (Sept-Oct 1998): pp266(4).
Morris, K; Bovine somatotropin—who's crying over spilt milk?
The Lancet - Vol. 353, Issue 9149, 23 January 1999, Page 306
Turner, R. Steven. Of milk and mandarins: rBST, mandated science and the Canadian regulatory style
Journal of Canadian Studies 36.3 (Fall 2001): 107(24).