Studying the effect of dietary fat on prostate cancer development, UCLA researchers found that animals on a low-fat diet (12% calories from fat) were significantly less likely to develop invasive prostate cancer compared to animals on a high-fat diet (42% calories from fat).  
Kobayashi, N., R.J. Barnard, J. Said, J. Hong-Gonzales, D.M. Corman, M. Ku, N.B. Doan, D. Elashoff, P. Cohen, W.J. Aronson. Effect of low fat diet on development of prostate cancer and the Akt pathway. Cancer Res. 68:3066-3073,2008

The Pritikin Program was found to reduce prostate cancer cell growth by as much as 45%, which should drastically reduce the risk for clinical cancer.  Reductions in serum insulin, free testosterone, estradiol, and IGF-1 along with a rise in SHBG and IGFBP-1 appear important.  The decrease in IGF-1 appears to be the most significant change because IGF-1 normally prevents cells from going into apoptosis (cell death).
Barnard, R.J. Cancer of the Prostate, Benign Prostatic Hypertrophy, Diet and Exercise Intervention. www.Vitasearch.com. May, 2008

Effect of diet and exercise intervention on the growth of prostate epithelial cells.
Prostate Cancer and Prostatic Diseases, advance online publication, 19 February 2008; doi:10.1038/pcan.2008.6

The Pritikin Program Was Shown To Reduce Risk of Prostate Cancer
Barnard, R.J. P.S. Leung, W.J. Aronson, P. Cohen, L.A. Golding. A mechanism to explain how regular exercise might reduce the risk for clinical prostate cancer. The European Journal of Cancer Prevention 16:415-421, 2007

The Pritikin Program Was Found To Be Superior Over Supplementation For Prevention of Prostate Cancer: Soy Supplements Did Not Decrease IGF-I Levels
Dewell, A., G. Weidner, M.D. Sumner, R.J. Barnard, R.O. Marlin, J.J. Daubenmier, P.R. Carroll, D. Ornish. Evaluation of dietary protein and soy isoflavones in relation to serum IGF-I and IGF binding proteins in the Prostate Cancer Lifestyle Trial. Nutrition and Cancer 58:35-42,2007

Scientists Affiliated With the Nathan Pritikin Research Foundation Studied the Effects of Omega-6/Omega-3 Ratios On Prostate Cancer Cells
Kobayaski, N., R.J. Barnard, S.M. Henning, D. Elashoff, S.T. Reedy, P. Leung, J. Hong-Gonzalez, S.J. Freedland, J. Said, D. Gui, N.P. Seeram, L.M. Popoviciu, D. Bagga, D. Heber, J.A. Glaspy, W.J. Aronson. Effect of Altering Dietary Omega-6: Omega-3 Fatty Acid Ratios on Prostate Cancer Membrane Composition, Cyclooxygenase-2 and Prostaglandin E-2. Clin Cancer Res. 12:4662-4670,2006

Scientists Affiliated With the Nathan Pritikin Research Foundation Investigated the Potential Health Benefits of Pomegranate Juice Consumption
Pantuk, A.J., J.T. Leppert, W. Aronson, J. Hong, R.J. Barnard, N. Seeram, H. Wang, R. Elashoff, D. Heber, L. Ignarro, A. Belldegrun. Phase II study of pomegranate juice for men with rising PSA following surgery or radiation for prostate cancer. Clin. Cancer Res. 12:4018-4026,2006

The Pritikin Program Was Shown To Retard the Growth of Breast Cancer Cells
Barnard, R.J., J.H. Gonzalez, M. Liva, T.H. Ngo. Effect of a low-fat, high-fiber diet and exercise program on breast cancer risk factors in vivo and tumor cell growth and apoptosis in vitro. Nutrition and Cancer 55:28-34,2006

Lifestyle Changes Halt Progression of Early-Stage Prostate Cancer
Ornish D, Carroll PR, Fair WR, Pettengill EB, Marlin R, Raisin CJ, Dunn-Emke S, Crutchfield L, Barnard RJ, McCormac P, McNight DJ, Fein JD, Dnstrian AM, Weinstein J, Ngo T, Weidner G. Intensive lifestyle changes may affect the progression of prostate cancer. J Urol 174:1065-1070, 2005.

The Pritikin Program Was Found To Reduce Cancer Cell Growth
Barnard, R.J. and W.J. Aronson. Preclinical models relevant to diet, exercise, and cancer. In: Recent Results in Cancer Research (Controversies in Tumor Prevention and Genetics III). H-J. Senn and R. Morant, eds. Springer 2005, 166:47-62.

The Pritikin Program Was Found To Control Insulin Resistance and Reduce IGF-1, Which Might Reduce the Risk For Many Cancers
Barnard, R.J. and Aronson, W.J. Diet, Exercise and Prostate Cancer. In: Prostate Cancer, J.N. Lucas ed. Nova Science, Hauppauge, N.Y. Chapt. I, 2004.
Barnard, R.J. Prevention of cancer through lifestyle changes. eCAM Jol 1:233-239, 2004.

Daily Exercise Was Found To Reduce Prostate Cancer Cell Growth
Leung, P-S.,W.J. Aronson,T.H. Ngo, L.A. Golding and R.J. Barnard. Exercise alters the IGF axis in vivo and increases p53 protein in prostate tumor cells in vitro. J. Appl. Physiol. 96:450-454, 2004.

Low-Fat Diet Was Found To Significantly Prolong Life in Animals With Prostate Cancer
Ngo, T.H., R.J. Barnard, T. Anton, C. Tran, D. Elashoff, D. Heber, S.J. Frieedland and W.J. Aronson. Effect of isocaloric low-fat diet on prostate cancer xenograft progression to androgen independence. Cancer Res. 64:1252-1254, 2004.

The Pritikin Program Was Found To Reduce Cancer Cell Growth Via Decreases In IGF-1 and Increases In IGFBP-1
Ngo, T.H., R.J. Barnard, P. Cohen and W.J. Aronson. IGF-1 and Insulin-like growth factor binding protein-1 (IGFBP-1) modulate prostate cancer cell growth and apoptosis: Possible mediators for the effects of diet and exercise on cancer cell survival. Endocrinology 144:2319-2324,2003

The Pritikin Program Was Found To Reduce Prostate Cancer Cell Growth By As Much As 45%
Barnard, R.J., T.H. Ngo, W.J. Aronson and L.A. Golding. A low-fat diet and/or strenuous exercise alters the IGF axis in vivo and reduces prostate tumor cell growth in vitro. Prostate 56:201-206,2003

Low-Fat Diet Was Found To Be Linked With Slower Prostate Tumor Growth
Ngo, T.H., R.J. Barnard, P. Cohen, S. Freedland, C. Tran, F. deGregorio, Y.I. Elshimal, D. Heber and W.J. Aronson. Effect of isocaloric low-fat diet on human LAPC-4 prostate xenografts and the IGF axis in SCID mice. Clin. Cancer Res 9:2734,2003

The Pritikin Program May Reduce the Risk For Prostate and Other Hormone-Related Cancers By Reducing the Insulin-Resistance Syndrome
Barnard, R.J., W.J. Aronson, C.N. Tymchuk and T.H. Ngo. Prostate cancer: Another aspect of the insulin resistance syndrome. Obesity Rev 3:303-308,2002

The Pritikin Program Was Found To Retard the Growth of Prostate Cancer Cells and Induce Cancer Cell Death (Apoptosis)
Ngo, T.H., R.J. Barnard, C.N. Tymchuk, P. Cohen. And W.J. Aronson. Effect of diet and exercise on serum insulin, IGF-1, and IGFBP-1 levels and growth of LNCaP cells in Vitro. Cancer Causes & Control 13:929-935,2002

The Pritikin Program Was Found To Reduce Serum Hormones That Play A Role In Prostate Cancer Growth
Tymchuk, C.N., R.J. Barnard , T.H. Ngo and W.J. Aronson. The role of testosterone, estradiol, and insulin in diet and exercise-induced reductions in prostate cancer cell growth. Nutrition and Cancer 42 (1): 112-116, 2002

The Pritikin Program Resulted In Serum Changes That Significantly Reduced the Growth Of Prostate Cancer Cells In Vitro.
Tymchuk, C.N., R.J. Barnard, D. Heber and W.J. Aronson. Evidence for an inhibitory effect of diet and exercise on prostate cancer cell growth. J. Urol . 166:1185-1189,2001

The Pritikin Program Increased Levels Of Sex Hormone-Binding Globulin and Reduced Levels of Insulin, Which Should Reduce the Risk for Breast Cancer In Postmenopausal Women
Tymchuk, C.N., S.B. Tessler and R.J. Barnard. Changes in sex hormone-binding globulin, insulin and serum lipids in postmenopausal women on a low-fat, high-fiber diet combined with exercise. Nutrition and Cancer 38:158-162,2000

The Pritikin Program May Reduce the Risk For Prostate Cancer By Altering Serum Hormones That Affect Prostate Cancer Growth
Tymchuk, C.N., S.B. Tessler, W.J. Aronson and R.J. Barnard, Effects of diet and exercise on insulin, sex hormone-binding globulin and prostate-specific antigen. Nutrition and Cancer, 31:127-131,1998

In Healthy Premenopausal Women, the Pritikin Eating Plan Reduced Estradiol and Estrone Levels Without Affecting Ovulation, Thereby Providing a Rationale For The Prevention Of Breast Cancer
Bagga, D., J.M. Ashley, S.P. Geffrey, H-J. Wang, R.J. Barnard, S. Korenman and D. Heber, Effects of a very low fat, high fiber diet on serum hormones and menstrual function: Implications for breast cancer prevention. Cancer, 76:2491-2496,1995

A Low-Fat, High-Fiber Diet Was Found To Modulate Lipids In Ways That May Be Cancer-Protective
Bagga, D., J.M. Ashley, S. Geffrey, Hei-Jung, R.J. Barnard, R. Elashoff and D. Heber, Modulation of serum and breast duct fluid lipids by a very low-fat, high-fiber diet in premenopausal women. JNCI, 86:1419-1421,1994

The Pritikin Program Was Found To Lower Estradiol Levels On Average 40%. Estradiol Is a Hormone That In Excess Stimulates the Growth of Breast Tumors.
Heber, D., J.A. Ashley, D.A. Leaf, R.J. Barnard. Reduction in serum estradiol in postmenopausal women given free access to a low-fat, high-carbohydrate diet. Nutrition, 7:137-40,1991.

The Pritikin Eating Plan Was Found To Decrease Concentrations of Fecal Bile Acids and Neutral Sterols
Reddy, B. S., A. Engle, B. Simi, L.T. O'Brien, R.J. Barnard, N. Pritikin and E. L. Wynder. Effect of low-fat, high carbohydrate, high-fiber diet on fecal bile acids and neutral sterols. Preventive Med ,17:432-439, 1988.