9 Nov 2026
Do Hormones Cause Cancer? Five Questions That Take Apart Any Headline (Ep. 18, Pt. 1)
Do hormones cause cancer? The fear traces to one day in July 2002, when the Women's Health Initiative stopped one arm early: Premarin, a horse estrogen, with MPA, a copycat progestin. Neither arm of that trial gave estradiol or progesterone, and the same program's trial of Premarin alone ended up with fewer breast cancers and fewer breast cancer deaths than placebo.
Five questions that take apart any cancer headline. Where the fear came from. Estradiol and the breast, trial by trial. Why the breast signal follows the copycat progestin, not progesterone. Testosterone as the breast's brake. And the drivers you can actually act on: body fat, insulin, alcohol and light at night.
Part two, Wednesday: family history and BRCA, the breast cancer survivor, tamoxifen and the aromatase inhibitors, the prostate, every other cancer, and who benefits from keeping patients off hormones.
All research, opinions and clinical judgment are my own. This is education, not individualized medical advice.
CHAPTERS
00:00 Cold open: do hormones cause cancer?
04:28 Five questions for any cancer headline
11:59 Where the fear came from
24:57 Estradiol and the breast
33:10 Progesterone vs progestins
46:12 Testosterone, the brake
51:04 If not hormones, the real drivers
56:44 Close: part one
SOURCES
Adair & Herrmann 1946, Ann Surg, 123, 1023-35
Agrawal et al. 2024, J Sex Med, 21, 414-419
Anderson et al. 2012, Lancet Oncol, 13, 476-86
Brinton & Felix 2014, J Steroid Biochem Mol Biol, 142, 83-9
Chlebowski et al. 2010, JAMA, 304, 1684-92
Chlebowski et al. 2020, JAMA, 324, 369-380
Chlebowski et al. 2024, Breast Cancer Res Treat, 206, 177-184
Coelingh Bennink et al. 2017, Maturitas, 95, 11-23
Collaborative Group on Hormonal Factors in Breast Cancer 2019, Lancet, 394, 1159-1168
Cordina-Duverger et al. 2013, PLoS One, 8, e78016
Crandall et al. 2018, Menopause, 25, 11-20
de Lignières et al. 2002, Climacteric, 5, 332-40
Dimitrakakis et al. 2004, Menopause, 11, 531-5
Donovitz & Cotten 2021, Eur J Breast Health, 17, 150-156
Ellis et al. 2009, JAMA, 302, 774-80
Fels 1944, J Clin Endocrinol, 4, 121-125
Fournier et al. 2008, Breast Cancer Res Treat, 107, 103-11
Fournier et al. 2014, Breast Cancer Res Treat, 145, 535-43 (via Stute et al. 2018)
Fournier et al. 2014, Am J Epidemiol, 180, 508-17
Frandsen et al. 2024, Breast Cancer Res Treat, 208, 535-542
Glaser & Dimitrakakis 2013, Maturitas, 76, 342-9
Glaser et al. 2019, BMC Cancer, 19, 1271
Haddow et al. 1944, Br Med J, 2, 393-8
Hipolito Rodrigues & Gompel 2021, Women Health, 61, 3-14
Hodis & Mack 2008, Menopause Manag, 17, 27-32
Hodis & Sarrel 2018, Climacteric, 21, 521-528
Hofling et al. 2007, Menopause, 14, 183-90
Ingle et al. 1981, N Engl J Med, 304, 16-21
Janssen 2021, Int J Mol Sci, 22
Lalitkumar et al. 2023, Int J Mol Sci, 24
Lauby-Secretan et al. 2016, N Engl J Med, 375, 794-8
Li et al. 2017, Oncotarget, 8, 39896-39921
Lobo et al. 2018, Obstet Gynecol, 132, 161-170
Manson et al. 2013, JAMA, 310, 1353-68
Manson et al. 2017, JAMA, 318, 927-938
Meaidi et al. 2024, BMJ Med, 3, e000753
Mikkola et al. 2016, Menopause, 23, 1199-1203
Million Women Study Collaborators 2003, Lancet, 362, 419-27
Mirkin 2018, Climacteric, 21, 346-354
Montz et al. 2002, Am J Obstet Gynecol, 186, 651-7
Murkes et al. 2012, Gynecol Endocrinol, 28 Suppl 2, 12-5
Peethambaram et al. 1999, Breast Cancer Res Treat, 54, 117-22
Santen et al. 2013, Horm Cancer, 4, 195-207
Schernhammer & Hankinson 2005, J Natl Cancer Inst, 97, 1084-7
Schernhammer et al. 2008, J Natl Cancer Inst, 100, 898-905
Schierbeck et al. 2012, BMJ, 345, e6409
Smith-Warner et al. 1998, JAMA, 279, 535-40
Stute et al. 2018, Climacteric, 21, 111-122
Tamimi et al. 2006, Arch Intern Med, 166, 1483-9
U.S. Food and Drug Administration 2025, Drug Safety Communication
Vinogradova et al. 2020, BMJ, 371, m3873
Viscoli et al. 2001, N Engl J Med, 345, 1243-9
Writing Group for the Women's Health Initiative Investigators 2002, JAMA, 288, 321-33
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