Hormone Therapy After Risk-Reducing Surgery in BRCA Carriers: Why are we still arguing about this?

There are topics in medicine where the data evolve slowly and cautiously. And then there are topics where the data have been sitting, quite patiently, waiting for us to catch up.

Hormone replacement therapy (HRT) after risk-reducing oophorectomy in BRCA mutation carriers falls squarely into the latter category.

The evidence is not new. It is not particularly controversial. And yet, the clinical hesitation persists, and patients are being negatively impacted.

The question that keeps circling: A woman with a BRCA1 or BRCA2 mutation undergoes risk-reducing bilateral salpingo-oophorectomy (RRSO). Ovarian cancer risk drops substantially. That part is clear. What about breast cancer? Does HRT increase her risk of breast cancer?

Regev-Sadeh et al., 2026

A retrospective cohort of 919 BRCA carriers, followed for nearly nine years.

• Estrogen-only HRT was not associated with increased breast cancer risk

• In BRCA1 carriers, it was associated with a reduction in risk (HR 0.87 per year of use)

• Combined estrogen-progestin therapy showed a neutral effect (HR 1.06)

A detail worth pausing on: prior use of progestin-only contraception (LNG-IUD) correlated with increased breast cancer risk in BRCA1 carriers.

Marchetti et al., 2018

A meta-analysis, modest in size but directionally consistent.

• No increase in breast cancer risk with HRT (HR 0.98)

• A trend favouring estrogen-only over combined therapy

Not definitive on its own, but it aligns neatly with what followed.

Kotsopoulos et al., 2018

Prospective data, which tends to carry more weight.

• Estrogen-only HRT: no increased risk

• Breast cancer incidence:

  • 12% with estrogen-only

  • 22% with combined therapy

The difference widened in women who underwent surgery before age 45, which is precisely the group most affected by abrupt estrogen deprivation.

Gordhandas et al., 2019

A systematic review that broadens the lens.

• HRT does not negate the protective effect of oophorectomy

• It does, however, mitigate the predictable consequences of premature menopause:

  • Cardiovascular decline

  • Bone loss

  • Cognitive changes

  • A general erosion in the quality of life

None of this is surprising. Estrogen has physiological roles. Removing it has consequences.

The Pattern Is Not Subtle

Across study designs, populations, and years of follow-up, the conclusion remains the same. HRT after risk-reducing oophorectomy in BRCA carriers does not increase breast cancer risk.

• Estrogen-only therapy appears to be the most favourable

• Combined therapy is, at worst, neutral

One might expect this to settle the matter… and yet … fewer than half of eligible women are offered HRT after these procedures.

This is where things become less about evidence and more about inertia.

The concern, historically, has been that hormones, particularly estrogen, fuel breast cancer. In some contexts, that concern is valid. In this context, it is not supported by the data we have. But clinical habits are slow to shift, especially when fear has had a long runway.

Sadly, there is a cost of hesitation. When ovaries are removed prematurely, estrogen levels fall abruptly. We see:

• Increased cardiovascular risk

• Accelerated bone demineralization

• Cognitive changes

• Mood instability

• Reduced physical resilience

These are not theoretical risks. They are measurable, predictable outcomes. And they are, in many cases, preventable. 

There is no reliable screening for ovarian cancer. When it presents, it is often advanced. Risk-reducing surgery remains one of the most effective strategies we have. Yet I have patients who delay or avoid this surgery because they anticipate being left to navigate untreated surgical menopause.

This is an unintended consequence of our own ambiguity.

Somewhere along the way, a narrative took hold: Reduce cancer risk, or preserve quality of life. You can’t have one and not the other. The data suggests this is not a necessary choice; you can have both.

If you are a BRCA mutation carrier considering, or recovering from, oophorectomy:

• HRT should be part of the discussion

• Estrogen-only therapy, when appropriate, deserves consideration

• Risk assessment should be individualized, not reflexive

• And perhaps most importantly: The conversation should be informed by current evidence, not residual discomfort.

Of note: Not all women in these studies had risk-reducing mastectomy (RRM); in fact, the studies specifically focused on women who retained their breast tissue, which is precisely why breast cancer risk was the measurable outcome. The question of HRT safety after RRSO is most clinically relevant for women who have not had a bilateral mastectomy, those who retain breast tissue and therefore remain at risk for breast cancer. For women who have had both RRM and RRSO, the breast cancer concern with HRT is largely moot!

• Dr.Brenda Tapp Leonard ND