Hormonal management after risk-reducing surgery in BRCA-mutated triple-negative breast cancer survivors

Abstract

Premenopausal women carrying a BRCA1 or BRCA2 mutation are frequently advised to undergo risk-reducing bilateral salpingo-oophorectomy (BSO) to lower their significantly increased lifetime risk of ovarian cancer. However, this procedure induces abrupt estrogen deprivation, resulting in premature menopause with well-documented consequences including vasomotor symptoms (e.g., hot flashes, night sweats), urogenital atrophy, and long-term risks such as osteoporosis, cardiovascular disease, and cognitive decline (Nelson in Lancet 371(9614):760–770, 2008; Shuster et al. in Maturitas 65(2):161–166, 2010). To alleviate symptoms and prevent sequelae, hormone replacement therapy (HRT) remains the most effective intervention. However, the issue becomes complex when the patient has a personal history of triple-negative breast cancer (TNBC). Although TNBC lacks hormone receptor expression, systemic HRT has traditionally been contraindicated in breast cancer survivors, as early studies indicated an increased risk of recurrence with hormone therapy, even in receptor-negative subtypes (Kenemans et al. Lancet Oncol 10(2):135–146, 2009a). This leads to a critical question: Is HRT appropriate in BRCA mutation carriers with a history of TNBC following BSO, and if so, under what clinical conditions? What do current international guidelines, evidence, and expert recommendations suggest?

Guideline recommendations and the risk of early estrogen deprivation

Multiple large-scale studies have demonstrated that menopause before the age of 40—whether spontaneous or surgically induced—is associated with a significantly increased risk of cardiovascular disease and osteoporotic fractures.

A meta-analysis of 32 cohort studies encompassing over 300,000 women (Zhu et al., Lancet Public Health, 2019) revealed that women who experienced menopause before the age of 40 had a 1.5-fold increased risk of developing coronary artery disease (CAD). Moreover, their risk of myocardial infarction was elevated by approximately 40–60%, depending on the presence of additional cardiovascular risk factors. The study further demonstrated that the risk of CAD increases incrementally with each 5-year decrease in age at menopause (Parker et al. 2009).

These findings were supported by the Nurses’ Health Study, a large prospective cohort from the United States. Women who underwent surgical menopause prior to age 40 and did not receive hormone replacement therapy (HRT) exhibited a nearly twofold increased risk of cardiovascular mortality compared to age-matched women with natural menopause (Shuster et al. 2008). These associations are thought to be primarily driven by the loss of estrogen’s protective vascular effects, including favorable modulation of lipid profiles, endothelial function, and prevention of atherosclerotic plaque formation (Bjelland et al. 2020).

Similarly, early estrogen deprivation is a well-established risk factor for rapid bone loss and fragility fractures. Women experiencing menopause before age 40 may lose 2–3% of their bone mineral density annually, especially in trabecular bone-rich sites such as the lumbar spine and proximal femur (Bjelland et al. 2020).

A Swedish population-based cohort study (2020) found that women with early menopause had a 1.3- to 1.8-fold increased risk of both vertebral and hip fractures (Hannan et al. 2000). Furthermore, the EPIC study reported a 20% increase in fracture risk for every 5-year advancement in menopausal age (National Comprehensive Cancer Network (NCCN) 2022; ESMO Guidelines Committee 2022). Estrogen deficiency disrupts the normal balance of bone remodeling, and without adequate HRT, the risk of developing osteopenia by age 40–45 and overt osteoporosis by age 50 and beyond is substantially elevated (Bjelland et al. 2020).

Guideline recommendations (NCCN, ESMO, AGO, etc.)

International guidelines are unanimous in stating that for BRCA mutation carriers without a personal history of breast cancer, short-term HRT following premenopausal risk-reducing BSO (RRBSO) should be considered or recommended.

The National Comprehensive Cancer Network (NCCN) clarified in its 2022 guidelines that HRT should be considered in premenopausal BRCA1/2 carriers without a personal breast cancer diagnosis, with continuation until the age of natural menopause (~ 50–52 years) (National Comprehensive Cancer Network (NCCN) 2022; Rebbeck et al. 2005). Similarly, the European Society for Medical Oncology (ESMO) Clinical Practice Guidelines (2022) state that available data suggest HRT is safe in this population. Use is considered acceptable up to the age of 45, particularly to improve quality of life. HRT use beyond age 50 should be individualized and may be more acceptable in women who have undergone prophylactic mastectomy (ESMO Guidelines Committee 2022).

Therefore, short-term HRT following RRBSO may be offered (Level of Evidence C) if no contraindications are present and with appropriate counseling (ESMO Guidelines Committee 2022).

In Germany, national recommendations mirror this consensus. The S3 Guideline (highest level evidence-based German guideline) on Hereditary Breast and Ovarian Cancer and the AGO Guidelines (from the German Gynecological Oncology Group) emphasize that risk-reducing BSO should not be postponed due to concerns regarding HRT (Wöckel et al. 2021; Arbeitsgemeinschaft Gynäkologische Onkologie (AGO) 2023). Premenopausal BRCA mutation carriers should be offered adequate HRT after BSO to address climacteric symptoms and prevent sequelae related to estrogen deficiency (Wöckel et al. 2021). The recommended regimens include transdermal or oral 17-β-estradiol or conjugated estrogens. In women with an intact uterus, endometrial protection with a progestogen (e.g., micronized progesterone) is required (Wöckel et al. 2021; Stuenkel et al. 2015). Ideally, HRT should begin immediately post-oophorectomy and continue until natural menopausal age, with routine follow-up (including breast imaging depending on breast status) (Arbeitsgemeinschaft Gynäkologische Onkologie (AGO) 2023).

In contrast, for patients with a history of breast cancer, including TNBC, the use of systemic HRT is contraindicated in virtually all international guidelines.

The NCCN explicitly lists a personal history of breast cancer as a contraindication to HRT (National Comprehensive Cancer Network (NCCN) 2022). Similarly, the Society of Obstetricians and Gynaecologists of Canada (SOGC) states that systemic menopausal hormone therapy is contraindicated in women with any history of breast cancer, regardless of receptor status (high-quality evidence) (The Society of Obstetricians and Gynaecologists of Canada (SOGC) 2021). Most guidelines therefore recommend non-hormonal strategies for managing menopausal symptoms in this population (The Society of Obstetricians and Gynaecologists of Canada (SOGC) 2021; North American Menopause Society (NAMS) 2022).

Notably, no guideline explicitly supports HRT in women with a history of TNBC, even though these tumors are estrogen-receptor negative. Hence, TNBC survivors are generally managed with the same caution as those with hormone-receptor-positive disease (Table 1).

Table 1.

International guideline recommendations on HRT in BRCA mutation carriers (as of 2022/23)

Guideline (2022/23)	HRT after BSO in BRCA mutation carriers without prior breast cancer	HRT in BRCA mutation carriers after breast cancer (including TNBC)
NCCN (USA)	HRT is indicated/recommended until the age of natural menopause in premenopausal BRCA1/2 carriers without a personal history of breast cancer. Perioperative menopause counseling is advised	HRT is not recommended in women with a history of breast cancer (contraindicated), including TNBC. Non-hormonal symptom control should be prioritized
ESMO (Europe)	HRT after risk-reducing BSO may be offered (Level C), particularly in younger women (< 45 years) to improve quality of life. Use until ~ 50 years is considered safe; beyond that only with individualized risk assessment (preferably after prophylactic mastectomy)	No explicit recommendation for HRT after breast cancer; generally discouraged to contraindicated. Systemic MHT usually to be avoided; local treatments preferred
AGO/DGGG (Germany)	Clear recommendation not to withhold HRT in BRCA carriers after premenopausal BSO. Early BSO should not be delayed due to HRT concerns. The benefits of HRT (symptom relief, prevention of osteoporosis and CVD) outweigh potential risks; no increased breast cancer risk observed	Systemic HRT is contraindicated after breast cancer (including TNBC). Non-hormonal therapies for menopausal symptoms are recommended; HRT may be considered only in strictly selected cases following interdisciplinary evaluation
Menopause Society (NAMS/JOGC)	Menopausal hormone therapy does not significantly increase breast cancer risk in BRCA carriers after RRSO (moderate evidence). Thus, HRT is considered acceptable until ~ age 50, preferably with estrogen alone if possible	Systemic MHT is absolutely contraindicated in women with any history of breast cancer (high-quality evidence). Non-hormonal options are the preferred first-line therapy for symptom management

Comparison of key guideline recommendations on HRT in BRCA mutation carriers. Left column: HRT after BSO in BRCA carriers without prior breast cancer; Right column: HRT in BRCA mutation carriers after breast cancer (including TNBC). BSO bilateral salpingo-oophorectomy, RRSO risk-reducing salpingo-oophorectomy, MHT menopausal hormone therapy

In summary:

• Without a personal history of breast cancer, HRT is clearly recommended for BRCA mutation carriers following RRBSO.

• With a history of TNBC, HRT remains highly controversial and generally not recommended, unless in very exceptional, individualized cases.

Of note, the German Society for Radiation Oncology (DEGRO) has not issued separate recommendations regarding HRT in this setting. German multidisciplinary consensus guidelines (AGO, DGGG) align with the aforementioned view: HRT should be avoided after breast cancer, and non-hormonal alternatives should be prioritized for managing menopausal symptoms following curative oncologic treatment (Wöckel et al. 2021; Stuenkel et al. 2015).

In women with an intact uterus, these guidelines all remind clinicians that a progestogen must be included for endometrial protection. Notably, no major guideline currently recommends prophylactic hysterectomy as a routine component of risk-reducing surgery in BRCA carriers. NCCN and ACOG do not list routine hysterectomy as part of standard management for BRCA1/2 mutation carriers, instead advising that hysterectomy be reserved for those with additional indications (such as uterine risk factors or the need to take tamoxifen) The ESMO guidelines explicitly state that hysterectomy is not routinely indicated at RRSO unless there are other risk factors for uterine cancer (e.g. MLH1/MSH2 mutations, complex atypical hyperplasia) or significant benign uterine disease. The Society of Gynecologic Oncology (SGO) also endorses an individualized approach: they acknowledge a small increased risk of serous uterine carcinoma in BRCA1 carriers, and that some women choose concurrent hysterectomy to maximize risk reduction or to facilitate estrogen-only HRT, but they emphasize weighing this against the slightly higher surgical risk and recovery time. SGO and ACOG guidance conclude that the choice of hysterectomy “should be based on a full discussion of risks and potential benefits” between the patient and surgeon, rather than applied universally.

Evidence base: safety and efficacy of HRT

HRT in BRCA1/2 mutation carriers without a breast cancer diagnosis

Current evidence regarding the safety of HRT in BRCA mutation carriers without a personal history of breast cancer is reassuring. Several studies have demonstrated that short-term HRT after prophylactic oophorectomy does not increase the risk of breast cancer.

A prospective multicenter study by Kotsopoulos et al. involving 872 BRCA1 mutation carriers who underwent risk-reducing salpingo-oophorectomy (RRSO) found no significant difference in breast cancer incidence between HRT users and non-users (10.3% vs. 10.7%; p = 0.86) (Kotsopoulos et al. 2016). Interestingly, in women who underwent oophorectomy before age 45, each additional year of estrogen-only HRT use was associated with an 18% relative risk reduction in breast cancer. In contrast, a non-significant increase (+ 14% per year) was observed in women using progestin-only therapy (Kotsopoulos et al. 2016).

These findings suggest that estrogen-only therapy—which is feasible in women who have undergone hysterectomy—may be preferable in this population, whereas the addition of progestins does not appear to reduce breast cancer risk.

A 2020 meta-analysis by Marchetti et al., including ~ 1100 BRCA mutation carriers, supported the overall safety of HRT after RRSO (Marchetti et al. 2020). Breast cancer incidence was not significantly different between estrogen-only and combined (estrogen + progestin) users, though the odds ratio favored estrogen monotherapy (OR 0.53; 95% CI 0.25–1.15) (Marchetti et al. 2020).

Additionally, a case–control study in BRCA1 carriers found no increased risk of breast cancer associated with HRT use (Eisen et al. 2008). Importantly, the study by Rebbeck et al. (2009) confirmed that the protective effect of RRSO on breast cancer risk was not negated by subsequent HRT use. Together, these findings support the guideline consensus that HRT can be considered both safe and beneficial in healthy BRCA mutation carriers post-oophorectomy.

2023 Depypere’s Review about Treatment of women with BRCA mutation (Depypere 2023) show that HT does not significantly increase breast cancer risk in BRCA1 mutation carriers, including those undergoing risk-reducing bilateral salpingo-oophorectomy (RRBSO). This holds true for both natural and surgical menopause.

Although data are limited, HT is considered safe before age 50 following RRBSO. In fact, the absence of increased risk is even more evident in women who also undergo prophylactic mastectomy. When combined with immediate reconstruction, HT may offer both safety and quality of life, supporting its use post-surgery.

HRT in patients with prior history of TNBC

The evidence for HRT use in patients with a history of TNBC is significantly more limited and largely indirect. Large randomized trials investigating HRT in breast cancer survivors, such as HABITS, were terminated early due to signals of increased cancer recurrence with HRT—although most participants in these trials had hormone receptor-positive disease (Holmberg 2004).

In an analysis of the HABITS trial Homberg et al. (2004) found no clear increase in distant metastases under HRT, though an increase in local and contralateral recurrences was observed. In the HABITS trial, there was significant undertreatment with tamoxifen, particularly among the subgroup of women with estrogen receptor-positive tumors—which accounted for more than 80% of the participants. When adjuvant therapy is inadequate, it is not surprising to observe a higher rate of recurrence upon administration of HRT.

In contrast, the parallel Stockholm trial reported no significant increase in recurrences with HRT (Fahlén et al. 2013) Even after 10 years of follow-up, Stockholm found no overall difference in new breast cancer events between the HRT and control groups, although the HRT arm showed a higher incidence of contralateral (likely estrogen receptor-positive) breast cancers.

Data specific to ER-negative or TNBC subgroups are rare and statistically underpowered, often due to small sample sizes and wide confidence intervals (Holmberg 2004; Fahlen et al. 2013).

A recent systematic review (2021) reported that systemic HRT may increase the risk of recurrence in breast cancer survivors—especially in those with prior hormone receptor-positive tumors (Furlanetto et al. 2021). For hormone receptor-negative tumors (i.e., TNBC), the evidence remains inconsistent and inconclusive (Furlanetto et al. 2021).

In an analysis of the HABITS trial Homberg et al. (2004) found no clear increase in distant metastases under HRT, though an increase in local and contralateral recurrences was observed.

Given the lack of robust prospective data, the safety of HRT in TNBC survivors remains unproven. Although some retrospective case series suggest that short-term HRT in TNBC patients with menopausal symptoms may not increase recurrence rates (Mueck et al. 2002), these findings are anecdotal and insufficient for broad clinical recommendation.

Thus, in the absence of definitive data, international guidelines continue to discourage systemic HRT in women with a history of TNBC, advocating instead for non-hormonal alternatives (The Society of Obstetricians and Gynaecologists of Canada (SOGC) 2021).

Risk of second primary breast cancer after TNBC and the influence of HRT

Breast cancer survivors generally have an increased risk of developing a second primary tumor in the contralateral breast. A large SEER registry study (USA) found that the risk of a contralateral breast cancer was more than twice as high compared to the general population (Standardized Incidence Ratio ~ 2.2) (Li et al. 2009). Notably, younger women with estrogen receptor (ER)-negative primary tumors, such as TNBC, carry a higher risk of developing a second primary tumor compared to those with ER-positive tumors. Within 5 years, the cumulative incidence of a contralateral tumor was approximately 1.9% for patients with an ER-negative first tumor, versus about 1.0% in those with an ER-positive primary cancer (Li et al. 2009).

One reason is that patients with ER-positive breast cancer typically receive adjuvant endocrine therapy (e.g., tamoxifen or aromatase inhibitors), which also provides prophylactic protection against new tumors. TNBC patients, lacking hormone receptor targets, do not receive such treatment.

Crucially, in the context of hormone replacement therapy (HRT): if TNBC survivors are given exogenous hormones, these may promote the development of hormone-sensitive second cancers. In fact, menopausal HRT has been shown to significantly increase the risk of ER-positive breast cancers in the general population—much more so than triple-negative subtypes (Beral and Million Women Study Collaborators 2003). In other words, HRT tends to promote luminal (hormone-dependent) breast cancer (Beral and Million Women Study Collaborators 2003).

Thus, there is a plausible risk that a woman with a history of TNBC might not develop a recurrent TNBC under HRT, but rather a new ER-positive tumor, which could be initiated or promoted by exogenous hormones.

Although first and second breast tumors often share the same receptor status, registry data show that up to 30% of women with an initially ER-negative tumor go on to develop an ER-positive second primary tumor in the contralateral breast (NHS Vale of York Clinical Commissioning Group 2021). This non-negligible residual risk of a hormone-sensitive second breast cancer—following an originally hormone-insensitive TNBC—supports the caution against HRT in this population (NHS Vale of York Clinical Commissioning Group 2021).

Even metastatic recurrences of originally ER-negative tumors can unexpectedly express ER positivity in about 8% of cases (NHS Vale of York Clinical Commissioning Group 2021). This suggests that hormonal influences may still play a role later in disease progression, even in patients initially classified as hormone receptor–negative. Although the biological mechanisms behind this are not fully understood—possibly involving receptor conversion in subclones or the development of an entirely new tumor—it contributes to the hypothesis that HRT cannot be considered entirely safe even for TNBC survivors.

BRCA1 vs. BRCA2: mutation-specific considerations

Differences between BRCA1 and BRCA2 mutation carriers are most evident in tumor biology and timing of disease, rather than in the response to HRT.

BRCA1 carriers are more likely to develop early-onset triple-negative breast cancer, and face a higher risk of ovarian cancer beginning in their mid-30 s. Consequently, BSO is typically recommended by age 35 in this group, which often results in very early menopause and increased need for HRT (Domchek et al. 2010).

Indeed, many of the cited HRT safety studies—such as Kotsopoulos et al.—primarily involved BRCA1 carriers, with no observed increase in breast cancer risk under HRT (Kotsopoulos et al. 2016).

In contrast, BRCA2 mutation carriers generally present with later-onset, often hormone receptor-positive breast cancers. Risk-reducing BSO is often deferred to age 40–45, and if breast cancer has already occurred, it is commonly treated with endocrine therapy, rendering HRT unsuitable.

Although TNBC is less frequent in BRCA2 carriers, the approach to HRT in this subgroup is similar to that for BRCA1-associated TNBC: extreme caution, if not outright avoidance.

Notably, there is no convincing evidence of differential risk from HRT between BRCA1 and BRCA2 mutation carriers. Most studies and meta-analyses pooled both mutations and showed no statistically significant adverse effect of HRT (Marchetti et al. 2020; Eisen et al. 2008).

Some analyses suggest a greater potential benefit of estrogen-only therapy in BRCA1 carriers, and no difference in risk in BRCA2 carriers under combined therapy—but these findings are not definitive (Marchetti et al. 2020).

Importantly, BRCA1 carriers more often undergo concurrent hysterectomy, which allows for estrogen-only therapy, potentially further lowering breast cancer risk (Kotsopoulos et al. 2016). Conversely, BRCA2 carriers usually retain the uterus, requiring combined HRT (estrogen + progestin), which may slightly increase breast risk.

In practice, tumor biology (i.e., hormone receptor status) and personal cancer history remain far more relevant to HRT decision-making than mutation subtype.

Alternatives to systemic HRT in high-risk patients

Given the restrictions surrounding systemic HRT in women with a history of breast cancer—particularly TNBC—non-hormonal strategies play a crucial role in symptom management and long-term health preservation.

(a) Non-hormonal treatment of vasomotor symptoms

Numerous pharmacologic agents have demonstrated efficacy in managing vasomotor symptoms such as hot flashes and night sweats. First-line options include low-dose antidepressants, particularly SSRIs and SNRIs (e.g., venlafaxine, escitalopram), which can reduce symptom frequency and severity by 50–60% (Loprinzi et al. 2010).

Similarly, elinzanetant (a dual NK1/3 antagonist) has shown significant efficacy in reducing vasomotor symptoms in breast cancer patients receiving endocrine therapy A phase III trial of fezolinetant is currently ongoing in breast cancer survivors (HIGHLIGHT-1 whereas the elinzanetant trial (OASIS-4) has been completed with positive results (OASIS 4 2025).

Other options include gabapentin, which is especially effective at night, and clonidine, an antihypertensive agent with moderate efficacy. A newly approved therapy, fezolinetant, a neurokinin-3 receptor antagonist, has shown promising results in reducing menopausal symptoms without affecting breast tissue. Approved in the U.S. in 2023, it is pending approval in the EU (Simon et al. 2023).

These therapies may be used individually or in combination, offering substantial symptom relief without the oncologic risk associated with systemic hormones.

(b) Local estrogen therapy for genitourinary symptoms

For women experiencing urogenital symptoms such as vaginal dryness, dyspareunia, or recurrent urinary tract infections, low-dose local estrogen therapy (e.g., creams, ovules, estriol-releasing vaginal rings) is considered both highly effective and safe (Farrell 2021). Systemic absorption is minimal, and several guidelines now support cautious use of vaginal estrogen even in breast cancer survivors, pending oncologic approval.

Non-hormonal options include vaginal moisturizers and lubricants, and in some cases DHEA suppositories (prasterone) to support mucosal regeneration (Farrell 2021).

(c) Bone protection and cardiovascular prevention

In the absence of systemic HRT, proactive management of bone and cardiovascular health is essential. Early bone mineral density testing (DXA scan) should be conducted, followed by calcium and vitamin D supplementation.

Depending on results, bisphosphonates (e.g., alendronate) or denosumab may be prescribed for osteoporosis prevention.

These treatments not only prevent fractures but may also reduce the risk of bone metastases and possibly overall cancer recurrence, particularly bisphosphonates in postmenopausal breast cancer survivors (by contrast, no benefit from adjuvant bisphosphonates has been observed in premenopausal patients (Early Breast Cancer Trialists' Collaborative Group (EBCTCG) 2015).

These agents also appear to reduce the risk of bone metastases and potentially overall recurrence risk in breast cancer survivors (Coleman et al. 2020).

Lifestyle modifications including aerobic and resistance exercise, weight management, and smoking cessation are critical for cardiovascular protection, particularly in women facing long-term estrogen deficiency (Khoudary et al. 2020).

According to the National Institute on Alcohol Abuse and Alcoholism (NIAAA) a heart-healthy lifestyle—no smoking, a balanced diet—is recommended for all patients and becomes even more critical in the absence of protective hormones. Limiting alcohol consumption is also advisable, given that even low levels of alcohol intake have been linked to higher breast cancer risk.

(d) SERMs and endocrine modulators

In select cases, selective estrogen receptor modulators (SERMs) such as raloxifene may be used. Raloxifene acts as an estrogen antagonist in breast tissue and an agonist in bone, reducing breast cancer risk while preserving bone mass (Vogel 2009). It is approved for osteoporosis treatment and cancer prevention in high-risk postmenopausal women.

However, raloxifene does not alleviate menopausal symptoms—and may worsen hot flashes—making it unsuitable for symptom control. Another agent, tibolone, once considered a hormone replacement alternative, was found to increase recurrence rates in the LIBERATE trial and is not recommended in breast cancer survivors (Kenemans et al. 2009b).

(e) Psychosocial and complementary approaches

Complementary approaches such as cognitive-behavioral therapy, mindfulness, acupuncture, and herbal supplements (e.g., soy isoflavones, red clover, black cohosh) have shown variable benefit. Evidence remains limited and heterogeneous; while some women experience relief, others do not (Nedrow et al. 2006).

These therapies may be used as adjunctive measures, especially when medical options are limited. Referral to menopause specialists, sexual health counselors, or patient support groups is often beneficial in improving quality of life after early menopause.

Clinical decision-making framework

The decision to initiate HRT in BRCA mutation carriers with prior TNBC must follow a structured, individualized approach.

Step 1: patient selection

Only carefully selected patients should be considered for HRT. These include:

• TNBC survivors with ER/PR-negative tumors, no evidence of disease, and complete remission for several years

• Women with severe menopausal symptoms or early signs of osteoporosis

• Those with bilateral mastectomy, significantly reducing the risk of new primary breast cancer

HRT remains contraindicated in women with ongoing disease, hormone receptor-positive cancers, or high residual breast tissue.

Step 2: risk–benefit counseling

Patients must undergo detailed counseling outlining the known benefits of HRT—relief of symptoms, preservation of bone and cardiovascular health—and the uncertainty regarding recurrence risk in TNBC survivors.

Shared decision-making is essential. If the patient informedly requests HRT despite potential risks, this is viewed as a compassionate exception, not standard of care.

Step 3: HRT protocol (in exception cases)

If HRT is initiated:

• Use the lowest effective dose for the shortest duration

• Transdermal 17β-estradiol is preferred for systemic therapy

• If the uterus is intact, use micronized progesterone or a levonorgestrel intrauterine system to reduce systemic progestin exposure

• Schedule frequent follow-up: every 3–6 months, including clinical exams and imaging (mammogram/MRI or chest wall ultrasound)

• Discontinue HRT by natural menopausal age (~ 50–52 years)

Transdermal estrogen:

Lower risk of venous thromboembolism (VTE): Unlike oral estrogen, transdermal estrogen avoids first-pass metabolism in the liver, which reduces its impact on clotting factors. This significantly lowers the risk of VTE and stroke, particularly in women with cardiovascular risk factors.

Stable hormone levels: Transdermal delivery offers more consistent estrogen levels compared to oral formulations, minimizing fluctuations that may contribute to side effects.

Micronized progesterone:

Reduced risk of breast cancer: Micronized progesterone, a bioidentical hormone, has been associated with a lower risk of breast cancer compared to synthetic progestins like medroxyprogesterone acetate.

Cardiometabolic neutrality: It does not adversely affect lipid profiles or glucose metabolism to the extent that synthetic progestins might.

Step 4: if HRT is declined

If the patient (or medical team) opts against HRT—which is the default recommendation in TNBC cases—then the full range of alternative strategies (previously discussed) must be implemented.

This includes:

• Proactive symptom management (e.g., venlafaxine for hot flashes, local estrogen creams for vaginal atrophy, good sleep hygiene, and potentially melatonin or gabapentin for sleep disturbances); limiting alcohol intake is also recommended, given even low alcohol use increases breast cancer risk

• Regular bone density scans (DXA) with early intervention if bone loss is detected (for example, initiating bisphosphonate therapy).

• Lifestyle changes for cardiovascular prevention (exercise, diet, weight control); moderation of alcohol consumption is advised, since even modest drinking heightens breast cancer risk

Referral to a specialized menopause or endocrinology clinic may be appropriate to develop a personalized management plan.

It is critical to reassure the patient that she is not being left without options just because HRT is off the table—there is a bundle of effective measures available.

Additionally, consideration should be given to psychological support, as the abrupt onset of menopause and fear of cancer recurrence can create significant emotional stress.

In most TNBC cases, HRT is appropriately avoided. Instead:

• Use non-hormonal medications for symptom relief

• Monitor bone density regularly and treat osteopenia/osteoporosis aggressively

• Emphasize lifestyle, diet, exercise, and psychosocial support

• Consider referral to endocrinology or menopause clinics

Conclusion and clinical implications

HRT in premenopausal BRCA mutation carriers after BSO is a well-supported strategy in cancer-free women, shown to improve quality of life and reduce long-term health risks, with no evidence of increased breast cancer incidence (Kotsopoulos et al. 2016; Marchetti et al. 2020; Eisen et al. 2008; Rebbeck et al. 2009).

In contrast, for women with a history of TNBC, especially those with residual breast tissue, systemic HRT remains controversial and is largely contraindicated by current guidelines (National Comprehensive Cancer Network (NCCN) 2022; The Society of Obstetricians and Gynaecologists of Canada (SOGC) 2021; Furlanetto et al. 2021).

Nevertheless, select individual cases—such as young TNBC survivors with bilateral mastectomy and disabling symptoms—may justify a personalized, time-limited HRT trial under close multidisciplinary supervision.

Ultimately, treatment decisions must balance oncologic safety with patient well-being, prioritizing evidence-based alternatives where needed. Future research, such as prospective registries or safer non-hormonal therapies, may provide more clarity.

Until then, the guiding principle should be:

“When in doubt, choose safety—but never ignore quality of life.”

Author contributions

I.J. Wrote main manuscript text, D.C. prepared Abstract. All authors reviewed the manuscript.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Competing interests

The authors declare no competing interests.