Question explored with the scientific record
Est-ce que le tamoxifène protège les hommes du retour du cancer du sein et si oui de combien de pourcentage
The short version: tamoxifen is the standard of care for preventing recurrence in men with hormone-receptor-positive breast cancer, but the exact percentage of risk reduction is not known from high-quality male-specific trials.
The evidence for tamoxifen in men is thin and mostly borrowed from women. The ASCO guideline, the most authoritative source here, recommends tamoxifen for men with early-stage hormone-receptor-positive breast cancer, but it rates the evidence quality as low and the recommendation as "formal consensus" rather than data-driven [3]. That means experts agreed it should work based on biology and female data, not because they have good male-specific studies.
One small study of 24 men from 1999 reported a 5-year survival of 66% and a 10-year survival of 44%, but it did not isolate the effect of tamoxifen from other treatments [7]. A 2015 study of 38 men found a recurrence rate of 13.2% and a 5-year disease-free survival of 86.2% on tamoxifen, but there was no control group of men who did not take it [1]. That study also showed that men with a specific genetic variant (CYP2D6*4) that makes them poor tamoxifen metabolizers had a higher recurrence risk, meaning the drug's effectiveness varies by genetics [1, 2].
In women, the data is stronger. The NSABP P-1 prevention trial found tamoxifen reduced invasive breast cancer by 49% (RR 0.51) and ER-positive cancers by 69% (RR 0.31) [9]. The BIG 1-98 trial in postmenopausal women found a modest disease-free survival benefit for letrozole over tamoxifen (HR 0.82), but that was in women, not men [10].
| Population | Recurrence risk without tamoxifen | Recurrence risk with tamoxifen | Source |
|---|---|---|---|
| Men (small study, no control) | Not measured | 13.2% recurrence rate | [1] |
| Women (NSABP P-1 prevention trial) | ~2% per year | ~1% per year (49% reduction) | [9] |
| Women (BIG 1-98 adjuvant trial) | ~19% at 5 years | ~16% at 5 years (18% relative reduction) | [10] |
The real-world adherence data from a 2022 Norwegian study of 1192 patients (mostly women) showed that about 24% of patients do not adhere to tamoxifen, and only 55% persist for the full 5 years [5]. That matters because a drug you do not take cannot protect you.
My call: tamoxifen likely reduces recurrence risk in men with hormone-receptor-positive breast cancer, but the size of that reduction is unknown from male-specific data. The benefit is probably in the range seen in women (roughly 30-50% relative reduction), but that is an extrapolation, not a proven number for men. Confidence: low for the exact percentage in men; moderate for the general principle that tamoxifen helps.
Sources used 7
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CYP2D6*4 polymorphism: A new marker of response to hormonotherapy in male breast cancer?
This study investigates the association between CYP2D6*4 polymorphism and clinical outcomes in male breast cancer patients undergoing tamoxifen treatment, revealing that poorer metabolizers have a higher risk of recurrence and worse disease-free survival.
DOI: 10.1016/j.breast.2015.04.010 -
Potential Benefits of Pre-emptive PGx Testing in Male Breast Cancer Patients
Pre-emptive pharmacogenomic testing can guide adjuvant endocrine therapy in male breast cancer by identifying CYP2D6 poor metabolizers and prompting a switch from tamoxifen to an aromatase inhibitor, as illustrated by a case of recurrence.
DOI: 10.24926/iip.v10i4.2303 -
Management of Male Breast Cancer: ASCO Guideline
This ASCO guideline provides evidence-informed, formal consensus recommendations for the management of male breast cancer, covering adjuvant endocrine therapy, duration, toxicity management, imaging surveillance, metastatic treatment options, targeted therapies, genetics, follow…
DOI: 10.1200/jco.19.03120 -
Predictors of adherence and the role of primary non-adherence in antihormonal treatment of breast cancer
This population-based study of 1192 Norwegian patients with HR-positive breast cancer identifies adherence levels to adjuvant antihormonal therapy, specifies the prevalence of primary non-adherence, and outlines patient- and treatment-related predictors of adherence, highlightin…
DOI: 10.1186/s12885-022-10362-4 -
Carcinoma of the male breast: A review of adjuvant therapy
This study reviews the adjuvant therapy outcomes for male breast cancer patients treated at Royal Prince Alfred Hospital over a 13-year period, highlighting the prevalence of estrogen receptor positivity and the survival rates associated with different treatment modalities.
DOI: 10.1046/j.1440-1673.1999.00601.x -
Breast Cancer Chemoprevention: Current Approachesand Future Directions
Chemopreventive SERMs and AIs can reduce ER-positive breast cancer incidence in women at increased risk, but uptake is limited by adverse effects and implementation barriers; ER-negative prevention remains challenging; results vary by trial and subgroup.
DOI: 10.1007/s13669-011-0005-0 -
Five Years of Letrozole Compared With Tamoxifen As Initial Adjuvant Therapy for Postmenopausal Women With Endocrine-Responsive Early Breast Cancer: Update of Study BIG 1-98
In a updated analysis limited to continuous 5-year monotherapy arms of BIG 1-98, postmenopausal women with receptor-positive early breast cancer showed a modest but statistically significant improvement in disease-free survival with letrozole compared with tamoxifen, with simila…
DOI: 10.1200/JCO.2006.08.8617