One of the most closely watched dose-de-escalation trials in early breast cancer has stopped enrolling. The regimen it is testing — low-dose tamoxifen taken every other day — is investigational and unproven: it is being studied in a trial, not offered as an approved alternative to standard endocrine therapy, and no outcome data have been reported.
According to the live ClinicalTrials.gov record, the Alliance for Clinical Trials in Oncology study LoTam (NCT06671912, Alliance A012301) is listed as SUSPENDED. The registry’s status module gives a single stated cause in its whyStopped field — “Amending protocol to increase sample size” — and records a last-update-posted date of June 8, 2026. Both fields were verified directly against the ClinicalTrials.gov API v2 status module; neither was present in the reduced registry payload first retrieved.
A narrow eligibility window — not breast cancer in general
LoTam does not apply to breast cancer broadly, and a reader should not infer it covers their own or a relative’s diagnosis. To enroll, patients must be postmenopausal, with hormone-receptor-positive, HER2-negative disease that is early-stage — the registry lists anatomic stage 0 through IIA, including ductal and lobular carcinoma in situ — and classified as molecular low-risk by a multigene assay.
The registry defines postmenopausal status by one of three routes: no spontaneous menses for at least a year; no menses for under a year with FSH and estradiol in the postmenopausal range per institutional standards; or prior bilateral surgical oophorectomy. Genomic eligibility requires a low-risk multigene score — an Oncotype DX recurrence score of 25 or below, MammaPrint low risk, or a Prosigna risk of recurrence of 40 or below — with both required to be low-risk if more than one assay was run.
LoTam is a randomized, open-label Phase 3 trial run by the Alliance with the National Cancer Institute, with a planned enrollment of 1,556 patients. It randomizes eligible women to low-dose tamoxifen taken orally every other day (Arm II) versus standard daily endocrine therapy — an aromatase inhibitor (anastrozole, letrozole, or exemestane) or standard-dose tamoxifen once daily (Arm I) — for up to five years.
A non-inferiority bet, with no answer yet
The primary endpoint is recurrence-free interval, tested for non-inferiority of low-dose tamoxifen against standard-of-care endocrine therapy over five years, with a stratified Cox hazard ratio reported against a one-sided 95% confidence interval. Secondary endpoints include endocrine-therapy nonadherence; physician-reported adverse events, among them fracture, osteoporosis, stroke and thromboembolism; patient-reported toxicities; invasive disease-free survival; and overall survival, with follow-up of up to ten years.
The suspension is a protocol amendment to enlarge the trial, per the registry — not a reported safety or efficacy signal. No results have been posted, so whether the lower dose is non-inferior remains unknown.
The trial first opened February 19, 2025; estimated primary completion is November 30, 2030. Because no efficacy or safety results exist, any judgment on whether the lower dose holds up is years away. This is a report on a trial’s registry status, not medical advice. Patients should not change or stop endocrine therapy based on an unproven regimen in a paused study, and should discuss treatment with their own oncologist.