Breast Cancer Chemoprevention: A Network Meta-Analysis of Randomized Controlled Trials

Simone Mocellin, Pierluigi Pilati, Marta Briarava, Donato Nitti

Research output: Contribution to journalArticlepeer-review


BACKGROUND: Several agents have been advocated for breast cancer primary prevention. However, few of them appear effective, the associated severe adverse effects limiting their uptake.

METHODS: We performed a comprehensive search for randomized controlled trials (RCTs) reporting on the ability of chemoprevention agents (CPAs) to reduce the incidence of primary breast carcinoma. Using network meta-analysis, we ranked CPAs based simultaneously on efficacy and acceptability (an inverse measure of toxicity). All statistical tests were two-sided.

RESULTS: We found 48 eligible RCTs, enrolling 271 161 women randomly assigned to receive either placebo or one of 21 CPAs. Aromatase inhibitors (anastrozole and exemestane, considered a single CPA class because of the lack of between-study heterogeneity; relative risk [RR] = 0.468, 95% confidence interval [CI] = 0.346 to 0.634), arzoxifene (RR = 0.415, 95% CI = 0.253 to 0.682), lasofoxifene (RR = 0.208, 95% CI = 0.079 to 0.544), raloxifene (RR = 0.572, 95% CI = 0.372 to 0.881), tamoxifen (RR = 0.708, 95% CI = 0.595 to 0.842), and tibolone (RR = 0.317, 95% CI = 0.127 to 0.792) were statistically significantly associated with a therapeutic effect, which was restricted to estrogen receptor-positive tumors of postmenopausal women (except for tamoxifen, which is active also during premenopause). Network meta-analysis ranking showed that the new selective estrogen receptor modulators (SERMs) arzoxifene, lasofoxifene, and raloxifene have the best benefit-risk ratio. Aromatase inhibitors and tamoxifen ranked second and third, respectively.

CONCLUSIONS: These results provide physicians and health care regulatory agencies with RCT-based evidence on efficacy and acceptability of currently available breast cancer CPAs; at the same time, we pinpoint how much work still remains to be done before pharmacological primary prevention becomes a routine option to reduce the burden of this disease.

Original languageEnglish
JournalJournal of the National Cancer Institute
Issue number2
Publication statusPublished - Feb 2016


  • Adult
  • Aged
  • Anticarcinogenic Agents
  • Antineoplastic Agents, Hormonal
  • Aromatase Inhibitors
  • Breast Neoplasms
  • Female
  • Humans
  • Middle Aged
  • Norpregnenes
  • Piperidines
  • Postmenopause
  • Primary Prevention
  • Pyrrolidines
  • Raloxifene Hydrochloride
  • Randomized Controlled Trials as Topic
  • Risk Assessment
  • Selective Estrogen Receptor Modulators
  • Tamoxifen
  • Tetrahydronaphthalenes
  • Thiophenes
  • Journal Article
  • Meta-Analysis


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