Paper · 33761995

Comparative effectiveness of first-line palbociclib plus letrozole versus letrozole alone for HR+/HER2- metastatic breast cancer in US real-world clinical practice.

DeMichele A and 10 others. Breast Cancer Res, 2021. Cited by 105 papers, by iCite.

11 sourcespapers-2026-11-12-0.1.0

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ConductScience Library. Comparative effectiveness of first-line palbociclib plus letrozole versus letrozole alone for HR+/HER2- metastatic breast cancer in US real-world clinical practice. Papers, record 33761995. Release papers-2026-11-12-0.1.0, 12 Nov 2026. https://conductscience.org/library/papers/33761995

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Paper

PubMed's record of the paper, with iCite's citation figures. No abstract is shown.

Title: Comparative effectiveness of first-line palbociclib plus letrozole versus letrozole alone for HR+/HER2- metastatic breast cancer in US real-world clinical practice.; PubMed
Journal: Breast Cancer Res; PubMed
Year: 2021; PubMed
Publication types: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't; PubMed
PubMed: https://pubmed.ncbi.nlm.nih.gov/33761995/; PubMed
DOI: https://doi.org/10.1186/s13058-021-01409-8; PubMed
PMC: https://pmc.ncbi.nlm.nih.gov/articles/PMC7989035/; PubMed
The journal: https://conductscience.org/library/journal-index/100927353; PubMed
Citations, by iCite: 105; iCite
Relative citation ratio, by iCite: 5.46; iCite
Revised in PubMed: 2026-01-27; PubMed

Authors11

The authors in the order PubMed's record lists them, with the ORCID iDs it states.

Order	Author	Forename	ORCID iD
1	DeMichele A	Angela	https://orcid.org/0000-0003-1297-4251
2	Cristofanilli M	Massimo	https://orcid.org/0000-0002-4194-7175
3	Brufsky A	Adam	https://orcid.org/0000-0001-8080-7960
4	Liu X	Xianchen
5	Mardekian J	Jack	https://orcid.org/0000-0003-4851-5161
6	McRoy L	Lynn
7	Layman RM	Rachel M	https://orcid.org/0000-0002-8663-0331
8	Emir B	Birol
9	Torres MA	Mylin A
10	Rugo HS	Hope S

1 to 10 of 11Source PubMed

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Topics17

NLM's MeSH indexing of the paper, its major topics first.

MeSH term	Major
Antineoplastic Combined Chemotherapy Protocols	Major topic
Breast Neoplasms	Major topic
Letrozole	Major topic
Piperazines	Major topic
Pyridines	Major topic
Aged
Aromatase Inhibitors
Female
Humans
Middle Aged
Progression-Free Survival
Protein Kinase Inhibitors
Erb-b2 Receptor Tyrosine Kinases
Receptors, Estrogen
Receptors, Progesterone
Retrospective Studies
Survival Rate

Source PubMed

Grants0

Each grant PubMed's record writes, matched to the NIH project NIH's grant and paper links name for this paper, and each of those links the record does not write.

None in this release.

Trials1

The trials whose ClinicalTrials.gov record lists the paper, and the trial numbers the paper's PubMed record names.

Trial	Title	The trial lists it as	Named in the paper's record
NCT04176354	Real-world Treatment Patterns and Effectiveness of Palbociclib and AI Therapy	Derived from the trial	Yes

Source ClinicalTrials.gov

Comments and corrections0

PubMed's comments and corrections, NLM's own indexing: retractions first, then expressions of concern, errata and updates, and comments last.

None in this release.

References23

The papers the reference list in PubMed's record names, those in our copy of PubMed, in the list's order.

Order	PMID	Title	Journal	Year	In Papers	Source
1	30,392,115	Palbociclib in combination with fulvestrant in patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer: PALOMA-3 subgroup analysis of Japanese patients.	Int J Clin Oncol	2019	https://conductscience.org/library/papers/30392115	PubMed
2	24,122,911	The use of propensity score methods with survival or time-to-event outcomes: reporting measures of effect similar to those used in randomized experiments.	Stat Med	2014	https://conductscience.org/library/papers/24122911	PubMed
3	35,172,519	Real-World Evidence and Randomized Studies in the Precision Oncology Era: The Right Balance.	JCO Precis Oncol	2017	https://conductscience.org/library/papers/35172519	PubMed
4	25,524,798	The cyclin-dependent kinase 4/6 inhibitor palbociclib in combination with letrozole versus letrozole alone as first-line treatment of oestrogen receptor-positive, HER2-negative, advanced breast cancer (PALOMA-1/TRIO-18): a randomised phase 2 study.	Lancet Oncol	2015	https://conductscience.org/library/papers/25524798	PubMed
5	29,756,355	Development and Validation of a High-Quality Composite Real-World Mortality Endpoint.	Health Serv Res	2018	https://conductscience.org/library/papers/29756355	PubMed
6	30,632,023	Palbociclib plus letrozole as first-line therapy in estrogen receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer with extended follow-up.	Breast Cancer Res Treat	2019	https://conductscience.org/library/papers/30632023	PubMed
7	27,217,461	Endocrine Therapy for Hormone Receptor-Positive Metastatic Breast Cancer: American Society of Clinical Oncology Guideline.	J Clin Oncol	2016	https://conductscience.org/library/papers/27217461	PubMed
8	26,238,958	Moving towards best practice when using inverse probability of treatment weighting (IPTW) using the propensity score to estimate causal treatment effects in observational studies.	Stat Med	2015	https://conductscience.org/library/papers/26238958	PubMed
9	27,959,613	Palbociclib and Letrozole in Advanced Breast Cancer.	N Engl J Med	2016	https://conductscience.org/library/papers/27959613	PubMed
10	26,030,518	Palbociclib in Hormone-Receptor-Positive Advanced Breast Cancer.	N Engl J Med	2015	https://conductscience.org/library/papers/26030518	PubMed

1 to 10 of 23

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Cited by86

The papers in our copy of PubMed whose reference list names this one, newest first. iCite, which reads more sources, counts 105 citations.

PMID	Title	Journal	Year	In Papers	Source
42,973,915	Safety-guided selection of CDK4/6 inhibitors in HR+/HER2- metastatic breast cancer: toxicity profiles, dose modification, and clinical risk-benefit considerations.	Ther Adv Drug Saf	2026	https://conductscience.org/library/papers/42973915	PubMed
42,883,756	Identification of a Conserved Temporal Molecular Response Signature to CDK4/6 Inhibition Through Multi-Omics Integration Across Cancer Cell Lines.	Int J Mol Sci	2026	https://conductscience.org/library/papers/42883756	PubMed
42,780,725	First-line CDK4/6 inhibitor treatment of HR-positive, HER2-negative metastatic breast cancer: real-world data from Ho Chi Minh City Oncology Hospital, Vietnam.	Front Oncol	2026	https://conductscience.org/library/papers/42780725	PubMed
42,780,561	Treatment Patterns and Clinical Outcomes Among Patients Receiving Palbociclib Combinations for Hormone Receptor-Positive (HR+)/Human Epidermal Growth Factor Receptor 2-Negative (HER2-) Advanced/Metastatic Breast Cancer in the Arabian Gulf Region: A Retrospective Study (TREASURE Study).	Int J Breast Cancer	2026	https://conductscience.org/library/papers/42780561	PubMed
42,654,366	First-Line Palbociclib/Letrozole Versus Ribociclib/Letrozole in Postmenopausal HR-Positive/HER2-Negative Metastatic Breast Cancer: A Retrospective Real-World Study and an Exploratory Composite Clinical-Inflammatory Risk Score.	Medicina (Kaunas)	2026	https://conductscience.org/library/papers/42654366	PubMed
42,216,212	Real-world data for a CDK4/6 inhibitor, palbociclib, as 1st- or 2nd-line therapy in HR+/HER2- metastatic breast cancer: a multicenter prospective cohort study.	Breast Cancer Res	2026	https://conductscience.org/library/papers/42216212	PubMed
42,139,194	Real world experience with cyclin dependent kinase inhibitors in metastatic breast cancer in India.	PLoS One	2026	https://conductscience.org/library/papers/42139194	PubMed
42,029,173	Maximizing the impact of real-world evidence on cancer treatment: what do we need to achieve it?	J Comp Eff Res	2026	https://conductscience.org/library/papers/42029173	PubMed
42,017,805	Impact of Comorbidities on Clinical Outcomes and Quality of Life of Patients With Hormone Receptor-Positive/Human Epidermal Growth Factor Receptor 2-Negative (HR+/HER2-) Advanced Breast Cancer Treated With Palbociclib in the POLARIS Study.	Cancer Med	2026	https://conductscience.org/library/papers/42017805	PubMed
41,830,752	Real-world effectiveness of palbociclib in combination with an aromatase inhibitor in HR+/HER2- bone-only metastatic breast cancer.	Breast	2026	https://conductscience.org/library/papers/41830752	PubMed

1 to 10 of 86

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Genes3

The genes the Gene search release ties to the paper: Swiss-Prot's references first, then PubTator's text mining.

Gene	NCBI Gene ID	Linked by	In Genes	Source
ERBB2	2,064	PubTator's text mining	https://conductscience.org/library/genes/2064	NCBI Gene
MAT1A	4,143	PubTator's text mining	https://conductscience.org/library/genes/4143	NCBI Gene
NR4A1	3,164	PubTator's text mining	https://conductscience.org/library/genes/3164	NCBI Gene

Drugs2

The drugs whose trials, in the Pipelines release, list the paper.

Drug	ChEMBL ID	The trials list it as	Trials	In Drugs and targets	Source
LETROZOLE	CHEMBL1444	Derived from the trial	1	https://conductscience.org/library/drugs/CHEMBL1444	ChEMBL
PALBOCICLIB	CHEMBL189963	Derived from the trial	1	https://conductscience.org/library/drugs/CHEMBL189963	ChEMBL

Data0

The data bank entries PubMed's record names. Trial numbers are under Trials.

None in this release.

Data dates

The date of each source this release read.

PubMed: 2026-11-06; PubMed
iCite: 2026-11-05; iCite
PMC's ID file: 2026-11-05; PMC's ID file
NIH RePORTER's grant and paper links: 2026-11-01; NIH RePORTER's grant and paper links
Trials: 2026-11-12
Gene search: 2026-11-11
Pipelines: 2026-09-18

Sources 11

ChEMBL, through Open TargetsCC BY-SA 3.0
ClinicalTrials.govNo license stated
HGNCCC0
iCiteCC BY 4.0
NCBI GenePublic domain (US government)
NIH RePORTER's grant and paper linksPublic domain
Open TargetsCC0 1.0
PMC's ID filePublic domain (US government)
PubMedNLM's terms
PubTator 3Public domain
UniProtCC BY 4.0

Each source's terms

ChEMBL, through Open TargetsCC BY-SA 3.0, for the parts from ChEMBL. Read on 8 Nov 2026 at https://platform-docs.opentargets.org/licence
ClinicalTrials.govnone stated
HGNCCC0: https://www.genenames.org/about/license/
iCiteCC BY 4.0
NCBI GeneNone named for the file. NCBI says information created by or for the US government on its site is in the public domain, and asks that NLM be acknowledged: https://www.ncbi.nlm.nih.gov/home/about/policies/
NIH RePORTER's grant and paper linksPublic domain (NIH RePORTER)
Open TargetsCC0 1.0. Open Targets asks that users cite its latest paper: Buniello et al. 2025, Open Targets Platform: facilitating therapeutic hypotheses building in drug discovery, Nucleic Acids Research 53(D1):D1467, PMID 39657122. Read on 8 Nov 2026 at https://platform-docs.opentargets.org/licence
PMC's ID fileNone named for the file. NCBI says information created by or for the US government on its site is in the public domain, and asks that NLM be acknowledged: https://www.ncbi.nlm.nih.gov/home/about/policies/
PubMedNLM's terms
PubTator 3Public domain
UniProtCC BY 4.0. UniProt's licence file: "All databases and documents in the UniProt FTP directory may be copied and redistributed freely, without advance permission, provided that this copyright statement is reproduced with each copy." UniProt asks that users cite its latest paper: The UniProt Consortium, UniProt: the Universal Protein Knowledgebase in 2025, Nucleic Acids Research 53:D609-D617, https://doi.org/10.1093/nar/gkae1010. Read on 9 Nov 2026 at https://www.uniprot.org/help/license

ClinicalTrials.gov's data carry an international copyright outside the United States: https://clinicaltrials.gov/about-site/terms-conditions.

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