Regimen naming conventions (nomenclature)

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=Introduction=
As if the treatment of hematologic and oncologic conditions isn't complicated enough, an added layer of complexity comes in the naming of regimens. Regimen naming conventions have evolved in an ad-hoc manner over many decades. Unlike drug names, gene names, etc. there has been no guiding nomenclature for regimens, leading to a confusing state that vastly increases the complexity of understanding treatment exposures at-scale, for example from disparate electronic health record (EHR) systems.
In 2020, we developed guidelines towards standardizing chemotherapy regimen nomenclature. Since that time, some of the concepts have evolved and some have remained stable. This page is meant to capture the current state of nomenclature guidance. Most but not all content of HemOnc.org follows this guidance. While the 2020 JCO Clinical Cancer Informatics article is freely available, copyright belongs to the American Society of Clinical Oncology. Therefore, portions of the following that are directly from the article are enclosed in quotes. The content on this page was last reviewed and updated in January 2025.
=Regimens Composed of a Single Component=
"These shall be expressed by the generic drug name followed by the suffix “monotherapy.” Alternatively, they can be expressed by the prefix “single-agent” followed by the component name. The suffix “monotherapy” is preferred, unless referring to a category (eg, “single-agent chemotherapy”)." If the component is a compound entity, it should still be referred to as monotherapy; referring to the compound entity by its code name (e.g., S-1) may help to decrease confusion.
===Examples===
*Axicabtagene ciloleucel monotherapy
*Doxorubicin monotherapy
*S-1 monotherapy
*Trifluridine and tipiracil monotherapy
=Regimens Comprising Two Components=
"When the two components are of the same drug category, these shall be expressed in alphabetical order of the generic name, separated by “and” or an ampersand (“&”). When one of the components is a cytotoxic and the other is a monoclonal antibody, a steroid, or radiation, the cytotoxic shall be expressed first." It is allowable to abbreviate radiation as "RT". "For each component, only the first word is capitalized." If there is a commonly used acronym for the regimen, it shall be enclosed in parentheses after the names.
===Examples===
*Carboplatin & Paclitaxel (CP)
*Cisplatin & RT
*Docetaxel & Bevacizumab
*Lenalidomide & Dexamethasone (Rd)
=Regimens Comprising Three or More Components=
==Full Component Names Used==
Components shall be separated by a comma, without the use of “and” (eg, “A, B, C, D” not “A, B, C, and D”). Components shall be listed alphabetically within subcategory, as follows: cytotoxics/targeted therapies first, then monoclonal antibodies, then steroids.
==Abbreviation/Acronym Used for the Entire Regimen==
"In many cases, a philosophical disagreement exists over whether abbreviating a regimen is necessary or advisable for a particular regimen. Exchanging more-precise for less-precise terminology always introduces potential ambiguity. There is no a priori way to adjudicate this issue, as the specifics of individual regimens are important. However, shortening the names of regimens potentially reduces documentation burden for clinicians and registrars, especially when regimens contain more than three drugs or involve alternating combinations of chemotherapy. Regimens should therefore be abbreviated in some form when it is possible to do so in a way that clearly conveys the treatment protocol being used for a particular patient." For regimens with a monoclonal antibody (mAb) component, we recommend the format mAb-backbone, where the mAb is abbreviated as a single letter or the first 3-4 letters. 
===Examples===
*ABVD
*Dara-Kd
*FOLFIRI
*R-CHOP
==Regimens Built on an Existing Two-Drug Backbone==
If there is no widely accepted acronym for the entire regimen, and there is a widely accepted acronym for the backbone, the backbone should be named following the guidelines above. The backbone should be listed first, followed by the additional component(s). If there is only one additional component, it should be added with the "&"; if there are two or more additional components, they should be comma-separated. If there is no widely accepted acronym for the backbone, the drugs should be listed in a comma-separated format, following the ordering described elsewhere on this page (e.g., monoclonal antibodies should be listed last).
===Examples===
*Carboplatin & Paclitaxel (CP) & Bevacizumab
*Cisplatin & Fluorouracil (CF) & RT
*Carboplatin & Paclitaxel (CP), Bevacizumab, Nivolumab
*Carboplatin, nab-Paclitaxel, Atezolizumab (no widely accepted acronym for the platinum doublet carboplatin & nab-paclitaxel)
==Regimens Built on an Existing Three or More-Drug Backbone==
If there is no widely accepted acronym for the entire regimen, and there is a widely accepted acronym for the backbone, the backbone should be listed first, followed by the additional component. For regimens with a monoclonal antibody (mAb) component, we recommend the format mAb-backbone, where the mAb is abbreviated as a single letter or the first 3-4 letters.
===Examples===
*FOLFIRI & Bevacizumab
=Regimens That Are Modifications of Existing Regimens=
Two common modifications are changes to intensity and changes to density. For example, using a higher dose of drugs, giving the drugs more often, or both. By default, the dosing schema that was introduced first is considered the "standard" regimen; for example, R-CHOP is the preferred term, not "R-CHOP-21" or "standard-dose R-CHOP". There is some debate as to the dividing line between a regimen "variant" and a completely separate regimen. We recommend the use of prefixes to denote significant changes in dose density and/or dose intensity. (Note: This portion of the nomenclature is still in evolution.)
==Dose Intensity==
Prefix 	Description 	Examples 	Notes
Low-dose 	Dosing of one or more components is at least 50% lower than standard dosing 	1. Low-dose Cytarabine monotherapy (LoDAC)2. Low-dose R-CHOP	Sometimes called "mini" dosing (e.g., R-miniCHOP)
Intermediate-dose	Dosing that is intermediate between low and high, but not necessarily "standard" 	Intermediate-dose Cytarabine monotherapy (IDAC) 	Not common
Standard-dose 	Dosing that is considered the standard 	R-CHOP 	Label of "Standard-dose" is almost always unnecessary
Escalated-dose 	Dosing of one or more components is at least 50% higher than standard dosing 	Escalated-dose BEACOPP 	Interchangeable with "High-dose"
High-dose 	Dosing of one or more components is at least 50% higher than standard dosing 	High-dose Cytarabine monotherapy (HiDAC) 	Interchangeable with "Escalated-dose"
Ablative-dose 	Dosing that is high enough to cause irreversible stem-cell ablation, requiring either autologous or allogeneic stem cell rescue	1. BEAM2. Ablative-dose Melphalan monotherapy 	Many of these regimens are by definition ablative and do not need the prefix (e.g., BEAM)
Modified-dose (m)	Dosing that is different than "standard" but not appreciably so 	mFOLFOX6 	Due to widespread use of a lower-case "m" appended to the regimen, we will continue to use this convention.
==Dose Density==
Prefix 	Description 	Examples 	Notes
Dose-dense	Dosing generally remains the same but cycles are compressed	1. Dose-dense Cyclophosphamide & Doxorubicin (ddAC)2. Dose-dense AC-T	Usually necessitates growth factor support (G-CSF)
=Regimens with Substitutions=
It is not unusual for regimens to be materially similar except for a single component. Examples include the substitution of predisolone for prednisone in R-CHOP-like regimens, the substitution of subcutaneous (SC) rituximab and hyaluronidase for intravenous (IV) rituximab, or the substitution of a biosimilar. We treat such substitutions as distinct regimens, with the same name as the "standard" regimen plus the substituted component in parentheses. Note that most biosimilar substitutions have not been explicitly studied and are thus considered "synthetic regimens" and are available in the ontology but not necessarily on the website.
===Examples===
*mFOLFOX6 (L-Leucovorin)
*R-CHOP (Prednisolone)
*R-CHOP (SC Rituximab)
*R-CHOP (rituximab-abbs)
*Rituximab-abbs monotherapy
==Frequent substitutions==
Standard component 	Substituted component
Leucovorin (Folinic acid)	Levoleucovorin (L-Leucovorin)
Prednisone 	Prednisolone
Rituximab 	Rituximab and hyaluronidase
Trastuzumab 	Trastuzumab and hyaluronidase
=Regimen Acronyms with Ambiguous Terms=
Unfortunately, many regimens are known primarily by their acronym, but the acronym can refer to more than one regimen. We try to avoid these situations in the primary regimen naming whenever possible, but it is not always possible. In these cases, the distinguishing component is referred to in parentheses.
==Frequent ambiguities==
Drug 1 	Drug 2 	Examples
Epirubicin 	Etoposide 	R-CEOP (Epirubicin) R-CEOP (Etoposide)
Taxol (Paclitaxel)	Taxotere (Docetaxel)	TCHP (Paclitaxel) TCHP (Docetaxel)
=Regimens Comprising Two or More Alternating Sets of Components=
"These regimens consist of subsets of regimens that cannot be inextricably unlinked because of the alternation schedule (eg, A is followed by B, then A, then B, then A, then B). In these cases, when the subsets are acronyms, individual subsets should be separated by a “/”. The “/” indicator shall be reserved for this purpose only; using it elsewhere creates ambiguity as to whether the drugs separated by “/” are given sequentially or together. If the subsets are full names, the separator should be “alternating with.”"
===Examples===
*Capecitabine/Capecitabine & RT
*R-HyperCVAD/R-MA
=Regimens With Eponymous or Idiosyncratic Names=
"Although generally to be avoided, some regimens and protocols are very well established by the name of an individual or a group study. In these cases, if there is a readily understood noneponymous regimen name it should be used, with the eponym parenthetically immediately after the regimen name. If no such nomenclature readily exists, it should be indicated as a regimen, either by inclusion of the word “regimen” or with alternate modifiers clarifying the preceding acronym."
This type of naming convention is especially common in pediatric hematology/oncology, where protocols can be quite long and complex. In the case where a protocol has more than one arm based on risk-stratification, this should be clearly indicated in the protocol name.
===Examples===
*AALL0232 consolidation
*CALGB 10-002 regimen
*COG AALL0932 protocol, standard-risk arm
*Roswell Park regimen
*SIOPEL-4 protocol
=Variant Naming=
"Many widely used regimens are variants of other regimens, involving the same drugs on an alternate dose level or schedule that does not easily fit into the modification paradigm as explained above. Sometimes these variants exist to avoid toxicity in the context of antecedent organ dysfunction or to treat patients who were too frail to be studied in initial trials. If such variants are indicated by widely accepted modifiers, these should be used, as they can avoid significant complexity in regimen naming while conveying the same meaning. If not, the modification to the existing regimen should be indicated as succinctly as possible, with the modified drug indicated in the same fashion as in the initial regimen."
===Examples===
*Capecitabine monotherapy 2500 mg/m2/day
*Cisplatin & Gemcitabine (GC) 75/1200 x 4
*Cisplatin & Gemcitabine (GC) 75/1250 x 3
=Protocols Comprising Two or More Regimens=
"These are often complex treatments that consist of two or more sequential procedures or regimens assembled into a total protocol. Each temporally distinct regimen or procedure should be separated by “, then.” There are some exceptions to this; for example, some widely used sequential breast cancer regimens involve a sequence of an anthracycline/cyclophosphamide doublet and a taxane, and the temporal separation between regimens is represented by a dash (eg, AC-T). Unless such representations are common, they should be avoided."
===Examples===
*Surgery, then AT (Taxol) x 4, then CMF x 4
*Temozolomide & RT, then Temozolomide
*TH (Paclitaxel) x 12 wk, then FEC & H x 4, then surgery
Category:General reference pages