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The Voice of People With Breast Cancer


Our Voices Blog

Understanding Common Research Terms

Have you ever found yourself confused and wondering what all those scientific terms mean in the research studies we share on breast cancer? If so, we’ve compiled a list of common terms used in various breast cancer news articles to help explain how they are used in determining the results and progress of clinical trials and research.

Adjuvant: Breast cancer treatment or therapy than happens after breast surgery is performed to remove a tumor.[i]

Adverse events: These are any side effects or complications that occur while undergoing treatment and are considered to be a result of that treatment.[ii]

Basket trials: A clinical trial in which the efficacy and/or effectiveness of a treatment is tested among patients with different cancers that have the same mutation or biomarker.[iii]

Clinical trials: A research study in which a new therapy, treatment, or procedure is tested against the standard of care.[iv]

Disease-free survival: The length of time between when primary treatment ends to signs of recurrence.

Double-blind study: Most studies divide participants into at least two groups in which one group receives the treatment being tested and the other group receives the standard of care. A double-blind study is a study design where neither the individual receiving treatment nor the individual administering the treatment is aware of which group the participant has been assigned to.[v]

Efficacy and effectiveness: Both terms refer to how the treatment is performing. Efficacy focuses on performance in ideal conditions while effectiveness refers to performance in a real-world setting.[vi]

Event-free survival: The length of time between the end of primary treatment to the first signs of a new “event.”[vii],[viii] This is different from disease-free survival because it focuses on any new event or complication that occurs.[ix]

Lines of therapy: Describes the order that a patient receives treatment for their disease as it progresses.[x]

Neoadjuvant: Refers to therapies or treatments for breast cancer that is given to shrink the tumor and thar occurs prior to breast cancer surgery.[xi]

Overall survival: This refers to the time between diagnosis or the start of treatment to the time of death.[xii]

Pathologic complete response: There is no evidence in any biopsy or tissue sample taken from the body that cancer is present following treatment.[xiii]

Progression-free survival: This term refers to the time that a patient lives with their disease and it does not progress or continue to grow, also known as stable disease. This term is often used when reporting findings in studies focusing on metastatic breast cancer as the patient is not cured of cancer but instead continues to live without it advancing.[xiv]

[i] What is adjuvant therapy for breast cancer? from MD Anderson Cancer Center

[ii] Adverse event from National Cancer Institute

[iii] Basket trial from National Cancer Institute

[iv] Clinical Trials Series Part 1 from Canadian Breast Cancer Network

[v] David S., Khandhar P.B. (2021). Double-Blind Study. StatPearls [Internet].

[vi] Singal, A.G. (2014). A Primer on Effectiveness and Efficacy Trials. Clinical and Translational Gastroenterology 5(1)

[vii] Event-free survival from National Cancer Institute

[viii] Event-free survival from

[ix] What do clinical trial results mean? from Cancer Research UK

[x] What Are “Lines of Therapy”? from Metastatic Trial Talk

[xi] What is adjuvant therapy for breast cancer? from MD Anderson Cancer Center

[xii] Overall survival from National Cancer Institute

[xiii] Pathologic complete response from National Cancer Institute

[xiv] Progression-free survival from National Cancer Institute

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