Bile ducts

Basket study

Source: [4].

«Basket trials (or studies) test the effect of one drug on a single mutation in a variety of tumor types [baskets], at the same time. These studies also have the potential to greatly increase the number of patients who are eligible to receive certain drugs relative to other trials designs [1], «allowing researchers to analyze each cancer type individually, as well as assess the impact of the drug or drug combinations as a whole. Using this approach, it is possible to combine what would have been multiple phase 2 trials into a single study [4]». «In the evaluation of targeted therapies, basket trials have emerged as an approach to test the hypothesis that targeted therapies may be effective independent of tumor histology, as long as the molecular target is present [2].» «Most basket trials typically aim to answer multiple questions simultaneously [3].»

Bibliographic references:
[1] Clinical Trial Design and Methodology. ASCO. https://www.asco.org/research-progress/clinical-trials/clinical-trial-resources/clinical-trial-design-and-methodology. Accessed August 18, 2018.

[2] Redig AJ, Jänne PA. Basket trials and the evolution of clinical trial design in an era of genomic medicine. J Clin Oncol. 2015 Mar 20;33(9):975-7. Available at: https://doi.org/10.1200/JCO.2014.59.8433.

[3] Cunanan KM, Gonen M, Shen R, et al. Basket Trials in Oncology: A Trade-Off Between Complexity and Efficiency. J Clin Oncol. 2017 Jan 20;35(3):271-273. Available at: https://doi.org/10.1200/JCO.2016.69.9751.

[4] Illuminating ideas: Innovative clinical trial design. Roche.com. https://www.roche.com/research_and_development/who_we_are_how_we_work/clinical_trials/innovative-clinical-trial-design.htm. Accessed August 18, 2018.

Bystander effects

«Bystander effects describe the ability of an irradiated cell to send a signal capable of eliciting a response in a nonirradiated cell. This signal may be communicated via cell-to-cell gap junction communication and/or from secreted or shed factors from irradiated cells [1].»

Bibliographic references:

[1] Varnum SM, Sowa MB, and Morgan WF. (2013). B. In: L. Brady and T. Yaeger, ed., Encyclopedia of Radiation Oncology, 1st ed. Springer-Verlag Berlin Heidelberg, pp.75.

Biochemical failure in prostate cancer

«The definition of biochemical recurrence following radiation therapy is complicated by the incomplete ablation of all functioning prostatic epithelium, which creates difficulty in establishing a meaningful absolute nadir and the phenomenon of “prostate-specific antigen (PSA) bounce”» [4]. Biochemical failure after primary radiotherapy with or without hormonal therapy in men with clinically localized prostate cancer by 2005 RTOG-ASTRO Phoenix Consensus Conference is: 1) PSA rise by 2 ng/mL or more above the nadir PSA; and 2) a recurrence evaluation should be considered when PSA has been confirmed to be increasing after radiation even if the rise above nadir is not yet 2 ng/mL, especially in candidates for salvage local therapy who are young and healthy [1]. The rise has to be at least 25% over nadir [5]. «This definition accepts some limitation on sensitivity in the interest of increased specificity for detecting failures associated with clinical outcomes other than cure» [4].
Following radical prostatectomy, a cutoff of 0.2 ng/mL has been associated with a high likelihood of subsequent PSA progression [2]. More recently, 0.4 ng/mL and rising has been proposed as a definition associated more closely with the development of distant metastases [3]. However, according to the ASTRO/AUA (American Urological Association) guidelines [6], «biochemical (PSA) recurrence after surgery is defined as detection of PSA concentration at 0.2 ng/mL, with a second confirmatory level detected at 0.2 ng/mL.»
Following salvage radiotherapy, biochemical recurrence is «defined as a rise in PSA ≥ 0.2 ng/ml above the PSA nadir followed by a sequentially equal or higher value [7].»

Bibliographic references:

[1] Roach M 3rd, Hanks G, Thames H Jr, et al. Defining biochemical failure following radiotherapy with or without hormonal therapy in men with clinically localized prostate cancer: recommendations of the RTOG-ASTRO Phoenix Consensus Conference. Int J Radiat Oncol Biol Phys. 2006 Jul 15;65(4):965-74. Available at: https://doi.org/10.1016/j.ijrobp.2006.04.029.
[2] Freedland SJ, Sutter ME, Dorey F, Aronson WJ. Defining the ideal cutpoint for determining PSA recurrence after radical prostatectomy. Prostate-specific antigen. Urology. 2003 Feb;61(2):365-9. Available at: http://dx.doi.org/10.1016/S0090-4295(02)02268-9.
[3] Amling CL, Bergstralh EJ, Blute ML, et al. Defining prostate specific antigen progression after radical prostatectomy: what is the most appropriate cut point? J Urol. 2001 Apr;165(4):1146-51. Available at: http://dx.doi.org/10.1016/S0022-5347(05)66452-X.
[4] Nielsen ME, Partin AW. The Impact of Definitions of Failure on the Interpretation of Biochemical Recurrence Following Treatment of Clinically Localized Prostate Cancer. Rev Urol. 2007 Spring;9(2):57-62.
[5] Lowrance WT, Roth BJ, Kirkby E, Murad MH, Cookson MS. Castration-Resistant Prostate Cancer: AUA Guideline Amendment 2015. J Urol. 2016 May;195(5):1444-52. Available at: https://doi.org/10.1016/j.juro.2015.10.086.
[6] Valicenti RK, Thompson I Jr, Albertsen P, et al. Adjuvant and salvage radiation therapy after prostatectomy: American Society for Radiation Oncology/American Urological Association guidelines. Int J Radiat Oncol Biol Phys. 2013 Aug 1;86(5):822-8. Available at: https://doi.org/10.1016/j.ijrobp.2013.05.029.
[7] Jackson WC, Suresh K, Tumati V, et al. Impact of Biochemical Failure After Salvage Radiation Therapy on Prostate Cancer-specific Mortality: Competition Between Age and Time to Biochemical Failure. Eur Urol Oncol. 2018 Sep;1(4):276-282. Available at: https://doi.org/10.1016/j.euo.2018.04.014. 

Boolean search

«A type of search allowing users to combine keywords with operators such as AND, NOT and OR to further produce more relevant results. For example, a Boolean search could be "hotel" AND "New York". This would limit the search results to only those documents containing the two keywords [1].» «Boolean searches allow you to combine words and phrases using the words AND, OR, NOT and NEAR (otherwise known as Boolean operators) to limit, widen, or define your search [2].»

In: Awesome Daily Staff. StumbleUpon. Stumbleuponcom. 2014. Available at: http://www.stumbleupon.com/su/2XigqH. Accessed February 25, 2017.

In: Wallace I. 9 Useful Browser Shorcuts. Stumbleuponcom. 2014. Available at: http://www.stumbleupon.com/su/30Xbyy/:G5nkn8+p:jlRVwzM!/infographicjournal.com/9-useful-browser-shorcuts. Accessed March 21, 2017.

Bibliographic references:

[1] Webopedia.com. (2016). What is Boolean Search? Webopedia Definition. [online] Available at: http://www.webopedia.com/TERM/B/Boolean_search.html [Accessed 31 Oct. 2016].

[2] Lifewire. (n.d.). What is a Boolean Search?. [online] Available at: https://www.lifewire.com/what-does-boolean-search-3481475 [Accessed 31 Oct. 2016].

Bolus

It is a mass of scattering material, such as wax or paraffin, placed between the radiation source and the skin to achieve a precalculated isodose pattern in the tissue irradiated. It is a quantity of tissue-equivalent material placed in the radiation beam, over the surface of the irradiated region, to fill in irregular body surfaces, to improve dose distribution (homogenize or modulate the range of the dose from external beams of radiation [1]) and to increase the absorbed dose in the superficial tissues (increase the dose to the skin) [2]. It is a material of density nearly equivalent to tissue placed within the treatment beam to compensate for unevenness of body contour or to enhance the buildup of electrons on the surface of the skin [3]. It will reduce the penetration depth of the radiation beam, bringing it closer to the surface of the patient's skin [4]. It can be used for megavoltage (high energy) photon and electron radiation therapy. Materials used as bolus vary from simple water to metal and include various mixtures and compounds [5].

Bibliographic references:

[1] Wikipedia. (2016). Bolus (medicine). [online] Available at: https://en.wikipedia.org/wiki/Bolus_(medicine)  [Accessed 26 May 2016].

[2] TheFreeDictionary.com. (2016). bolus. [online] Available at: http://medical-dictionary.thefreedictionary.com/bolus [Accessed 26 May 2016].

[3] Kentuckyonehealth.org. (2016). Radiation Therapy Glossary Lexington, Kentucky (KY) - Saint Joseph Hospital. [online] Available at: http://www.kentuckyonehealth.org/hospital-cancer-center-radiation-oncology-therapy-glossary [Accessed 26 May 2016].

[4] Perelman School of Medicine, University of Pennsylvania, Department of Radiation Oncology. (n.d.). Glossary of Terms for Radiation Oncology. [online] Available at: http://www.xrt.upenn.edu/documents/RadOncGlossaryofTerms.pdf [Accessed 26 May 2016].

[5] Vyas V, Palmer L, Mudge R, Et al. On bolus for megavoltage photon and electron radiation therapy. Med Dosim. 2013 Autumn;38(3):268-73. Available at: http://dx.doi.org/10.1016/j.meddos.2013.02.007.

BED (biologically effective dose)

"In fracionated radiotherapy, the total dose that would be required in very small dose fractions to produce a particular effect" [1]. It is proportional to log cell kill, and it's more conceptually useful as a measure of biological damage than a physical dose, the effects of which vary with fraction size and dose rate. Formally, it is the radiation dose equivalent to an infinite number of infinitely small fractions or a very low dose-rate. It corresponds to the intrinsic radiosensitivity (α) of the target cells when all repairable radiation damage (β) has been given time to be repaired. In linear quadratic modeling, BED=total dose x relative effectiveness (RE), where RE=(1+d/α/β), with d=dose per fraction [2]. "Otherwise known as extrapolated total dose (ETD). BED values calculated from different α/β ratios are not directly comparable. For time-dose calculations, EQD2 is preferred" [1].

Bibliographic references:

[1] Joiner, M. and van der Kogel, A. ed., (2009). Glossary of terms in radiation biology. In: Basic Clinical Radiobiology, 4th ed. London, United Kingdom: Hodder Arnold, an Hachette UK Company, p.353.

[2] Fowler, J. (2006). Part I: Basic Concepts in Treatment Planning, 1. Practical Time-Dose Evaluations, or How to Stop Worrying and Learn to Love Linear Quadratics. In: S. Levitt, J. Purdy, C. Perez and S. Vijayakumar, ed., Technical Basis of Radiation Therapy, Practical Clinical Applications, 4th ed. Springer-Verlag Berlin Heidelberg, pp.3-31.

β, beta

Repair capacity. Loge of the number of cells sterilized in a repairable way per gray squared.
Bibliographic reference: Fowler, J. (2006). Part I: Basic Concepts in Treatment Planning, 1. Practical Time-Dose Evaluations, or How to Stop Worrying and Learn to Love Linear Quadratics. In: S. Levitt, J. Purdy, C. Perez and S. Vijayakumar, ed., Technical Basis of Radiation Therapy, Practical Clinical Applications, 4th ed. Springer-Verlag Berlin Heidelberg, pp.3-31.