Missing data or missing values

In statistics, they «occur when no data value is stored for the variable in an observation [1].» They are «values of variables within data sets which are not known [2].»

Bibliographic references:

[1] Missing data [Internet]. En.wikipedia.org. 2016 [cited 19 November 2016]. Available from: https://en.wikipedia.org/wiki/Missing_data.

[2] Statistics Glossary: M [Internet]. Statsoft.com. 2016 [cited 19 November 2016]. Available from: http://www.statsoft.com/textbook/statistics-glossary/m#Missing values.

Standard error (SE)

«These are the SEs for the descriptive statistics. The SE gives some idea about the variability possible in the statistic [1].» It «(...) is a measure of the variability of a statistic. It is an estimate of the standard deviation of a sampling distribution [2].» It «(...) is the standard deviation of the sampling distribution of a statistic, (...) (Everitt BS, 2003, cited in [3]). «The SE of the mean [SEM] (...) is the theoretical standard deviation of all sample means of size n drawn from a population and depends on both the population variance (sigma) and the sample size (n) (...) [4].» «The SEM can be seen to depict the relationship between the dispersion of individual observations around the population mean (the standard deviation), and the dispersion of sample means around the population mean (the SE). Different samples drawn from that same population would in general have different values of the sample mean, so there is a distribution of sampled means (with its own mean and variance). (...) As the sample size increases, the dispersion of the sample means clusters more closely around the population mean and the SE decreases [3].» «The SE depends on three factors: the number of observations in the population (N), the number of observations in the sample (n), and the way that the random sample is chosen. If the population size is much larger than the sample size, then the sampling distribution has roughly the same SE, whether we sample with or without replacement . On the other hand, if the sample represents a significant fraction (say, 1/20) of the population size, the SE will be noticeably smaller, when we sample without replacement [2].» «The SE of the proportion (...) is the standard deviation of the distribution of the sample proportion over repeated samples [4].»

Source: Steve's Favorites. Pinterest. Available at: https://www.pinterest.pt/pin/419819996504206121/. Accessed November 3, 2017.

Bibliographic references:

[1] Annotated SPSS Output: Descriptive statistics [Internet]. Ats.ucla.edu. 2016 [cited 20 November 2016]. Available from: http://www.ats.ucla.edu/stat/spss/output/descriptives.htm.

[2] Statistics Dictionary [Internet]. Stattrek.com. 2016 [cited 20 November 2016]. Available from: http://stattrek.com/statistics/dictionary.aspx.

[3] Standard error [Internet]. En.wikipedia.org. 2016 [cited 20 November 2016]. Available from: https://en.wikipedia.org/wiki/Standard_error#cite_note-1.

[4] Statistics Glossary: S [Internet]. Statsoft.com. 2016 [cited 20 November 2016]. Available from: http://www.statsoft.com/textbook/statistics-glossary/s#Standard.

Confidence interval (CI)

It is «a range of values, calculated from the sample observations, that is believed, with a particular probability, to contain the true parameter value» [1]. It is used «to express the degree of uncertainty associated with a sample statistic. A confidence interval is an interval estimate combined with a probability statement.» One «might describe the interval estimate as a "95% confidence interval". This means that if» one «used the same sampling method to select different samples and computed an interval estimate for each sample,» one «would expect the true population parameter to fall within the interval estimates 95% of the time» [2]. «Precision is taken to be the narrowness of the confidence interval. (...) The interval estimate is an expression of the uncertainty surrounding the point estimate and derives mainly from sampling variation as well as measurement variation/error. In general, the degree of uncertainty is inversely related to the size of the study. On one hand, if a study is too small, the uncertainty may increase to a level considered to be undesirable or useless. On the other, as the study size increases, the degree of uncertainty decreases, and the interval estimate becomes narrower» [3]. «Confidence intervals are preferred to point estimates and to interval estimates, because only confidence intervals indicate the precision of the estimate and the uncertainty of the estimate» [2].

Bibliographic references:

[1] Everitt, B. and Skrondal, A. (2010). The Cambridge dictionary of statistics. 4th ed. Cambridge, UK: Cambridge University Press.

[2] Stattrek.com. (2016). Statistics Dictionary. [online] Available at: http://stattrek.com/statistics/dictionary.aspx [Accessed 13 Nov. 2016].

[3] Broeck, J. and Brestoff, J. (2013). Epidemiology: Principles and Practical Guidelines. 1st ed. Dordrecht: Springer.

Standard deviation (σ or s)

«The standard deviation of a population is denoted by σ and the standard deviation of a sample, by s [1].» It is a measure of dispersion or absolute variability [2,3] in original units (unit of measurement equal to that of the mean). It is the positive square root of the variance (σ² or s² or Var[X]). It «is useful as a measure of variation within a given set of data» [4]. «A small value of the standard deviation indicates that most values are close to the sample mean. A large value of the standard deviation indicates many values are far from the sample mean. Other words which are used to convey the concept of the standard deviation are “spread” and “scale.”» It is «the “typical” spread of observations about the sample mean [2].» It «is a numerical value used to indicate how widely individuals in a group vary. If individual observations vary greatly from the group mean, the standard deviation is big; and vice versa [1].»

Bibliographic references:
[1] Stattrek.com. (2016). Statistics Dictionary. [online] Available at: http://stattrek.com/statistics/dictionary.aspx [Accessed 13 Nov. 2016].
[2] Supino, P. and Borer, J. (2012). Principles of research methodology. 1st ed. New York, NY: Springer.
[3] Doi, S. and Williams, G. (2013). Methods of clinical epidemiology. 1st ed. Berlin: Springer.

[4] Daniel, W. and Cross, C. (2013). Biostatistics: a foundation for analysis in the health sciences. 10th ed. Danvers, Massachusetts, USA: John Wiley & Sons, Inc.

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].

Vx

Vx is the percent volume of the organ or target receiving ≥x Gy [1,3], or the volume covered by the isodose of x% [2].

Bibliographic references:
[1] Lu JY, Lin Z, Zheng J, et al. Dosimetric evaluation of a simple planning method for improving intensity-modulated radiotherapy for stage III lung cancer. Sci Rep. 2016 Mar 24;6:23543. Available at: https://dx.doi.org/10.1038/srep23543.
[2] Zhang T, Liang ZW, Han J, et al. Double-arc volumetric modulated therapy improves dose distribution compared to static gantry IMRT and 3D conformal radiotherapy for adjuvant therapy of gastric cancer. Radiat Oncol. 2015 May 19;10:114. Available at: https://dx.doi.org/10.1186/s13014-015-0420-x.

[3] Huang EX, Bradley JD, El Naqa I, et al. Modeling the risk of radiation-induced acute esophagitis for combined Washington University and RTOG trial 93-11 lung cancer patients. Int J Radiat Oncol Biol Phys. 2012 Apr 1;82(5):1674-9. Available at: https://dx.doi.org/10.1016%2Fj.ijrobp.2011.02.052.

MATHEWS OPEN ACCESS JOURNALS: Reirradiation of Skin Tumors

MATHEWS OPEN ACCESS JOURNALS: Reirradiation of Skin Tumors:                                                         www.mathewsopenaccess.com             http://www.mathewsopenaccess.com/PDF/Ca...

Tpot (potential doubling time without cell loss)

It describes the proliferation rate of the tissues, which can be measured from biopsies by flow cytometry after administration in situ to the patient of a deoxyribonucleic acid thymidine tracer [2]. "This is difficult to determine in vivo." It is "the time which the cell population of tumor doubles if there is no cell loss" [3]. Tp (potential doubling time or cell doubling time after cell loss) is a little shorter than Tpot (measured before the tumour has received any cytotoxic treatment) [1].

Pretreatment Tpot measured in human tumor biopsies [2].
Tumor	Median (days)	Range (days)
Larynx	4	2-19
Tongue	4-6	2-16
Mouth, cheek	3.4	2-15
Esophagus	5	2.5-20
Cervix	5	3-20
Rectum	5	3-18
Prostate	42	15-70
Breast	14	3-70

Bibliographic references:

[1] Fowler, JF. 21 years of Biologically Effective Dose. Br J Radiol. 2010 Jul; 83(991): 554–568. Available at: http://dx.doi.org/10.1259%2Fbjr%2F31372149.

[2] Fowler JF. The radiobiology of prostate cancer including new aspects of fractionated radiotherapy. Acta Oncol. 2005;44(3):265-76. Available at: http://dx.doi.org/10.1080/02841860410002824.
[3] The timely delivery of radical radiotherapy: standards and guidelines for the management of unscheduled treatment interruptions. (2008). 3rd ed. London, United Kingdom: Board of Faculty of Clinical Oncology, The Royal College of Radiologists. Available at: https://www.rcr.ac.uk/sites/default/files/publication/BFCO(08)6_Interruptions.pdf [Accessed 17 Jul. 2016].

K value or K factor

It is “the BED [biologically effective dose] equivalent of repopulation (in units of Gy/day)”, “the BED-equivalent repopulation factor” [1]. It is the "increase in dose required daily to obtain same biologic effect: recommended extra dose to add to total radiation dose for each day of prolongation, which can be given by increasing daily dose of remaining treatment". "Prolongation of overall treatment time due to unplanned interruptions during radiotherapy causes deleterious effect of accelerated repopulation of tumor clonogens. For the cancers of the head and neck, even a 1-day interruption resulted in a decrease in the local control rate by 1.4%" [9]. A “K value of 0.9 Gy/day represents the BED required each day (after Tdelay has been passed) to offset repopulation” [2]. It is “the biological dose per day required to compensate for on-going tumour cell repopulation. K is the BED equivalent of 1 days’ worth of repopulation” [3], “a factor used to determine the amount of radiation ‘wasted’ due to ongoing tumour repopulation” [4]. “If chemotherapy is able to completely inhibit repopulation then K=0 and would not be required” [1].
For head and neck treatments, it is “recommend K=0.1 Gy/day and Tdelay=0 in cases where the final overall times are less than 28 days” [1]. However, after this time, the K value is 0.5-0.7 Gy/day [9].

“There is at present very little data relating to K and Tdelay factors for other tumour types” [1].
“For cervix tumours, the time factors are probably around half those for head and neck tumours, i.e., 0.5 Gy/day” [1,5]. “For breast tumours, the K factors are likely to be around 0.3 Gy/day while for prostate tumours they are likely to be in the region 0.1–0.3 Gy/day, or even lower [1,6-8]”. “Little is known about the corresponding values of Tdelay” [1]. For transitional cell bladder carcinoma, K=0.36 Gy/day for a Tdelay=5-6 weeks [9]. For non-small cell lung cancer and a Tdaley>20 days, K=0.45 Gy/day [10,11]; but, for cases without mediastinal involvement, K=0.2 Gy/day [10].

Bibliographic references:

[1] Stamatakos, G. (2012). 2012 5th International Advanced Research Workshop on In Silico Oncology and Cancer Investigation (IARWISOCI). Piscataway, NJ: IEEE. Available at: http://www.5th-iarwisoci.iccs.ntua.gr/data/_uploaded/file/PROCEEDINGS_2012_5th_IARWISOCI_OPEN-ACCESS_VERSION_2012_DEC_05.pdf [Accessed 19 Jul. 2016].

[2] Dale RG, Hendry JH, Jones B, et al. Practical methods for compensating for missed treatment days in radiotherapy, with particularreference to head and neck schedules. Clin Oncol (R Coll Radiol). 2002 Oct;14(5):382-93. Available at: http://dx.doi.org/10.1053/clon.2002.0111.

[3] Dale RG, Jones B, Sinclair JA. Dose-equivalents of tumour repopulation during radiotherapy: the potential for confusion. Br J Radiol. 2000;73(872):892–894. Available at: http://dx.doi.org/10.1259/bjr.73.872.11026867.

[4] The timely delivery of radical radiotherapy: standards and guidelines for the management of unscheduled treatment interruptions. (2008). 3rd ed. London, United Kingdom: Board of Faculty of Clinical Oncology, The Royal College of Radiologists. Available at: https://www.rcr.ac.uk/sites/default/files/publication/BFCO(08)6_Interruptions.pdf [Accessed 17 Jul. 2016].

[5] Hendry JH, Bentzen SM, Dale RG, et al. A modelled comparison of the effect of using different ways to compensate for missed treatment days in radiotherapy. Clin Oncol. 1996;8(5):297–307. Available at: http://dx.doi.org/10.1016/s0936-6555(05)80715-0.

[6] Haustermans K, Fowler J, Geboes K, et al. Relationship between potential doubling time (Tpot), labelling index and duration of DNA synthesis in 60 oesophageal and 35 breast tumours: is it worthwhile to measure Tpot? Radiother Oncol. 1998;46(2):157–167. Available at: http://dx.doi.org/10.1016/s0167-8140(97)00164-3.

[7] Trott KR, Kummermehr J. What is known about tumour proliferation rates to choose between accelerated fractionation or hyperfractionation? Radiother Oncol. 1985;3(1):1–9. Available at: http://dx.doi.org/10.1016/s0167-8140(85)80002-5.

[8] King CR. What is the Tpot for prostate cancer? Radiobiological implications of the equivalent outcome with 125I or 103Pd. Int J Radiat Oncol Biol Phys. 2000;47(5):1165–1167. Available at: http://dx.doi.org/10.1016/s0360-3016(00)00543-5.
[9] Bese NS, Hendry J, Jeremic B. Effects of prolongation of overall treatment time due to unplanned interruptions during radiotherapy of different tumor sites and practical methods for compensation. Int J Radiat Oncol Biol Phys. 2007 Jul 1;68(3):654-61. Available at: http://dx.doi.org/10.1016/j.ijrobp.2007.03.010.
[10] Koukourakis M, Hlouverakis G, Kosma L, et al. The impact of overall treatment time on the results of radiotherapy for nonsmall cell lung carcinoma. Int J Radiat Oncol Biol Phys. 1996 Jan 15;34(2):315-22. Available at: http://dx.doi.org/10.1016/0360-3016(95)02102-7.
[11] Chen M, Jiang GL, Fu XL, et al. The impact of overall treatment time on outcomes in radiation therapy for non-small cell lung cancer. Lung Cancer. 2000 Apr;28(1):11-9. Available at: http://dx.doi.org/10.1016/S0169-5002(99)00113-0.

Tp (potential doubling time or cell doubling time after cell loss)

Tp is the potential doubling time of tumors [1]. It is the constant repopulation rate, i.e., a constant cell doubling time up to the end of the radiation treatment [2]. It is is the average doubling time of the clonogenic cells in days [3]. For example, in head and neck tumours or cervix cancer, it can be as short as 2 days; therefore one loses up to 1 Gy worth of cell killing when prolonging the course of radiotherapy. Tp it the fastest time in which a tumour can double its volume and depends on cell type and can be of the order of 2 days in fast growing tumours [1]. This "volume doubling time is determined by cell cycle time, growth factor, and rate of cell loss." Tumours such as squamous cel carcinomas have a relatively short volume doubling time; adenocarcinomas have a longer volume doubling time [4]. It can be measured in cell biology experiments (that requires optimal conditions for the tumour and is a worst case scenario) [1].
Patients on treatment should be prioritised according to the volume doubling time. The prolongation of overall treatment time affects treatment outcome or local tumour control in patients with tumours with short Tp [4].
In patients with muscle-invasive transitional cell bladder carcinoma, the clonogen doubling time is about 5–8 days [5].

Bibliographic references:

[1] IAEA Training Material on Radiation Protection in Radiotherapy - Radiation Protection in Radiotherapy - Part 3 - Biological Effects - Lecture 2: High Doses in Radiation Therapy. (2013). [Lectures/Slides]. Vienna, Austria: International Atomic Energy Agency. Available at: https://rpop.iaea.org/RPOP/RPoP/Content/Documents/TrainingRadiotherapy/Lectures/RT03_RadBiol2_RT_WEB.ppt [Accessed 12 Jul. 2016].

[2] Fowler, JF. 21 years of Biologically Effective Dose. Br J Radiol. 2010 Jul; 83(991): 554–568. Availavle at: http://dx.doi.org/10.1259%2Fbjr%2F31372149.

[3]  Tomé WA, Fowler JF. On the inclusion of proliferation in tumour control probability calculations for inhomogeneously irradiated tumours. Phys Med Biol. 2003 Sep 21;48(18):N261-8. Available at: http://dx.doi.org/10.1088/0031-9155/48/18/402.
[4] The timely delivery of radical radiotherapy: standards and guidelines for the management of unscheduled treatment interruptions. (2008). 3rd ed. London, United Kingdom: Board of Faculty of Clinical Oncology, The Royal College of Radiologists. Available at: https://www.rcr.ac.uk/sites/default/files/publication/BFCO(08)6_Interruptions.pdf [Accessed 17 Jul. 2016].
[5] Bese NS, Hendry J, Jeremic B. Effects of prolongation of overall treatment time due to unplanned interruptions during radiotherapy of different tumor sites and practical methods for compensation. Int J Radiat Oncol Biol Phys. 2007 Jul 1;68(3):654-61. Available at: http://dx.doi.org/10.1016/j.ijrobp.2007.03.010.

Tk (kick-off time or onset time) or Tdelay or Tdel

T_k, T_delay [1], or T_del [2] "represents any delay in the start of tumour cell repopulation in response to radiation treatment after radiation treatment has started." Repopulation of tumour cells due to radiation treatment starts after a passed lag period of T_k treatment days [3]. The repopulation time of tumour cells appears to vary during radiotherapy; at the commencement it may be slow (e.g., due to hypoxia); however, a certain time after the first fraction of radiotherapy (kick-off time), repopulation accelerates [4]. T_k is "the apparent starting time of rapid compensatory repopulation in tumor or tissue after the start of treatment, when it is assumed that there are just two rates of cell proliferation during radiotherapy: zero from start to T_k, then constant doubling each T_p days [cell doubling time] until end of treatment at T days [overall treatment time]" [5].

T_k could be between 21 and 32 days in human head and neck tumors [6,7] and non-small-cell lung cancer, and unlikely may be shorter, but may be longer in prostate cancer [8]. Fowler et al. [9] considered that prostate cancer would have a T_K value up to 10 times the T_K for head and neck tumors, approximately between 210 and 300 days, and Leborgne et al. [10] considered a T_K for prostate cancer of 52 days. Values for adenocarcinoma of the anus have not been defined [11].

Bibliographic references:
[1] The timely delivery of radical radiotherapy: standards and guidelines for the management of unscheduled treatment interruptions. (2008). 3rd ed. London, United Kingdom: Board of Faculty of Clinical Oncology, The Royal College of Radiologists. Available at: https://www.rcr.ac.uk/sites/default/files/publication/BFCO(08)6_Interruptions.pdf [Accessed 17 Jul. 2016].
[2] Wyatt RM, Beddoe AH, Dale RG. The effects of delays in radiotherapy treatment on tumour control. Phys Med Biol. 2003 Jan 21;48(2):139-55. Available at: http://dx.doi.org/10.1088/0031-9155/48/2/301.

[3] Tomé WA, Fowler JF. On the inclusion of proliferation in tumour control probability calculations for inhomogeneously irradiated tumours. Phys Med Biol. 2003 Sep 21;48(18):N261-8. Available at: http://dx.doi.org/10.1088/0031-9155/48/18/402.

[4] IAEA Training Material on Radiation Protection in Radiotherapy - Radiation Protection in Radiotherapy - Part 3 - Biological Effects - Lecture 2: High Doses in Radiation Therapy. (2013). [Lectures/Slides]. Vienna, Austria: International Atomic Energy Agency. Available at: https://rpop.iaea.org/RPOP/RPoP/Content/Documents/TrainingRadiotherapy/Lectures/RT03_RadBiol2_RT_WEB.ppt [Accessed 12 Jul. 2016].

[5] 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.

[6] Brenner, DJ.  Accelerated repopulation during radiotherapy.  Quantitative evidence for delayed onset. Radiat Oncol Invest. 1993;1(3):167–72. Available at: http://dx.doi.org/10.1002/roi.2970010306.

[7] Roberts, SA, Hendry, JH.  Time factors in larynx tumor radiotherapy: lag times and intertumor heterogeneity in clinical datasets from four centers. Int J Radiat Oncol Biol Phys. 1999;45(5):1247–57. Available at: http://dx.doi.org/10.1016/s0360-3016(99)00320-x.
[8] Fowler JF. Development of radiobiology for oncology—a personal view. Phys Med Biol. 2006 Jul 7;51(13):R263-86. Available at: http://dx.doi.org/10.1088/0031-9155/51/13/R16.
[9] Fowler, JF, Ritter, MA, Fenwick , JD, Chappell, RJ. How low is the alpha/beta ratio for prostate cancer? In regard to Wang et al., IJROBP 2003;55:194-203, Int J Radiat Oncol Biol Phys. 2003;57(2):593–5. Available at: http://dx.doi.org/10.1016/s0360-3016(03)00364-x.

[10] Leborgne, F, Fowler, J, Leborgne, JH, Mezzera, J. Later outcomes and alpha/beta estimate from hypofractionated conformal threediomensional radiotherapy versus standard fractionation for localized prostate cancer. Int J Radiat Oncol Biol Phys. 2012;82(3):1200–7. Available at: http://dx.doi.org/10.1016/j.ijrobp.2010.12.040.
[11] Joon DL, Chao MW, Ngan SY, Joon ML, Guiney MJ. Primary adenocarcinoma of the anus: a retrospective analysis. Int J Radiat Oncol Biol Phys. 1999 Dec 1;45(5):1199-205. Available at: http://dx.doi.org/10.1016/S0360-3016(99)00267-9.

Choi-Baisi classification for bronchoscopic findings in esophageal cancer

This classification allows to identify bronchoscopic findings that predict resectability of esophageal carcinoma [1-3].

Category I: No abnormalities [2].

Category II: Impingement and no mucosal changes [2].

Category IIa: "(...) slight compression on the posterior wall of the trachea or left bronchus and no tumorous infiltration of the tracheobronchial tree; normal mobility of the tracheobronchial wall; and parallel and regular longitudinal folds of the pars membranacea. (...) This group of patients can be identified because the compression on the involved tracheobronchial tree is usually slight and its mobility is normal. (...) The tracheobronchial tree is only compressed and not infiltrated by the tumor, thus making a radical resection possible" [1].

Category IIb: "(...) compression in which the fixation of the tracheobronchial tree suggests tumorous invasion; impingement or deviation of the trachea or left bronchus or widening of the carina, with or without narrowing, associated with a reduction in mobility during breathing and coughing (ie, fixation of the involved tracheobronchial segment). The mucosa is still normal, but the longitudinal folds of the pars membranacea may be widened. (...) There is a frank infiltration of the tracheobronchial tree and a radical resection is unlikely. These patients can be downstaged by appropriate neoadjuvant" treatment "that would then make radical resection feasible" [1].

Category III: Mucosal invasion [2]/irregularities or tracheoesophageal fistula [3].

Bibliographic references:

[1] Baisi A, Bonavina L, Peracchia A. Bronchoscopic staging of squamous cell carcinoma of the upper thoracic esophagus. Arch Surg. 1999;134(2):140-143. Available at: http://dx.doi.org/10.1001/archsurg.134.2.140.

[2] Choi  TKSiu  FSLam  KWong  J Bronchoscopy and carcinoma of the esophagus, I: findings of bronchoscopy in carcinoma of the esophagus. Am J Surg. 1984;147(6):757-759. Available at: http://dx.doi.org/10.1016/0002-9610(84)90194-6.

[3] Choi  TKSiu  FSLam  KWong  J Bronchoscopy and carcinoma of the esophagus, II: carcinoma of the esophagus with tracheobronchial involvement. Am J Surg. 1984;147(6):760-762. Available at: http://dx.doi.org/10.1016/0002-9610(84)90195-8.

Efficacy

It "is the extent to which a specific intervention, procedure, or service produces the desired effect, under ideal conditions (controlled environment, laboratory circumstances)." Efficacy is equal to effectiveness; only circumstances change. For example, "the efficacy of vaccine A was achieved under ideal laboratory circumstances, yet, its effectiveness needs to be shown."

Bibliographic references: Hayajneh.org. (n.d.). Effectiveness, Efficiency, and Efficacy : Definition - Health Care and Health Care Informatics Terms - Define Efficiency, Effectiveness, and Efficacy. [online] Available at: http://www.hayajneh.org/glossary/vocabulary/e/EfficiencyEffectivenessEfficacy.html [Accessed 2 Jul. 2016].

Efficiency

It "is the ratio of the output to the inputs of any system. An efficient system or person is one who achieves higher levels of performance (outcome, output) relative to the inputs (resources, time, money) consumed."

Bibliographic reference: Hayajneh.org. (n.d.). Effectiveness, Efficiency, and Efficacy : Definition - Health Care and Health Care Informatics Terms - Define Efficiency, Effectiveness, and Efficacy. [online] Available at: http://www.hayajneh.org/glossary/vocabulary/e/EfficiencyEffectivenessEfficacy.html [Accessed 2 Jul. 2016].

Effectiveness

It "is the extent to which planned outcomes, goals, or objectives are achieved as a result of an activity, strategy, intervention or initiative intended to achieve the desired effect, under ordinary circumstances (not controlled circumstances such as in laboratory)." For example, "a vaccine is effective when it is capable to produce the desired effect (protection against disease) in the population, under ordinary circumstances. Being effective means achieving organizational goals. Being efficient means achieving goals with little wasted resources. Effectiveness comes first."

Bibliographic reference: Hayajneh.org. (n.d.). Effectiveness, Efficiency, and Efficacy : Definition - Health Care and Health Care Informatics Terms - Define Efficiency, Effectiveness, and Efficacy. [online] Available at: http://www.hayajneh.org/glossary/vocabulary/e/EfficiencyEffectivenessEfficacy.html [Accessed 2 Jul. 2016].

Putative gene

It refers to a nucleotide sequence believed to be a gene because of its open reading frame although its function and the protein it codes for has not been (fully) identified [1]. For example, putative gene 57 is the (temporary) name suggested for the gene coding for a protein produced by Bacteriophage SP01 that infects the bacterium Bacillus subtilis [2]. Another example: PTEN, a putative protein tyrosine phosphatase gene mutated in some cancers [3].

Bibliographic references:

[1] Biology-online.org. (2014). Putative - Biology-Online Dictionary. [online] Available at: http://www.biology-online.org/dictionary/Putative [Accessed 26 Jun. 2016].

[2] Stewart CR, Gaslightwala I, Hinata K, Krolikowski KA, Needleman DS, Peng AS, et al. Genes and regulatory sites of the "host-takeover module" in the terminal redundancy of Bacillus subtilis bacteriophage SPO1. Virology. 1998 Jul 5; 246 (2): 329-40. Available at: http://dx.doi.org/10.1006/viro.1998.9197.

[3] Li J, Yen C, Liaw D, Podsypanina K, Bose S, Wang SI, et al. PTEN, a putative protein tyrosine phosphatase gene mutated in human brain, breast, and prostate cancer. Science. 1997 Mar 28;275(5308):1943-7. Available at: http://dx.doi.org/10.1126/science.275.5308.1943.

Recurrence (or relapse)

It is the reappearance of cancer after a disease-free period [1,2]. Cancer that has recurred (come back), usually after a period of time during which the cancer could not be detected. The cancer may come back to the same place as the original (primary) tumor or to another place in the body [3]. Generally, it is the return of a disease or the signs and symptoms of a disease after a period of improvement [4].

Relapse (not recurrence) also refers to returning to the use of an addictive substance or behavior, such as cigarette smoking [4].

Bibliographic references:

[1] CureSearch for Children's Cancer. (n.d.). Relapse or Recurrence. [online] Available at: http://curesearch.org/Relapse-or-Recurrence [Accessed 25 Jun. 2016].

[2] CureSearch for Children's Cancer. (2015). relapse. [online] Available at: http://curesearch.org/glossary/relapse/ [Accessed 25 Jun. 2016].

[3] National Cancer Institute. (n.d.). NCI Dictionary of Cancer Terms. [online] Available at: http://www.cancer.gov/publications/dictionaries/cancer-terms?CdrID=45861 [Accessed 25 Jun. 2016].

[4] National Cancer Institute. (n.d.). NCI Dictionary of Cancer Terms. [online] Available at: http://www.cancer.gov/publications/dictionaries/cancer-terms?cdrid=45866 [Accessed 25 Jun. 2016].

TARGIT (targeted intraoperative radiotherapy)

It is a technique of giving radiotherapy to the tissues surrounding a cancer after its surgical removal. In patients having lumpectomy for breast cancer, the TARGIT-A(lone) randomized controlled trial [1] tested whether TARGIT within a risk-adapted approach was non-inferior to conventional course of external beam postoperative radiotherapy given over several weeks. The conclusion was TARGIT concurrent with lumpectomy should be considered an option for eligible patients [2]. The ongoing TARGIT-B(oost) randomized controlled trial is testing whether TARGIT tumour bed boost given after lumpectomy for breast cancer in younger patients or those with a high risk of recurrence is superior to conventional external beam radiotherapy boost for breast cancer [3].

The TARGIT technique is performed by low energy X-rays (50kV maximum) at the tip of a tube. The radiation source is inserted into the tumour bed immediately after excision of the tumour and switched on for 20-35 minutes to provide intra-operative radiotherapy accurately targeted to the tissues that are at highest risk of local recurrence [4].

Other nomenclatures: TARGIT-BQR (boost quality registry) [5], TARGIT-C (consolidation) [5], TARGIT-D (ductal carcinoma in situ) [6], TARGIT-E (elderly) [7], TARGIT-R (retrospective) [8], TARGIT-US (United States) [9].

Bibliographic references:

[1] Vaidya JS, Wenz F, Bulsara M, Tobias JS, Joseph DJ, Keshtgar M, et al;  TARGIT trialists' group. Risk-adapted targeted intraoperative radiotherapy versus whole-breast radiotherapy for breast cancer: 5-year results for local control and overall survival from the TARGIT-A randomised trial. Lancet. 2014 Feb 15;383(9917):603-13. Available at: http://dx.doi.org/10.1016/S0140-6736(13)61950-9.

[2] En.wikibooks.org. (2016). Radiation Oncology/Breast/Partial breast irradiation - Wikibooks, open books for an open world. [online] Available at: https://en.wikibooks.org/wiki/Radiation_Oncology/Breast/Partial_breast_irradiation [Accessed 25 Jun. 2016].

[3] Wikipedia. (2016). Targeted intra-operative radiotherapy. [online] Available at: https://en.m.wikipedia.org/wiki/Targeted_intra-operative_radiotherapy [Accessed 25 Jun. 2016].

[4] Ucl.ac.uk. (2016). TARGIT-B. [online] Available at: http://www.ucl.ac.uk/silva/surgical-interventional-trials-unit/trials/breast/targit-trials/targit-b [Accessed 25 Jun. 2016].

[5] Sperk E, Astor D, Keller A, Welzel G, Gerhardt A, Tuschy B, et al. A cohort analysis to identify eligible patients for intraoperative radiotherapy (IORT) of early breast cancer. Radiat Oncol. 2014; 9: 154. Available at: http://dx.doi.org/10.1186%2F1748-717X-9-154.

[6] Williams, N. and Reynolds, C. (2014). Treating Patients with TARGIT. In: M. Keshtgar, K. Pigott and F. Wenz, ed., Targeted Intraoperative Radiotherapy in Oncology, 1st ed. Springer-Verlag Berlin Heidelberg, pp.141-145.

[7] Neumaier C, Elena S, Grit W, Yasser AM, Uta KT, Anke K, et al. TARGIT-E(lderly)--prospective phase II study of intraoperative radiotherapy (IORT) in elderly patients with small breast cancer. BMC Cancer. 2012 May 8;12:171. Available at: http://dx.doi.org/10.1186/1471-2407-12-171.

[8] Valente SA, Tendulkar RD, Cherian S, O'Rourke C, Greif JM, Bailey L, et al. TARGIT-R (Retrospective): North American Experience with Intraoperative Radiation Using Low-Kilovoltage X-Rays for Breast Cancer. Ann Surg Oncol. 2016 May 9. Available at: http://dx.doi.org/10.1245/s10434-016-5240-1.

[9] Clinicaltrials.gov. (2016). Targeted Intraoperative Radiotherapy United States (TARGIT-US) Registry Trial - Full Text View - ClinicalTrials.gov. [online] Available at: https://clinicaltrials.gov/ct2/show/NCT01570998 [Accessed 25 Jun. 2016].