Friday, 17 November 2017

Mesorectal fascia (MRF)

In total mesorectal excision (TME), «the entire mesorectal compartment including the rectum, surrounding mesorectal fat, perirectal lymph nodes, and its envelope, the MRF, is completely removed by precise dissection along anatomical planes [1].»«The mesorectal fat is surrounded by the MRF, (...) [1].» It surrounds the mesorectal fat outside the rectum or the sphincters in the lowest part [2]:
Source: The Radiology Assistant: Rectal Cancer - MR staging 2.0. Radiologyassistantnl. Available at: http://www.radiologyassistant.nl/en/p56195b237699d/rectal-cancer-mr-staging-20.html. Accessed November 17, 2017.

Source: The Radiology Assistant: Rectal Cancer - MR staging 2.0. Radiologyassistantnl. Available at: http://www.radiologyassistant.nl/en/p56195b237699d/rectal-cancer-mr-staging-20.html. Accessed November 17, 2017.

«The MRF is only circumferential in the low-rectum below the anterior peritoneal reflection.The MRF does not apply to the anterior peritonealized surface of the anterior mid- and high rectum [1]»:
Source: The Radiology Assistant: Rectal Cancer - MR staging 2.0. Radiologyassistantnl. Available at: http://www.radiologyassistant.nl/en/p56195b237699d/rectal-cancer-mr-staging-20.html. Accessed November 17, 2017.

«The MRF plays a crucial role in the treatment planning. In TME the mesorectal fascia is the resection plane and it has to be tumor-free. A distance of the tumor to the mesorectal fascia of ⩽1 mm is regarded as not suitable for TME and is called an involved MRF [1].»
Source: The Radiology Assistant: Rectal Cancer - MR staging 2.0. Radiologyassistantnl. Available at: http://www.radiologyassistant.nl/en/p56195b237699d/rectal-cancer-mr-staging-20.html. Accessed November 17, 2017.

T-stage and mesorectal fascia involvement in the axial plane
Source: The Radiology Assistant: Rectal Cancer - MR staging 2.0. Radiologyassistantnl. Available at: http://www.radiologyassistant.nl/en/p56195b237699d/rectal-cancer-mr-staging-20.html. Accessed November 17, 2017.

«Low rectal cancer has a higher local recurrence rate. The distal tapering of the mesorectal fat implies that low rectal cancer more easily invades the MRF, pelvic wall, and surrounding organs [1]»:
Source: The Radiology Assistant: Rectal Cancer - MR staging 2.0. Radiologyassistantnl. Available at: http://www.radiologyassistant.nl/en/p56195b237699d/rectal-cancer-mr-staging-20.html. Accessed November 17, 2017.

«The low rectum is totally covered by the mesorectal fascia. In the mid-rectum, it is covered by the mesorectal fascia on the posterior and lateral side, but on the anterior side, it is covered by the visceral peritoneum [1].»
Bibliographic references:
[1] The Radiology Assistant: Rectal Cancer - MR staging 2.0. Radiologyassistantnl. Available at: http://www.radiologyassistant.nl/en/p56195b237699d/rectal-cancer-mr-staging-20.html. Accessed November 17, 2017.
[2] Glimelius B, Beets-Tan R, Blomqvist L, et al. Mesorectal fascia instead of circumferential resection margin in preoperative staging of rectal cancer. J Clin Oncol. 2011 Jun 1;29(16):2142-3. Available at: https://doi.org/10.1200/JCO.2010.34.4473.

UICC

Union for International Cancer Control

Circumferential resection margin

«The circumferential resection margin (CRM) is a term used in rectal carcinoma excision surgery. Pathologic evaluation of the resection margin on the excised rectum has been considered important for determining the risk of local recurrence. A margin of ≤1 mm is considered by some to be a negative prognostic factor for local recurrence (Park JS, et al., 2014, apud 1). (...). The CRM is not valid for excised colon covered by a peritoneal lining [1].» It is defined as the shortest distance from an affected region to the mesorectal fascia (MRF) and should be at least 1 mm [2]. It also called the radial margin. 
Bibliographic references:
[1] Weerakkody Y, Morgan M, et al. Circumferential resection margin | Radiology Reference Article | Radiopaedia.org. Radiopaediaorg. Available at: https://radiopaedia.org/articles/circumferential-resection-margin. Accessed November 17, 2017.
[2] Bond S, Joshi N, Petroudi S, Brady M. Estimating the mesorectal fascia in MRI. Inf Process Med Imaging. 2007;20:650-61. Available at: https://doi.org/10.1007/978-3-540-73273-0_54.

Sunday, 12 November 2017

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.

Tuesday, 7 November 2017

Blogs Portugal

Há pouco tempo, aderi à plataforma Blogs Portugal (https://blogsportugal.come fiquei surpreendida com o ranking nacional deste blog, o Radiotherapy Dictionary. Além disso, a plataforma Blogs Portugal permite classificar os blogs portugueses no geral e por categorias e aceder a muitos benefícios, por intermédio de campanhas e através da divulgação dos blogs aderentes. Blogueiros, experimentem! (Portuguese)

Not long ago, I joined the platform Blogs Portugal and I was surprised by the national ranking of this blog, the Radiotherapy Dictionary. In addition, the Blogs Portugal platform allows ranking Portuguese blogs in general and by categories and access to many benefits, through campaigns and through the dissemination of blogs. Bloggers, try!

When cells go bad

When cells go bad

Monday, 6 November 2017

CTLA-4 (CD152)

The cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), or cluster of differentiation 152 (CD152), is a receptor on activated T cells that, functioning as an immune checkpoint, downregulates immune responses. It is constitutively expressed in regulatory T cells but only upregulated in conventional T cells after activation. It acts as an off switch when bound to CD80 or CD86 on the surface of antigen-presenting cells [2]. It binds B7 molecules with a higher affinity than CD28, downregulating T-cell responses by inhibiting CD28 signaling [1].
CD80/CD86 are members of the immunoglobulin superfamily and present on mature antigen-presenting cells. They share their ligands (CD28 and CTLA-4) on T cells and play a major role as costimulatory molecules in the major histocompatibility complex class II-mediated peptide antigen presentation [1].
B7 molecules are a family of cell-surface proteins that function as costimulatory molecules transducing second signals for T cell-dependent immune responses [1].
CD28 is an activating receptor for B7 molecules present on naive T cells. The interaction of CD28 with B7 molecules provides the costimulatory or second signal for T-cell activation [1].
«(...) there is increasing interest in the possible therapeutic benefits of blocking CTLA-4 (using antagonistic antibodies against CTLA such as ipilimumab (FDA [Food and Drug Administration] approved for melanoma in 2011) as a means of inhibiting immune system tolerance to tumours and thereby providing a potentially useful immunotherapy strategy for patients with cancer» [2].
Bibliographic references:
[1] Tortora, G., Bergmann, L., Lindh, M., Cervantes-Ruiperez, A., Dziadziuszko, R., Eckhardt, S., Lenz, H., Normanno, N., Perez, D., Scarpa, A., Syrigos, K., Tabernero, J. and Troiani, T. (2014). ESMO glossary in molecular biology of cancer. Viganello-Lugano, Switzerland: European Society for Medical Oncology.
[2] CTLA-4. Enwikipediaorg. 2017. Available at: https://en.wikipedia.org/wiki/CTLA-4. Accessed November 6, 2017.

Thursday, 19 October 2017

PSA (prostate specific antigen) density

PSA density (ng/mLor ng/mL/cc) is calculated preoperatively during the biopsy procedure by using transrectal ultrasound by dividing the maximum preoperative PSA value and prostate volume [1]. The latter is calculated based on the ellipse dimension theory formula [2] (D1 × D2 × D3 × pi/6), where D1 is the maximum transverse diameter, D2 is the maximum anteroposterior diameter, D3 is the maximum longitudinal diameter, and pi is a mathematical constant approximately equal to 3.14.
A study of a large cohort of patients (1662 patients) found a significant trend of worsening pathological features as PSA density increases [3]. Other studies [4,5] found that PSA density (using a pathological weight of the surgical specimen) was a better predictor of extracapsular disease, positive surgical margins, seminal vesicle invasion, lymph node invasion and biochemical recurrence than PSA.
«It is used because an elevated PSA might not arouse suspicion in a man with a very enlarged prostate. The use of PSA density to interpret PSA results is controversial because prostate cancer might be overlooked in a man with an enlarged prostate» [6].
Bibliographic references:
[1] Sfoungaristos S, Perimenis P. Evaluating PSA Density as a Predictor of Biochemical Failure after Radical Prostatectomy: Results of a Prospective Study after a Median Follow-Up of 36 Months. ISRN Urol. 2013 May 16;2013:984951. Available at: https://doi.org/10.1155/2013/984951.
[2] Wolff JM, Boeckmann W, Mattelaer P, et al. Determination of prostate gland volume by transrectal ultrasound: correlation with radical prostatectomy specimens. Eur Urol. 1995;28(1):10-2. Available at: https://doi.org/10.1159/000475012.
[3] Kundu SD, Roehl KA, Yu X, et al. Prostate specific antigen density correlates with features of prostate cancer aggressiveness. J Urol. 2007 Feb;177(2):505-9. Available at: https://doi.org/10.1016/j.juro.2006.09.039.
[4] Freedland SJ, Wieder JA, Jack GS, et al. Improved risk stratification for biochemical recurrence after radical prostatectomy using a novel risk group system based on prostate specific antigen density and biopsy Gleason score. J Urol. 2002 Jul;168(1):110-5. Available at: http://dx.doi.org/10.1016/S0022-5347(05)64841-0.
[5] Sfoungaristos S, Perimenis P. PSA density is superior than PSA and Gleason score for adverse pathologic features prediction in patients with clinically localized prostate cancer. Can Urol Assoc J. 2012 Feb;6(1):46-50. Available at: https://doi.org/10.5489/cuaj.11079.
[6] Definition of PSA density. Phoenix5org. 2002. Available at: http://www.phoenix5.org/glossary/PSA_density.html. Accessed October 19, 2017.

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 “PSA bounce”» [4]. Biochemical failure after external beam radiotherapy with or without hormonal therapy in men with clinically localized prostate cancer by 2005 RTOG-ASTRO Phoenix Consensus Conference is: 1) prostate-specific antigen (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]. «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].
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.

Sunday, 15 October 2017

AFU

Association Française d’Urologie, the French Association of Urology.

GETUG

Groupe d'Études des Tumeurs Uro-Génitales, the French Genitourinary Study Group.

Electromagnetic tracking system (EMTS)

Image-guided therapy relies on the localization of the equipment with respect to the patient. This localization in three-dimensional space is referred to as tracking and is a key enabling technology for computer-assisted interventions. Electromagnetic (EM) tracking has emerged as the method of choice that enables localization of small EM sensors in a given EM field without the requirement for line-of-sight [3]. The introduction of continuous EM tracking has allowed the intrafraction motion to be measured and corrected in real-time during treatment [2]. When a receiving sensor moving in space, an EMTS can accurately calculate its position and orientation, it can provide dynamic, real-time measuring position and orientation angle [1].
«The term “electromagnetic” to describe the tracking phenomenon arises from the fact that electromagnets are responsible for producing changing or quasi-static magnetic fields, which induce currents in solenoids or fluxgate sensors embedded in the detectors. The phenomenon responsible for the operation of these tracking systems relies solely on magnetic induction rather than any strict electromagnetic effect. Nevertheless, while this technology is referred to by both the terms “magnetic tracking” (MT) and “electromagnetic tracking” (EMT), the latter has become the more common, having been adopted by the manufacturers of these devices, (...) [3].»
Bibliographic references:
[1] Zhang Z, Liu G. The Design and Analysis of Electromagnetic Tracking System. Journal of Electromagnetic Analysis and Applications. 2013;5:85-9. Available at: http://dx.doi.org/10.4236/jemaa.2013.52014.
[2] Litzenberg DW, Gallagher I, Masi KJ, et al. A measurement technique to determine the calibration accuracy of an electromagnetic tracking system to radiation isocenter. Med Phys. 2013 Aug;40(8):081711. Available at: https://doi.org/10.1118/1.4813910.
[3] Franz AM, Haidegger T, Birkfellner W, et al. Electromagnetic tracking in medicine - a review of technology, validation, and applications. IEEE Trans Med Imaging. 2014 Aug;33(8):1702-25. Available at: https://doi.org/10.1109/TMI.2014.2321777.

SPECT (single photon emission computed tomography)

SPECT, or less commonly, SPET [3], is a medical imaging technique that is based on conventional nuclear medicine imaging, using gamma rays, and tomographic reconstruction methods. It is «performed by using a gamma camera to acquire multiple two-dimensional (2D) images from multiple angles» [4]. «The images reflect functional information about patients similar to that obtained with positron emission tomography (PET). Both SPECT and PET (...) give information based on the spatial concentration of injected radiopharmaceuticals» [1]. It «is a type of nuclear imaging test that shows how blood flows to tissues and organs» [2]. It is very similar to conventional nuclear medicine planar imaging using a gamma camera (that is, scintigraphy), but, it is able to provide true three-dimensional (3D) information [3]. A computer is used to apply a tomographic reconstruction algorithm to the multiple 2D projections, yielding a 3D dataset. «This dataset may then be manipulated to show thin slices along any chosen axis of the body» [4]. SPECT can be used to complement any gamma imaging study, where a true 3D representation can be helpful, (e.g., tumor imaging, infection (leukocyte) imaging, thyroid imaging or bone scintigraphy). Because SPECT permits accurate localization in 3D space, it can be used to provide information about the localized function in internal organs, such as functional cardiac or brain imaging [3].
Bibliographic references:
[1] National Research Council (US) and Institute of Medicine (US) Committee on the Mathematics and Physics of Emerging Dynamic Biomedical Imaging. Mathematics and Physics of Emerging Biomedical Imaging. Washington (DC): National Academies Press (US); 1996. Chapter 5, Single Photon Emission Computed Tomography. Available at: https://www.ncbi.nlm.nih.gov/books/NBK232492/. Accessed October 15, 2017.
[2] SPECT (single photon emission computed tomography) scan. Mayfield Brain & Spine. 2016. Available at: https://www.mayfieldclinic.com/PE-SPECT.htm. Accessed October 15, 2017.
[3] Single-photon emission computed tomography. Enwikipediaorg. 2017. Available at: https://en.wikipedia.org/wiki/Single-photon_emission_computed_tomography. Accessed October 15, 2017.
[4] Hricak H, Akin O, Vargas HA. (2013). C. In: L. Brady and T. Yaeger, ed., Encyclopedia of Radiation Oncology, 1st ed. Springer-Verlag Berlin Heidelberg, pp.790.

Monday, 25 September 2017

Dia do Interno Radioncologia (Portuguese) (Radiation Oncology Resident's Day)




  • Venue: October 20, 2017 - Hospital de Santa Maria, Centro Hospitalar Lisboa Norte, EPE, Lisbon, Portugal: