Utilización de las TIC en la enseñanza y aprendizaje de la Química

1.4.1

Radical treatments

Surgery: Currently, one of the clinical standard PCa treatments is to surgically

remove the whole prostate gland and the attached seminal vesicles, also known as radical prostatectomy. This surgery is usually done for patients with clinically localized PCa that is progressive and aggressive. Some times the local lymph nodes are also removed during the same surgery [44]. Radical prostatectomy is sometimes followed by other treatment or monitoring options such as radiotherapy, chemotherapy, ADT or active surveillance to avoid the risk of PCa recurrence [45].

Since the prostate is surrounded by the sphincter urethrae muscle, as well as nerves and blood vessels that are critical for erections, and is attached to many organs such as rectum and bladder, radical prostatectomy can have severe side effects such as urinary incontinence and erectile dysfunction [46-48]. Prostatectomy has minimal post- surgery bowel function-related symptoms [49]. The NCCN guidelines recommend radical prostatectomy for patients with 10 or more years of estimated life expectancy who do not have any serious health conditions that would contraindicate the surgery [44].

External beam radiation therapy: EBRT is another common radical treatment

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target by a computer-controlled linear accelerator (LINAC). The LINAC targets the prostate and directs the radiation from outside of the body at the prostate gland to kill the cancerous cells. Intensity modulated radiotherapy (IMRT) is one of the state-of-art radiathion therapy methods in radiation oncology used for PCa treatment. With IMRT, compared to traditional radiation therapy, oncologists can plan the radiation therapy with the aim of delivering a higher dose to the tumour and minimizing radiation exposure to the healthy surrounding tissues. For accurate radiation delivery to the target, prostate localization is performed by image-guided radiotherapy (IGRT) [44]. In IGRT, for each radiation delivery secssion the target is tracked by an intra-operative imaging system such as ultrasound imaging, X-ray imaging or cone-beam computed tomography (CT) to increase the accuracy of the targeting and compensate tissue movment.

Prostate EBRT dose planning is usually done under CT image guidance because CT provides 3D anatomical localization of the pelvis and also provides the electron density information of the tissues that is required for radiation dose calculation. Radiation oncologists usually use inverse planning for radiation dose planning in IMRT. In inverse planning the oncologists first delineate the prostate border as well as the surfaces of all organs at risk in 3D. They then use advanced software to prioritize the dose delivery and limitations for the organs at risk and run the software to design the dose plan. The dose plan is used in a computer-controlled LINAC for radiation therapy delivery.

The limitation with CT based planning is the low soft tissue contrast in CT

images. Therefore, CT cannot provide accurate and repeatable contour delineation for the prostate and some of the surrounding organs at risk such as the rectum, bladder and NVBs [50, 51].

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In terms of health-related quality of life (HRQOL), in general, patients who undergo EBRT have less urinary incontinence but worse bowel function compared to prostatectomy patients [52, 53]. HRQOL improves over time post-treatment for PCa patients treated with EBRT [54]. EBRT also avoids surgery-associated risks and complications such as bleeding and transfusion-related risks, and anesthesia-associated side effects [44].

Brachytherapy: Brachytherapy, as an internal radiotherapy, is another radical

treatment method usually used for lower-risk PCa cases [44]. In this method, radioactive sources are placed within the prostate tissue to kill the cancerous cells. Prostate

brachytherapy is an outpatient procedure that is performed under either general or spinal anesthesia. The treatment is usually planned using ultrasound and/or MR imaging. The radioactive sources are usually placed in the prostate through transperineal insertion under the guidance of an imaging technique like TRUS [55].

Low dose-rate (LDR) and high dose-rate (HDR) brachytherapy are the two main types of brachytherapy treatment approaches for PCa. In HDR brachytherapy a catheter is inserted into the prostate and a high-dose radiation is delivered to the cancerous tissue. In LDR brachytherapy a number of small radioactive seeds are permanently implanted in the prostate gland to deliver low dose radiation to the tumour cells within a longer period of time compared to HDR brachytherapy. Brachytherapy as monotherapy is

recommended to patients with low-risk PCa. For intermediate-risk PCa, brachytherapy is combined with EBRT with or without ADT. Brachytherapy rarely is a useful option for high-risk PCa treatment [44].

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Brachytherapy is usually performed within a day and the patient can return to normal activities in a short time [44]. Less erectile dysfunction is reported after brachytherapy compared to EBRT and prostatectomy [49]. The incidence of urinary continence is lower after brachytherapy compared to prostatectomy, and bowel dysfunction is comparable to EBRT [49, 52].

1.4.2

Lesion-directed treatments

In a subset of prostate cancer patients with organ-confined cancer, PCa consists of a dominant high-grade tumour surrounded by primarily non-cancerous tissue. Therefore, a number of emerging therapy methods such as cryotherapy and high intensity focused ultrasound (HIFU) suggest preserving as much healthy parenchyma as possible and delivering the treatment to the tumour site [44]. In these local therapy methods (also known as focal therapies) the treatment is focused on the tumour cells to spare healthy tissues from destruction. This leads to minimally invasive treatments with fewer and less- severe risks and side effects compared to radical treatments like prostatectomy and radiotherapy.