Sezin Yuce Sari

Adjuvant Small Pelvic Radiotherapy in Patients with Cervical Cancer Having Intermediate Risk Factors Only - Is It Sufficient?

Background: We sought to determine the outcomes of adjuvant small pelvic external beam radiotherapy (EBRT) and prognostic factors for survival and disease control. Patients and Methods: We retrospectively evaluated 113 cervical cancer patients treated with postoperative median 50.4-Gy small pelvic EBRT. We treated the surgical bed, bilateral parametria, paravaginal soft tissues, upper third of the vagina, and presacral lymphatics. Results: Median follow-up of all patients and survivors was 58 and 67 months, respectively. The 2- and 5-year overall survival (OS) and disease-free survival rates were 91 and 82%, and 85 and 74%, respectively. The locoregional failure rate was 10%. Age was a significant predictor for OS and distant metastasis-free survival (DMFS) on univariate analysis. The number of dissected lymph nodes being < 30 negatively affected the pelvic recurrence-free survival. The only independent predictor on multivariate analysis was older age for DMFS. Although no severe acute toxicity was observed, late grade ≥ 3 toxicity developed in 8 patients. Conclusion: Small pelvic EBRT produces satisfactory survival and locoregional control with acceptable toxicity, and can be an alternative to whole pelvic EBRT in selected cervical cancer patients.

Target Volume Delineation Guidelines in Bladder Cancer

The use of radiotherapy (RT) in the treatment of bladder cancer has been decreasing through the years. There is no role of RT in carcinoma in situ and Ta and Tl tumors. However, irradiation may have a role in high-grade or recurrent T1 lesions. There is no prospective randomized trial comparing surgery with RT in muscle-invasive bladder cancer. In T2–T4a disease without lymph node (LN) involvement, RT can be combined with concurrent chemotherapy in medically fit patients. However, there is no rationale of RT in patients with LN or distant metastasis except for palliative reasons. The gross tumor volume (GTV), clinical target volume (CTV), planning target volume (PTV), and organs at risk (OAR) should be delineated separately in each slice based on the recommendations in the International Commission on Radiation Units and Measurements (ICRU) reports 50 and 62. The only delineation guideline for the RT in bladder cancer has been reported by the Australian and New Zealand Faculty of Radiation Oncology Genito-Urinary Group.

Stereotactic Body Radiotherapy for Prostate Cancer

The term stereotactic implies that the target is localized relative to a fixed three-dimensional spatial coordinate system. Stereotactic body radiation therapy (SBRT) is defined as giving a high dose of radiation per fraction, in up to five fractions, using sophisticated image guidance to deliver a potent ablative dose to cancerous tissues while minimizing the risk to normal structures. The alpha-beta ratios for the rectum and bladder, both of which are late-responding tissues, are 2.5–5 Gy and 3–7 Gy, respectively. This unique biologic nature of prostate cancer explains the therapeutic gain with hypofractionation. These radiobiologic assumptions were supported by prospective randomized trials that used 2.5–3.1 Gy per fraction.

Radiation-Induced Toxicity and Related Management Strategies in Urological Malignancies

The lower abdomen and pelvis encompass several organs at risk (OAR), some of which are vital and are inevitably affected during radiotherapy (RT). In this chapter, the contouring recommendations and dose-volume constraints of the rectum, bowel bag (i.e., the whole small and large bowel together with their meso), urinary bladder, penile bulb, proximal femurs, and sacral plexus will be discussed in order to spare these OARs as much as possible during the RT of urological malignancies. Among these OARs, the bowel bag, penile bulb, and sacral plexus are serial organs in which the maximum point dose affects the function of the whole organ. On the other hand, the rectum, bladder, and femurs are in a parallel structure for which the mean dose to a specific volume is more important than the maximum dose. In order to interpret the dose-volume histograms (DVH) precisely, the accurate delineation of OARs is crucial.

Guidelines for the Delineation of Lymphatic Target Volumes in Prostate Cancer

The incidence of regional lymph node (LN) involvement in patients with prostate cancer depends on several factors like the tumor size and the Gleason score (GS). The risk of LN involvement is <10% in low-risk disease. A number of models were developed in order to predict the risk of LN involvement which helps the physicians to decide whether to perform a staging lymphadenectomy or LN irradiation. In this chapter, we will review the current guidelines for the delineation of lymphatic target volumes in prostate cancer.

PSA After Radiotherapy: PSA Bounce and Biochemical Failure

Prostate cancer is one of the major health problems in the world. Active surveillance (AS), radical prostatectomy (RP) or radiotherapy (RT) options can be selected in patients with localized prostate cancer according to risk groups. RT can be given as external beam therapy (EBT) or as brachytherapy (BRT). EBT can be delivered by three-dimensional conformal RT (3BKRT) or intensity modulated RT (IMRT) with conventional fractionation, hypofractionated RT (HFRT), stereotactic body RT (SBRT) and proton treatment. High-dose rate (HDR) or low-dose rate (LDR) BRT can be used as a sole treatment modality or as a combined treatment modality with EBT. Treatment success after local treatment is often evaluated by “biochemical failure.” Approximately one-third of patients undergoing RP and 20–30% of patients treated with EBT and hormonal treatment show local recurrence or biochemical failures.

Functional Imaging-Guided Radiotherapy and Radiolabelled Targeted Therapies in Prostate Cancer

Positron emission tomography (PET) imaging using PSMA ligand is a promising radiotracer in prostate cancer. Recent trials suggest its potential role in accurate staging of high-risk prostate cancer and detecting metastases and local-regional relapses during biochemical recurrence with 68Ga-PSMA positron emission tomography/computed tomography (PET/CT). However, the data related with its role in radiotherapy are still lacking. Therefore, we summarized our experience with 68Ga-PSMA PET/CT guided hypofractionated stereotactic radiotherapy in patients with oligometastatic disease after biochemical recurrence. Radiolabelled targeted therapies gains popularity in the management metastatic bone disease in prostate cancer. We particularly review the applications of radium-223 chloride in prostate cancer patients in the light of available clinically relevant data.

Guidelines for the Delineation of Primary Tumor Target Volume in Prostate Cancer

In recent years, the use of intensity-modulated RT (IMRT) and image-guided RT (IGRT) has increased worldwide. These techniques are highly conformal and the target should be more precise. Therefore, target determination and delineation is crucial in the management of prostate cancer with modern radiotherapy techniques. In this chapter, we will briefly explain the current guidelines for the delineation of primary target volume in prostate cancer.

The Role of Hormonal Treatment in Prostate Cancer

Androgens are endocrine secretions produced mainly by the testes under stimulation of the pituitary gland. They are also synthesized from the adrenal glands in both sexes and from ovaries in females. Luteinizing hormone (LH) produced by the anterior pituitary gland regulates the secretion of androgens from the Leydig cells in the testes. LH secretion is controlled by the hypothalamus via gonadotropin-releasing hormone (GnRH). Androgens play a major role in the development and maintenance of male sex characteristics. The primary and most well-known androgen is testosterone that is rapidly and irreversibly converted to dihydrotestosterone (DHT) in prostate by types 1 and 2 5α-reductase. Androgens stimulate the growth of both normal and cancerous prostate cells by binding to and activating the androgen receptor (AR), a protein that is expressed in prostate cells. Then, AR stimulates the expression of specific genes that cause prostate cells to grow. The role of androgens in prostate cancer was first established in 1941 by Huggins and Hodges. Since then androgen deprivation therapy (ADT) has become the standard of care for patients with advanced prostate cancer. In this chapter ADT and its use in prostate cancer will be discussed.

Radiation-Induced Toxicities and Management Strategies in Thoracic Malignancies

The majority of patients with lung cancer in every histology and stage will receive radiotherapy (RT), either curative or palliative. The aim of the radiation oncologist is to achieve the optimal dose, which will eradicate the malignancy. However, it is also crucial to keep the dose to the organs at risk (OAR) under the tolerance limits, and accurate delineation of these organs is necessary for the correct evaluation of the dose-volume histograms. This chapter aims to guide the radiation oncologists for the delineation of the OARs as well as presenting tolerance dose limits for them.