Radiotherapy external beam

The two commonly used methods for radiation therapy are external-beam radiotherapy and brachytherapy.26 In external-beam radiotherapy, doses of 70 to 75 Gy are delivered in 35 to 41 fractions in patient with low-grade prostate cancer and 75 to 80 Gy for those with intermediate- or high-grade prostate cancer. Brachytherapy involves the permanent implantation of radioactive beads of 145 Gy of 125I or 124 Gy of 103Pd and generally is reserved for individuals with low-risk cancers. 

External beam radiotherapy Treatment by radiation emitted from a source located at a distance from the body also called beam therapy and external beam therapy. 

Radiotherapy is a local treatment aiming to achieve local control or cure of locally confined tumours. It cannot treat metastases. Radiotherapy may be administered as external beam radiotherapy with X-rays or gamma rays, in sealed radioactive sources (e.g. prostate brachytherapy), or unsealed sources (e.g. orally administered radioiodine for thyroid cancer, intravenous strontium-89 for bone metastases). In external beam radiotherapy, the X-ray or gamma ray beams are targeted at the tumour to damage and kill the tumour cells. Inevitably, surrounding normal tissues are also affected resulting in the early and late side effects of radiotherapy. 

Warde P, O Sullivan B, Bristow R, et al. T1/T2 glottic cancer managed by external beam radiotherapy the influence of pretreatment hemoglobin on local control. Int J Rad One Biol Phys 1998 41(2) 347-353. 

Aygun C, Weiner S, Scariato A, et al. Treatment of non-small cell lung cancer with external beam radiotherapy and high dose rate brachytherapy. Int J Radiat Oncol Biol Phys 1992 23 127-132. 

Pollack A, Zagars GK, Swanson DA. Muscle-invasive bladder cancer treated with external beam radiotherapy prognostic factors, ltd J Rad Oncol Biol Phys 1994 2 267-277. 

Pisansky TM. External-beam radiotherapy for localized prostate cancer. N Engl J Med. 2006 355 1583. 

Crook JM, Bahadur YA, Robertson SJ, et al. Evaluation of radiation effect, tumor differentiation, and prostate specific antigen staining in sequential prostate biopsies after external beam radiotherapy for patients with prostate carcinoma. Cancer. 1997 79 81. 

Therefore, many metastatic thyroid cancers, as well as anaplastic/undifferentiated primary thyroid cancer, do not concentrate 1-131 in quantities that are therapeutically useful. For these patients, treatment options are restricted to surgery or external beam radiotherapy for local symptoms (Niederle et ai, 1986 Kim and keeper, 1983 Tubiana et ai, 1985) and chemotherapy for systemic disease (Kim and keeper, 1983 Shimaoka et ai, 1985 Ain et ai, 1996). All of these approaches have limited success (Tyler et ai, 2000). The response rate to single-agent chemotherapy is... 

Ewend MG, Williams JA, Tabassi K, Tyler BM, Babel KM, Anderson RC, Pinn ML, Brat DJ, Brem H. Local delivery of chemotherapy and concurrent external beam radiotherapy prolongs survival in metastatic brain tumor models. Cancer Res 1996 56 5217-5223. 

Studies of liver effects from external beam radiotherapy date back to the 1920s [13-16]. Brachy-therapy in the lung and liver also has a significant history of investigation [17]. Preclinical studies utilized a variety of animal models, and various infusion methods (vein, heart, aorta, hepatic artery, and portal vein) with and without liver tumors to study microsphere deposition in normal and tumors tissues. Common observations in animals and humans confirmed arterial delivery of microspheres causes them to embed in the periphery of the tumor in highly nonuniform (but not random) patterns with nearly all located within a few millimeters of tumor... 

External beam radiotherapy (including three-dimensional radiotherapy, intensity modulated radiotherapy, and extracranial stereotactic radiotherapy) is the most common way radiation is used to eradicate solid tumors, often with combined chemotherapy. The key limitation of external beam radiotherapy is the tolerance of normal liver parenchyma to radiation, which is much less than the dose required to control the liver tumors. Direct implantation of radionuclides into the tumor (brachytherapy) using interstitial seeds... 

Radiotherapy consists of external beam irradiation of the uninvolved pelvic lymphatics and uninvolved parametrial tissue with a dose of up to 45 Gy and intracavitary brachytherapy with three to six fractions of 4-8 Gy each dehvered to point A or the uterus [62], corresponding to a total dose equivalent of 70-80 Gy delivered to point A. The dose delivered by external beam radiotherapy is adjusted to the local tumor extent and metastatic nodal involvement (boost). A larger field of external irradiation is chosen in patients with para-aortic lymph node metastases. No brachytherapy is done in most patients with infiltration of the bladder or rectum because of the risk of fistula development. Alternatively, cervical cancer with invasion of adj acent pelvic organs can be treated by surgical pelvic exenteration. The most common therapies according to stage are summarized in Table 7.3. 

Gerard et al. 1998 Anal canal carcinoma Tl-4 NO 3 External beam radiotherapy plus implant and chemotherapy 5-Year colostomy-free survival 72% 5-Year disease-specific survival 90%... 

Sathya et al. 2005 T2-3 NO prostate cancer External beam radiotherapy plus implant 8-Year failure-free survival 65% 8-Year overall survival 82%... 

Pollack et al. 2002 Tl-3 prostate cancer External-beam radiotherapy, 78 Gy 6-Year failure-free survival 70%... 

Lertsanguansin-CHAi et al. 2004 Stage IB-IIIB cervical cancer External-beam radiotherapy plus brachytherapy 3-Year pelvic control 87% 3-Year relapse-free survival 70%... 

The results of intracavitary brachytherapy are better than those of external beam radiotherapy. 

Highly targeted radiotherapy ( brachytherapy ) was the first clinical application of stain-etched silicon microparticles. We briefly review here the manufacture, testing, and clinical use of the P Si beta-emitting formulation for unresectable hepatocellular and pancreatic carcinoma. Clinical data Ifom a number of trials suggests that the technology offers patients with inoperable solid tumors an attractive alternative to external beam radiotherapy. 

In patients with prostate cancer undergoing external beam radiotherapy, penile irradiation results in cavernosal damage. In particular, patients receiving at least 70 Gy to the 70% or more of the bulb of the penis have a high risk of developing a radiotherapy-induced erectile dysfunction (Fisch et al. 2001). 

Halyard MY. Randomized control trial evaluating aluminum-based antiperspirant use, axilla skin toxicity, and reported quality of life in women receiving external beam radiotherapy for treatment of stage 0,1, and II breast cancer. Breast Dis 2012 23(4) 369-71. 

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