Cancer Treatment Today » Radiation Therapy

IMRT for prostate cancer

M Levin, MD — Sun, 23 Sep 2012 16:56:27 +0000

IMRT is a rapidly evolving technique, which affords a more precise radiation dose delivery of escalated doses, in appropriate cases, to targeted tumors, while sparing nearby healthy tissue structures. The FDA clearance of numerous devices for the technical delivery of IMRT is based on the capability of this technology to incorporate accurate dose calculation algorithms, associated with a verifiable dose distribution, as managed by the treating physician, (i.e., radiation oncologist). Although, to date, no randomized trials have matured to document long-term outcomes data and efficacy for IMRT, the scientific evidence currently available indicates that IMRT permits better treatment planning and sparing of surrounding tissues, which is of particular usefulness with “Radiosensitive” tumors of the head/neck, prostate and CNS lesions where the target volume is in close proximity to critical healthy structures that must be protected. These results may be extrapolated to the treatment of other cancers at other anatomic sites; however, a number of technical issues need to be resolved before IMRT can be recommended routinely for lung cancer use, particularly the issue of tumor mobility must be addressed, (e.g., a lung tumor moving with respiration)” . CCited from: htttp://atc.wustl.edu/home/NCI/NCI_IMRT_Guidelines_2006.pdf

Currently, there are no randomized controlled trials of IMRT compared with other radiation techniques for treatment of prostate cancer. This means that the evidence to support IMRT is less than conclusive. It can be said that it causes less toxicity but that it produces beter outcome cannot be concluded. Non-randomized studies consistently demonstrate reduced rates of toxicity in IMRT-treated patients. The 2010 Agency for Healthcare Research and Quality (AHRQ) comparative evaluation of radiation treatments for clinically localized prostate cancer concluded that data on comparative effectiveness between different forms of radiation treatments are inconclusive with respect to overall or disease-specific survival. In addition, the AHRQ technology assessment states that more studies of better quality are needed to confirm or refute the suggested findings in the studies that compared outcomes in patients treated with different forms of radiation therapy.

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Hyperbaric oxygen for osteonecrosis of the jaw

M Levin, MD — Thu, 20 Sep 2012 14:40:04 +0000

Osteonecrosis, death of bone tissues, is a well known complication that can occur in different bones. Osteonecrosis of the jaw is a known complication on of several medical interventions, such as radiation and biphosphonates. It had been initially described with the biphosphonate Fosomax but began to be seen more frequently with the intravenous biphosphonates, such as Zometa. Conservative treatment is successful in approximately 50% of patients and consists of local rinses, antibiotics, and cessation of biphosphonates. Unfortunately some patients evidence progressive necrosis despite therapy and almost a half fail to completely heal. For this reason there is a great deal of interest in hyperbaric oxygen, as a therapy that has shown effectiveness front nonhealing wounds of various types as well as for osteonecrosis caused by radiation. Unfortunately, for osteonecrosis after biphosphonate use, the supporting evidence remains case reports and case series A 2006 American Association of Oral and Maxillofacial Surgeons Position Paper on Bisphosphonate-Related Osteonecrosis of the Jaws failed to recommend this therapy because of the lack of evidence.

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Stereotactic radiosurgery of lung

M Levin, MD — Fri, 24 Aug 2012 17:48:02 +0000

Stereotactic body radiation therapy (SBRT) is a technique that utilizes precisely targeted radiation to a tumor while minimizing radiation to adjacent normal tissue. This targeting allows treatment of small- or moderate-sized tumors in either a single or limited number of dose fractions. Stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT) initially was used successfully forbrain cacners and malformations, orbital, and base of skull tumors, as well as benign conditions that can use the skull as a reference system. The success of SRS for intracranial indications led to the development of techniques to extend this approach to targets outside of the skull, such as lung cancer. Stereotactic radiation therapy for other body sites iwas enabled by technical advances including tumor imaging to guide radiation administration, patient immobilization, and conformal radiation delivery techniques.

The usual use for SBRT for lung cancer is to attempt a cure or occasionally to control symptomatic lung metastases. It should be realized that this is not a treatment that is free from potential side effects. American Society for Therapeutic Radiation and Oncology (ASTRO, 2007) stated that SBRT is considered appropriate for the treatment of the following conditions:

Lung or liver metastases not amenable to surgery
Medically inoperable early stage lung cancer
Primary liver cancer not amenable to surgery
Recurrent lung cancer amenable to salvage therapy
Recurrent pelvic tumors
Retroperitoneal tumors
Spinal and para-spinous tumors
Other recurrent cancers or tumors.

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Post-mastectomy Radiation

M Levin, MD — Mon, 20 Aug 2012 19:42:59 +0000

The rationale for post-mastectomy radiation(PMRT) is to decrease the chance that cells left behind will regrow in the remaining skin or tissue after mastectomy. Although this is not a common complication, when it ocurrs, it can be devastating. Although the concern is understandable, post-mastectomy radiation tends to be overused in theUSA. For example, women who have stage I or II disease with spread to no more than three lymph nodes and who did not undergo radiation therapy, have the overall growth rate in the same general area rate of just 2.3% at 10 years. A 2005 meta-analysis looked at randomized trials conducted between 1964 and 1984. The analysis determined that post-mastectomy radiation in these women resulted not only in about a 66% reduction in locoregional recurrence compared with no radiation, but also about a 5% survival advantage. However, the overall recurrence rate in those studies ranged from 20% to 25%, much higher than observed in the present.

Certainly, locoregional PMRT is recommended for women with an advanced primary tumour (tumour size 5 cm or greater, or tumor invasion of the skin, pectoral muscle or chest wall) or with 4 or more positive axillary lymph nodes, because the risk of regrwth is significant. However, the role of PMRT in women with 1 to 3 positive axillary lymph nodes is unclear. Locoregional PMRT is generally not recommended for women who have tumors that are less than 5 cm in diameter and who have negative axillary nodes. Other patient, tumor and treatment characteristics, including age, histologic grade, iinvasion of lymph and neural stands, hormone receptor status, number of axillary nodes removed, extension of cancer out of the capsule of lymph nodes in the armpit extension and surgical margin status, may affect loco-regional control, but their use in specifying additional indications for PMRT is currently unclear.

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Post-mastectomy Radiation – pro

M Levin, MD — Mon, 20 Aug 2012 19:38:34 +0000

Post-mastectomy radiation tends to be overused in the USA. For example, women who have stage I or II disease with spread to no more than three lymph nodes and who did not undergo radiation therapy, have the overall locoregional recurrence rate of just 2.3% at 10 years. A 2005 meta-analysis looked at randomized trials conducted between 1964 and 1984. The analysis determined that postmastectomy radiation in these women resulted not only in about a 66% reduction in locoregional recurrence compared with no radiation, but also about a 5% survival advantage. However, the overall recurrence rate in those studies ranged from 20% to 25%, much higher than observed in the present.

Certainly, locoregional PMRT is recommended for women with an advanced primary tumour (tumour size 5 cm or greater, or tumour invasion of the skin, pectoral muscle or chest wall) or with 4 or more positive axillary lymph nodes. However, the role of PMRT in women with 1 to 3 positive axillary lymph nodes is unclear. Locoregional PMRT is generally not recommended for women who have tumours that are less than 5 cm in diameter and who have negative axillary nodes. Other patient, tumour and treatment characteristics, including age, histologic grade, lymphovascular invasion, hormone receptor status, number of axillary nodes removed, axillary extracapsular extension and surgical margin status, may affect locoregional control, but their use in specifying additional indications for PMRT is currently unclear.

Pauline T. Truong,Clinical practice guidelines for the care and treatment of breast cancer: 16. Locoregional post-mastectomy radiotherapy CMAJ April 13, 2004 vol. 170 no. 8

Sharma R, et al “Present day locoregional recurrence rates (LRR) in patients with T1 and T2 breast cancer (BC) with zero and one to three lymph node (LN) metastases following mastectomy without radiation” SSO 2010; Abstract 47

Taylor ME, Haffty BG, Rabinovitch R, Arthur DW, Halberg FE, Strom EA, White JR, Cobleigh MA, Edge SB, Expert Panel on Radiation Oncology-Breast. ACR Appropriateness Criteria® postmastectomy radiotherapy. [online publication]. Reston (VA): American College of Radiology (ACR); 2008. 17 p. [96 references]

Postmastectomy Radiotherapy: Clinical Practice Guidelines of the American Society of Clinical OncologyJournal of Clinical Oncology, Vol 19, Issue 5 (March), 2001: 1539-1569

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Brachytherapy for Prostate Cancer

M Levin, MD — Thu, 16 Aug 2012 20:18:14 +0000

Prostate brachytherapy is among several roughly comparable options for front line treatment of localized prostate cancer available at this time. Unfortunately, there had not been a comparative prospective trial comparing external radiation, seed implants, brachytherapy, robotic prostatectomy, nerve sparing prostatectomy or conventional prostatectomy, proton beam radiotherapy and hormonal manipulation. Look-back reviews of past studies show these options to be similarly effective. A 2008 research summary by the Agency for Healthcare Research and Quality (AHRQ) noted that no randomized controlled trials had compared brachytherapy with other major treatment options for clinically localized prostate cancer. Currently, brachytherapy is widely used but with external beam radiotherapy( EBRT) support. The reason for it is that brachytherapy delivers radiation over very small distances. It does not, for example, get enough radiation to the outer part of the prostate. EBRT treats the areas in which radiation distribution from brachytherapy is decreased. High dose approaches and combinations with other treatments may do what ERBT currently does. Whether some patients can avoid EBRT is being investigated.

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Proton Beam Radiotherapy

M Levin, MD — Thu, 19 Jul 2012 03:07:11 +0000

Charged-particle beams consisting of protons or helium ions are a type of radiation therapy that uses particles which is different from conventional radiation that uses electromagnetic (i.e., photon) radiation. Particles have the unique properties of minimal scatter as the particulate beams pass through the tissue. As such, there is less “collateral damage” to the surrounding tissue and it is possible to ensure a more precise deposition of the ionizing energy at a precise depth, the so called Bragg Peak. The theoretical advantages of protons and other charged-particle beams may improve outcomes but this has not been proven. At the same time proton beam radiotherapy is significantly more expensive than other modalities.

Another disadvantage of proton beam therapy (PBT)is that the equipment that can produce it is very expensive, ensuring that it is only available in a limited number of academic centers.

Australia and New Zealand Horizon Scanning Network (2006) stated that PBT “may be of particular benefit” in the treatment of patients with intermediate depth tumors such as those in the head, cancers that are located in difficult or dangerous-to-treat areas, and tumors in locations where “conventional radiotherapy would damage surrounding tissue to an unacceptable level” (e.g., central nervous system (CNS) and head). PBT “may be ideal for use in the treatment of pediatric patients where the need to avoid secondary tumors is important due to the potentially long life span after radiation treatment when they may develop radiation induced malignancies.

A report by the American Society of Therapeutic Radiology (ASTRO) Emerging Technologies Committee states that there is reason to be optimistic about the potential developments in proton beam therapy (PBT) and the prospective research that is ongoing at centers worldwide. Current data do not provide sufficient evidence to recommend PBT outside of clinical trials in lung cancer, head and neck cancer, gastro-intestinal malignancies (with the exception of hepatocellular(liver) cancer) and pediatric non-Central Nervous System malignancies. In hepatocellular carcinoma and prostate cancer, there is evidence of the efficacy of PBT but no suggestion that it is superior to photon based approaches. In pediatric CNS malignancies, there is a suggestion from the literature that PBT is superior to photon approaches, but there is currently insufficient data to support a firm recommendation for PBT. In the setting of craniospinal irradiation for pediatric patients, protons appear to offer a dose measuring benefit over photons but more clinical data are needed. In large ocular melanomas and chordomas, we believe that there is evidence for a benefit of PBT over photon approaches. In all fields, however, further clinical research is needed and should be encouraged (ASTRO, 2011).

American College of Radiology (ACR) appropriateness criteria state that the physical characteristics of the proton beam would seem to allow for greater sparing of normal tissues, although there are unique concerns about its use for lung tumors. The small amount of clinical data on its use consists of small single institution series. These data as a whole can be challenging to interpret, as various different techniques have been used by these institutions, making comparisons between studies difficult. Results from larger, prospective, controlled trials that are underway will clarify the role of proton beam and other particle therapies for lung cancer (ACR, 2010).

A Blue Cross Blue Shield technology assessment evaluated health outcomes following proton beam therapy compared to stereotactic body radiotherapy (SBRT) for the management of Proton Beam Radiation Therapy: Medical Policy 12 non-small-cell lung cancer. The report concluded that, overall, evidence is insufficient to permit conclusions about the results of PBT for any stage of non-small-cell lung cancer. All PBT studies are case series, and there are no studies directly comparing proton beam therapy (PBT) and stereotactic body radiotherapy (SBRT). In the absence of randomized, controlled trials, the comparative effectiveness of PBT and SBRT is uncertain (BCBS, 2011).

The only guideline that I found that offers a qualified support is NCCN. The National Comprehensive Cancer Network (NCCN) states that the use of more advanced radiation technologies, such as proton therapy, is appropriate when needed to deliver adequate tumor doses while respecting normal tissue dose constraints (NCCN, 2012).

It is quite clear from limited studies that proton beam is not inferior to other radiotherapy techniques. What has not been proven is that it is superior and that its ability to spare the tissues translates to a better outcome. It makes sense that it should, but in science that would be called a hypothesis that needs to be proven. Because PBT is only available in limited centers and is much more complex and expensive than other tissue sparing radiation therapy techniques, it should still be considered investigational.

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