Postoperative proton radiotherapy for localized and locoregional breast cancer: potential for clinically relevant improvements?
ABSTRACT To study the potential reduction of dose to organs at risk (OARs) with intensity-modulated proton radiotherapy (IMPT) compared with intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3D-CRT) photon radiotherapy for left-sided breast cancer patients.
Comparative treatment-planning was performed using planning computed tomography scans of 20 left-sided breast cancer patients. For each patient, three increasingly complex locoregional volumes (planning target volumes [PTVs]) were defined: whole breast (WB) or chest wall (CW) = (PTV1), WB/CW plus medial-supraclavicular (MSC), lateral-supraclavicular (LSC), and level III axillary (AxIII) nodes = (PTV2) and WB/CW+MSC+LSC+AxIII plus internal mammary chain = (PTV3). For each patient, 3D-CRT, IMRT, and IMPT plans were optimized for PTV coverage. Dose to OARs was compared while maintaining target coverage.
All the techniques met the required PTV coverage except the 3D-CRT plans for PTV3-scenario. All 3D-CRT plans for PTV3 exceeded left-lung V20. IMPT vs. 3D-CRT: significant dose reductions were observed for all OARs using IMPT for all PTVs. IMPT vs. IMRT: For PTV2 and PTV3, low (V5) left lung and cardiac doses were reduced by a factor >2.5, and cardiac doses (V22.5) were by a factor of >20 lower with IMPT compared with IMRT.
When complex-target irradiation is needed, 3D-CRT often compromises the target coverage and increases the dose to OARs; IMRT can provide better results but will increase the integral dose. The benefit of IMPT is based on improved target coverage and reduction of low doses to OARs, potentially reducing the risk of late-toxicity. These results indicate a potential role of proton-radiotherapy for extended locoregional irradiation in left breast cancer.
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ABSTRACT: Proton therapy is associated with significant benefit in terms of normal tissue sparing and potential radiation dose escalation for many patients with malignant diseases. Due to recognition of these qualities, the availability of this technology is increasing rapidly, both through increased availability of large centers, and with the possibility of smaller, lower cost proton therapy centers. Such expansion is associated with increased opportunity to provide this beneficial technology to larger numbers of patients; however, the importance of careful treatment planning and delivery, deliberate patient selection, rigorous scientific investigation including comparison to other technologies when possible, and mindfulness of ethical issues and cost effectiveness must not be forgotten. The obligation to move forward responsibly rests on the shoulders of radiation oncologists around the world. In this article, we discuss current use of proton therapy worldwide, as well as many of the factors that must be taken into account during rapid expansion of this exciting technology.Frontiers in Oncology 09/2011; 1:24. DOI:10.3389/fonc.2011.00024
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ABSTRACT: To assess the factors affecting the incidence of radiation-induced dermatitis in breast cancer patients treated with adjuvant 3 D conformal radiotherapy by the analysis of dosimetry and topical treatments. Between September 2002 and July 2009, 158 breast cancer patients were treated with adjuvant 3 D conformal radiotherapy after undergoing surgery. Before November 2006, 90 patients were subjected to therapeutic skin care group and topical corticosteroid therapy was used for acute radiation dermatitis. Thereafter, 68 patients received prophylactic topical therapy from the beginning of radiotherapy. The two groups did not differ significantly in respect of clinical and treatment factors. Furthermore, the possible mechanisms responsible for the effects of topical treatment on radiation-induced dermatitis were investigated in vivo. The incidence of radiation-induced moist desquamation was 23% across 158 patients. Higher volume receiving 107% of prescribed dose within PTV (PTV-V107%; >28.6%) and volume receiving 110% of prescribed dose within treated volume (TV-V110%; > 5.13%), and no prophylactic topical therapy for irradiated skin, were associated with higher incidence of acute radiation dermatitis. The protective effect of prophylactic topical treatment was more pronounced in patients with TV-V110% > 5.13%. Furthermore, using irradiated mice, we demonstrated that topical steroid cream significantly attenuated irradiation-induced inflammation, causing a decrease in expression of inflammatory cytokines and TGF-beta 1. TV-V110% > 5.13% may be an important predictor for radiation induced dermatitis. Prophylactic topical treatment for irradiated skin can significantly improve the tolerance of skin to adjuvant radiotherapy, especially for patients with higher TV-V110%.BMC Cancer 09/2010; 10(1):508. DOI:10.1186/1471-2407-10-508
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ABSTRACT: With the introduction of new biologically based imaging possibilities, a higher degree of individualisation and adaptation of radiotherapy will be possible. Better knowledge of the biology of the target and its sub-volumes will enable dose prescriptions tailored to the individual patients, tissues and sub-volumes. Repeated imaging during the course of treatment will in addition enable adaptation of the treatment to cope with anatomical, as well as biological changes of the patient and of the target tissues. To translate these bright future perspectives into significant improvements in clinical outcome, advanced tools to tailor the physical dose distributions are needed. The most conformal radiotherapy technique known to mankind and clinically available today is proton therapy; in particular Intensity Modulated Proton Therapy (IMPT) with active spot scanning can not only tailor the dose to the desired target, but also effectively avoid sensitive structures in the proximity of the target to a degree far better than other conformal techniques such as Intensity Modulated Radiotherapy with photons (IMRT). The development of IMPT is now mature enough for clinical introduction on a broad scale. Proton therapy is still more expensive than conventional radiotherapy, but with the present rapid increase in the number of proton facilities worldwide and new initiatives to improve efficiency, the difference in affordability will continue to decrease and in comparison with the benefits, soon diminish even further. Contrary to what is sometimes claimed, the demands for better physical dose distributions and better avoidance of non-target tissue, has never been higher. Prolonged expected survival in many groups of patients emphasises the need to reduce late toxicities. The success of concomitant systemic therapies, with their tendency to cause higher morbidity stresses even further the increased need for subtle dose-sculpting methodologies and tools. There is no contradiction between striving for better physical dose distributions and a more biologically based approach. On the contrary, physical dose distributions are the tools to which achieve a treatment that can meet the biological demands.Acta oncologica (Stockholm, Sweden) 10/2010; 49(7):1124-31. DOI:10.3109/0284186X.2010.498436