Can Helical Tomotherapy be used as a Safe Treatment Alternative for Breast Cancer Patients?

Radiation therapy (RT) has demonstrated strong clinical benefits for patients who present a high relapse risk after breast conserving surgery or radical mastectomy. Unfortunately, the benefits of RT can be offset by its possible impacts on cardiac toxicity and increased risk of death from cardiac events. Additionally, recent radiological and radiotherapy techniques have allowed clinicians to better define target volumes and customize irradiation so that doses to the heart and left coronary artery can be accurately quantified. Alternative treatment positions, such as the lateral and prone positions are also being used. These positions can adapt to the patient’s anatomy and thus better protect the heart and lungs. This paper will report the outcomes for a patient who received breast cancer treatment after her treatment position and technique were optimized for ideal target volume coverage and minimum irradiation to organs at risk (OAR), particularly to the heart and lungs. Citation: Jacob J, Campana F, Chira C, Peurien D, Daveau C, et al. (2012) Can Helical Tomotherapy be used as a Safe Treatment Alternative for Breast Cancer Patients? J Nucl Med Radiat Ther S6:002. doi:10.4172/2155-9619.S6-002


Introduction
Radiation therapy (RT) has demonstrated strong clinical benefits for patients who present a high relapse risk after breast-conserving surgery or radical mastectomy [1]. Unfortunately, the benefits of RT can be offset by its possible impacts on cardiac toxicity and increased risk of death from cardiac events [2][3][4]. However, most trials have split their patients into groups that received either systemic therapy or RT but did not describe the clinical context of these events [3]. Additionally, recent radiological and radiotherapy techniques have allowed clinicians to better define target volumes and customize irradiation so that doses to the heart and left coronary artery [2,5,6] can be accurately quantified. Alternative treatment positions, such as the lateral and prone positions [7,8] are also being used. These positions can adapt to the patient's anatomy and thus better protect the heart and lungs.
The Intensity-Modulated Radiotherapy, delivered using several techniques, has been assessed in breast cancer and presents dosimetric advantages compared to the Three-Dimensional Conformal Radiotherapy, in terms of coverage of the target volumes [9] and of sparing of the organs at risk (OAR) [10]. By patients presenting difficult target volumes due to their anatomy or bilateral breast treatment, the Helical Tomotherapy (HT) seems to provide promising dosimetric results with an acceptable clinical tolerance [11]. This paper will report the outcomes for a patient who received breast cancer treatment using HT for a tumor localized at the inner edge. Her treatment position and technique were optimized for ideal target volume coverage and minimum irradiation to the OAR, particularly to the heart and lungs.

Patient's Presentation
A 59-year-old female patient underwent breast-conserving surgery and axillary lymph node dissection for infiltrating ductal carcinoma (IDC) of the lower inner quadrant of the left breast (pT2pN0M0). The 28-mm lesion was grade II, estrogen-receptor positive, progesterone-receptor negative, and HER2-negative. There was no lympho-vascular involvement (LVI) and the surgical margins and the nine resected axillary lymph nodes were free of disease. However, the patient refused chemotherapy and was thus referred to the Department of Radiation Oncology at Institut Curie. The multidisciplinary clinics decided to deliver chemotherapy followed by radiotherapy to the whole breast with a boost to the tumor bed, followed by an hormonotherapy using aromatase inhibitors. Also, due to the internal position and the size of the treated lesion [12,13], the internal mammary (IMN) and supra-clavicular nodes (SCN) required irradiation. The target volumes and OAR were then delineated on the planning CT scan in a treatment position as previously reported [14,15]. The patient refused the chemotherapy and has been treated by radiotherapy followed by letrosole.
Dosimetry was first assessed using Institut Curie's field-in-field technique [16] with the patient in the supine position. However, because the tangential fields included a maximal heart distance (MHD) of 2.6 cm and a central lung distance (CLD) of 3.1 cm, the patient's radiation oncologist did not approve the plan (Figure 1). A new CT scan in the lateral isocentric position was thus taken and a new dosimetric plan was completed ( Figure 2). Although this plan resulted in low doses to the heart and lungs, the radiation oncologist again refused it due to suboptimal coverage of the tumor bed volume and surgical clips area.
The patient's case was thus discussed at Institut Curie's weekly radiotherapy meeting, and Helical TomoTherapy ® (HT) (Accuray Incorporated, Sunnyvale, CA, USA) was suggested and the dosimetry was realized using Tomotherapy Planning System. When the dosimetric study for HT was analyzed (Figure 3), it became clear that HT could deliver optimal coverage to the planning target volumes (Table 1 and 2) while also providing acceptable doses to the patient's heart and lungs (Table 3). Using a previously reported fractionation scheme [17], the integrated boost was then delivered to the tumor bed. Treatment-related toxicity was scored using the Common Terminology Criteria for Adverse Events (v3. 2006). The patient experienced acute grade 1 skin toxicity.
Currently, one year after the Tomotherapy treatment, there is no late toxicity, the patient is still under letrozole and she is regularly followed up.

Discussion and Conclusions
This case illustrates how to customize radiation treatment and decrease the probability of long-term adverse effects through correct patient position, treatment planning, and delivery. Additionally, newly available treatment techniques and modalities allow breast cancer radiotherapy to adapt to a patient's anatomy, deliver optimal coverage to treatment volumes, and minimize dosage to OAR. HT also proved to be a better option for this patient than 3D conformal radiotherapy with the field-in-field technique or the lateral decubitus position. Finally, this CLD CLD Figure 1: Tangential beam set-up and dose distribution using Institut Curie's "field-in-field" technique. The Central Lung Distance (CLD) is mentioned by the green arrow and the Maximal Heart Distance by the red one.   3D-CRT: three-dimensional conformal radiotherapy; HT: Helical tomotherapy Table 1: Delivered relative doses to 95% of the planning target volume.  [17][18][19]. To confirm these dosimetric results, however, prospective studies with a thorough clinical description of patient status, especially cardiac disease risks, are needed [20]. This clinical observation is an example that the early breast cancer treatment becomes highly performant and the radiotherapy tailoring is currently a part of the everyday routine practice.