Two Field Adjuvant Radio Therapy Technique Report

Introduction

In an adult female, the breast is located at the anterior surface of the chest, it usually extends from the second rib superiorly to the sixth rib inferiorly and the medial border is at the sternal edge and it reaches to the mid- axillary- line laterally (Ellis, 2010). Each breast is divided into invisible four quadrants as shown in figure 1 (Memorang, 2018). Over the years, the incidence of cancers developing in the upper outer quadrant is much higher than in other quadrants (Bright et al., 2016).

Case background and treatment option

A 47 years old female was presented with a lump in the upper outer quadrant of right breast. The results of the examinations have shown that she is diagnosed with grade three (Macmillan, 2018) invasive ductal carcinoma IDC in the upper outer quadrant of the right breast, ER (estrogen-receptor) positive, PR (progesterone-receptor) positive and HER-2 (human epidermal growth factor) negative. According to the TNM staging system (Hammer et al, 2008) she was diagnosed with stage I breast cancer as has been shown in Table (1) with the size of the tumour being 18mm with no invasion to lymph nodes and no metastasis present.

The treatment decision for this patient was, right breast wide local excision + sentinel node biopsy (2 sentinel nodes were removed). The aim of wide local excision is to remove the tumour with extra margin of normal healthy tissue while improving the cosmetic appearance as possible (Goyal, 2012).

Adjuvant chemotherapy is given post-surgery to reduce the risk of recurrence (Curigliano et al., 2017). She had given 6 cycles of FEC (5 Fluorouracil, Epirubicin and Cyclophosphamide) for a duration of 3 years once every 6 months. To ensure that all tumour cells are eradicated and to reduce the mortality and the risk of recurrence (Coles et al., 2017), she was also prescribed 4005cGy of radiotherapy (RT) in 15 fraction over 3 weeks plus 1200cGy boost to the tumour bed in 4 fractions to the tumour bed (PLACEMENT SITE A, 2017).

Pre-treatment & Planning

I ordered to plan the RT treatment, a computed tomography (CT) scan is performed and in this scan, the patient has to be very well immobilised as the scan position must be the same for every subsequent RT treatment (Fung et al 2011).

Firstly, the patient had to lie first head supine on Posiboard-2 (Placement Site A, 2015) with knee-rest for comfort and stability and the arms have to be above head as elevating the arms will raise the breast superiorly which can provide symmetry as well as reduce the dose to lung and heart (Goldsworthy et al 2011).

After that, a radiopaque marker is put on; reference points (the midsternum (anterior midline) and two lateral markers one on each side), superior and inferior margins of the scanning field and any surgical scars on the breast (Barrett, 2009). The slice sickness of the CT’s is 2mm to produce adequate image quality of target volume and organs at risks (OARs) (PLACEMENT SITE A, 2017), the scanning levels are; angle of mandible superiorly, 5cm inferior to the breast tissue inferiorly to include all ipsilateral to the lungs and the whole beast, lung and heart are included so the dose volume histogram (DVH) can calculate the dose to OARs (Placement Site A, 2014). Then the image could be acquired and permanent tattoos are applied on the midline reference point, right and left lateral reference points and then The CT data exported to treatment planning system (TPS).

Field placement and Target volumes definitions

During pre-treatment, the planner will define the target volumes by outlining the whole breast as the Clinical Target Volume (CTV) with excluding the rib cage, overlying skin and muscles and the excision scar as the aim of the treatment is to treat all glandular tissues of the breast (Placement Site A, 2014). No Gross Target Volume (GTV) is outlined as the tumour is removed surgically. The Planning Target Volume (PTV), is then drown by adding 1.5cm margin around the CTV to account for variations in patient’s position, breast swelling, set-up uncertainty, penumbra and respiration (Barrett, 2009).

OARs are outlined on the virtual simulator and a dose constraint form is achieved as required by the departmental protocols and summarised in Table 2 (Placement Site A, 2016). A maximum Central Lung Distance (CLD) of 2cm on the lateral border of the field is accepted as the superior border should include the entire breast to the level sternal notch and 1.5cm below the breast inferiorly (Placement Site A, 2014).

For the electron boost treatment, the CTV is the tumour bed and the PTV is outlined by adding 1-1.5 margin around the CTV (Placement Site A, 2014). Electron boost reduces local recurrence in breast cancer (Antonini et al., 2007). When both plans are utilised, digitally reconstructed radiographs are printed.

Treatment technique

As the breast size is not large, 6mv photon radiation is chosen for this patient to produce best dose homogeneity to the breast and reduce skin toxicities (Lacey et al., 2007). The dose and fractionations are summarised in Table 3 (Placement Site A, 2017). Intensity Modulated Radiotherapy (IMRT) technique is performed, the gantry angle for the medial beam was 40° to align with the chest wall and 230° for the lateral beam with collimator at 0 ° in both beams (Placement Site A, 2018). The patient had MV image in the first three fractions and then weekly and it was compared to the CT scan to ensure similar patient’s position during treatment delivery (Barrett, 2009). In vivo dosimetry is done in the first fraction using a diode check to ensure that the planned dose is being delivered (Kinhikar et al., 2012).

Patient care

She was informed about the possible side effects which she might experience such as tiredness, fatigue, skin reactions, depression and lymphedema (NICE, 2018). She was advised to avoid robbing of the irradiated when washing up and alsothe application of the Zerobase cream at least two hours before every treatment. The consultant advised her to Maggie’s centre and she said it was useful. Thankfully, she had no serious side effect and only tiredness was what she was suffering from. Annual mammogram will be offered for five years then will be referred to the breast cancer screening programme NHSBSP (NHS, 2015).

References:

• Ellis, H. (2010). Anatomy of the breast. Surgery (Oxford), 28(3), 114–116. https://doi.org/10.1016/j.mpsur.2009.11.003.
• Bright, C., Rea, D., Francis, A., & Feltbower, R. (2016). Comparison of quadrant-specific breast cancer incidence trends in the United States and England between 1975 and 2013. Cancer Epidemiology, 44, 186–194. https://doi.org/10.1016/j.canep.2016.08.019.
• Hammer, C., Fanning, A., & Crowe, J. (2008). Overview of breast cancer staging and surgical treatment options. Cleveland Clinic Journal of Medicine, 75 Suppl 1, S10–6. https://mdedge-files-live.s3.us-east-2.amazonaws.com/files/s3fs-public/issues/articles/content_75_Suppl_1_SI-10.pdf.
• Goyal, A. (2012). Current Trends in Breast Surgery. Indian Journal of Surgical Oncology, 3(4), 287–291. https://doi.org/10.1007/s13193-012-0175-x.
• Curigliano, G., Burstein, H., Winer, E., Gnant, M., Dubsky, P., Loibl, S., … Senn, H. (2017). De-escalating and escalating treatments for early-stage breast cancer: the St. Gallen International Expert Consensus Conference on the Primary Therapy of Early Breast Cancer 2017. Annals of Oncology, 28(8), 1700–1712. https://doi.org/10.1093/annonc/mdx308.
• Coles, C., Griffin, C., Kirby, A., Titley, J., Agrawal, R., Alhasso, A., … Bliss, J. (2017). Partial-breast radiotherapy after breast conservation surgery for patients with early breast cancer (UK IMPORT LOW trial): 5-year results from a multicentre, randomised, controlled, phase 3, non-inferiority trial. The Lancet, 390(10099), 1048–1060. https://doi.org/10.1016/S0140-6736(17)31145-5.
• Fung, W., & Wu, V. (2011). Image-guided radiation therapy using computed tomography in radiotherapy. Journal of Radiotherapy in Practice, 10(2), 121–136. https://doi.org/10.1017/S1460396910000270.
• Antonini, N., Jones, H., Horiot, J., Poortmans, P., Struikmans, H., Den Bogaert, W., … Bartelink, H. (2007). Effect of age and radiation dose on local control after breast conserving treatment: EORTC trial 22881-10882. Radiotherapy and Oncology, 82(3), 265–271. https://doi.org/10.1016/j.radonc.2006.09.014.
• Lacey, C., Gordon, K., & Nalder, C. (2007). Characterisation of 6MV and 10MV superficial build up dosimetry in tangential beam radiography. Journal of Radiotherapy in Practice, 6(4), 229–241. https://doi.org/10.1017/S1460396907006164.
• NICE 2018 https://www.nice.org.uk/guidance/ng101/chapter/Recommendations#complications-of-local-treatment-and-menopausal-symptoms.
• NHS., (2015). Guideline for the Follow Up of Patients Following Treatment for Breast Cancer. [online]. [viewed 26 Feb. 2018].Available from: https://www.uhb.nhs.uk/Downloads/pdf/CancerPbBreastCancerFollowUp.pdf..
• Goldsworthy, S., Sinclair, N., Tremlett, J., Chalmers, A., Francis, M., & Simcock, R. (2011). Abducting both arms improves stability during breast radiotherapy: The Bi Arm study in radiotherapy. Journal of Radiotherapy in Practice, 10(4), 250–259. https://doi.org/10.1017/S1460396910000452.
• Barrett, A. (2009). Practical radiotherapy planning. (4th ed.). CRC/Taylor & Francis.
• Kinhikar, R., Chaudhari, S., Kadam, S., Dhote, D., & Deshpande, D. (2012). Dosimetric validation of new semiconductor diode dosimetry system for intensity modulated radiotherapy. Journal of Cancer Research and Therapeutics, 8(1), 86–90. https://doi.org/10.4103/0973-1482.95180.
• Macmillan, 2018. Staging and grading of breast cancer. https://www.macmillan.org.uk/information-and-support/vulva-cancer/treating/treatment-decisions/understanding-your-diagnosis/staging-and-grading.html.
• Memorang, 2018 Anatomy, Development, & Physiology of the Breast https://www.memorangapp.com/flashcards/151756/Anatomy%2C+Development%2C+%26+Physiology+of+the+Breast+4%2F25/.

Work instructions:

PLACEMENT SITE A, 2017. Radiotherapy for breast malignancies 2, 3, 4 field radiotherapy to the breast/ chest wall, virtual simulation, using a mono-isocentric technique. Doc No; CP 3.004 [Viewed 25 February 2019].

PLACEMENT SITE A, 2016. Breast Dose Constraint Form. Doc No; eFM 14.048. [Viewed 25 February 2019].

PLACEMENT SITE A, 2015. RADIOTHERAPY TO THE BREAST/CHEST WALL (+/- LYMPH NODE DRAINAGE AREAS) USING A MONO-ISOCENTRIC TECHNIQUE. Doc No; WI 13 37. [Viewed 25 February 2019].

PLACEMENT SITE A, 2014. , 3 OR 4 FIELD RADIOTHERAPY TO THE BREAST/CHEST WALL, VIRTUAL SIMULATION, USING A MONO-ISOCENTRIC TECHNIQUE. Doc No; CP 3.004. [Viewed 25 February 2019].

Placement Site A, 2018. Radiotherapy breast field placement and planning on AW. Doc No; WI 12.56. [Viewed 25 February 2019].