Ductal Carcinoma Case Study

Presenting Symptoms, Preliminary investigations and Results

The patient presented with a self-detected 23mm grade 2 ductal carcinoma involving the right upper quadrant of the right. The patient performs regular breast self-examination(BSE) to detect any lump before advanced symptoms manifest. Other symptoms included nipple discharge or retraction, skin changes, alteration in breast contour, lymphadenopathy, mammographic abnormality and distant metastasis. Subsequently, a core biopsy has been done to make a definitive diagnosis, confirmed that a ductal carcinoma with surrounding DCIS (Ductal carcinoma in Situ). She underwent a wide local excision and a sentinel lymph node biopsy. It revealed a 23mm mixed DCIS and ductal carcinoma with grade 2 histology and the sentinel lymph node was negative. The tumour was oestrogen and progesterone receptor positive and non-amplified for HER-2. There was no evidence of lymphovascular invasion. The patient has no family history of breast cancer.

Management Statement and Radiation Treatment Prescription

The common disease management options for breast cancer are surgery, chemotherapy, endocrine

therapy and radiotherapy.
The doctor and patient had a lengthy discussion about adjuvant treatment and the decision is made based on the balance that there is a survival advantage with such a relatively large tumour area, with grade 2 histology, with at least four cycles of chemotherapy. The overall management for the patient include a wide-local excision serving both local control and diagnosis purpose. Then, by receiving adjuvant chemo-radiotherapy, systemic control and local control can be achieved. 4 cycles of chemotherapy using Docetaxel and Cyclophosphamide is likely to increase 15 years survival rate by 10% and decrease recurrence rate.(CTSU, 2005) Radiotherapy of a dose of 42.5Gy in 16 fractions, 2.65Gy/fx followed by a boost to the tumour bed of a further 10Gy in 4 fractions 2.5Gy/fx is prescribed to locally control the recurrence rate and the risk of spread by direct extension. Radiobiologic principles dictated that, with the same amount of effective biological dose, radiation delivered in more rapid treatment schedule has the advantage of more effective in controlling tumour recurrence as comparison to standard regime.(Sartor & Tepper, 2002). The potential drawback being the extensive toxicity. However, A studies conducted by Timothy et al. reported that there is no significant difference in short and long term toxicity for radiation therapy in breast cancer.(T. J. Whelan et al., 2010)

Planning Procedures

Pre-simulation planning
Prior to the CT simulation, the leading RT who are assigned to plan treatment got a CT booking form which included information about patient details, prescription, site(s), chemotherapy, other scan fusion, ready for care date, previous treatment and special requirements. Further, a history read up is required to gain full understanding. RT verified if the details on the booking form matches the history. For this patient, the chemotherapy finishing date needs to match the treatment starting date as radiation treatment should be at least 3 week after the entire course of chemotherapy finished. If any doubt or any incorrect documentation is found, contact the doctor to clarify before taking the scan. Most importantly, check if the patient and RO have signed a consent form.

Room preparation
Daily CT scanner QA is performed at the start of the business day. CT warn up to be performed if the scanner has not been used in an hour. Prepare the wire markers and tapes. Attach stabilisation equipment on the bed.
In this department, wire markers are used instead of ball bearings are used to delineate the interested point on the skin, because wire markers are made of copper which does not produce metal artefact, therefore, an accurate dose calculation can be acquired.

Patient education
Before the scan proceeds, sit down with the patient to have an information section about what was about to happen during the scan. The main purpose is to eliminate any query about the procedure and build rapport. The check points in the session as the following: identify the patient, explain why and how the scan will be taken, mention the positioning and stabilisation, check if the patient has no issue holding her arms up, ask permission to put on tattoos and acquire preferences for treatment time.

Positioning and marking
The patient is identified again with the presence of both leading and secondary RT.
The patient is set-up to supine, lift-up on breast board, arms up. The stabilisation equipment used are breast board and kneefix. The first purpose of breast board is to tilt the chest upward to a horizontal sternum position, so as to align the lung contour to horizontal to the ground. Thus, the volume of lung involved in the field is minimized. The second purpose of breast board is to record and support the arms up position; the aim for arms up is to move the arms out of the field to improve coverage. Kneefix is placed under the knees to relief the muscle tension under the lower back region. To reproduce the position in CT scan, stretch measurements are taken including the distance between tip of elbow.
The RO came in to mark the border of breast tissue, upper level, lower level and the extension of scar tissue (boost) to be treated. Wires are placed onto these markings in order for it to visible under the scan.
After the patient is properly setup, baseline determined using the patient’s bony landmark: ML = SN->PRP(10cm inf of SN)->TOX; HRL = POX/BOX-> Lat Tattoo at PRP level->Lat Tattoo at TOX level.
Inform the patient to stay still and breath normally before taking the scan.

CT data acquisition
Register the patient’s information and double check with the other RT. Acquire scan according to the scan site and position so that the scanner can deploy optimal kV and mAs to reduce unnecessary exposure. The slice thickness is default to 2mm, therefore, the start and end parameters must be divisible by 2. Number of slice depends on the length of scan. To account for scatters happens around the volume of interest, the scan must be at least more than 3cm sup and inf of target area.

Contouring
Patient volume is contoured for dose calculation;
Wire is contoured for RO to mark breast and boost volume and PTV and CTV;
Ipsilateral lung and liver are for OAR dose evaluation;

QA
Since liver is not involved inside the field, there is only lung to be evaluated in terms of DVH. And the dose constraint is V20<20.

Treatment Procedures

Pre-treatment
Before the treatment course commences, RTs ran pre-treatment check. The purpose of this check is to verify if the data sent from XiO to ARIA is correct and without missing data. MLCs are also visually checked to ensure that correct data transfer has occurred and have matched to the Field Aperture.

First treatment
First treatment is the longest in the entire treatment course due to the initial measurements. The patient is set-up as per instructed using index couch and indexed breast board. Field borders are marked with texta. The bed is raised to HRL to check levelling. The bed is positioned on CA tattoo and moved 10cm superior to check arm reference line. Then drop the couch to the isocentre SSD and move laterally to isocentre. Gantry is rotated to the medial tangential field to check matching of shielding parameters. If the medial edge does not match the marking, the couch vertical is adjust to achieve a direct match. As the tolerance on couch height is 0.8cm, the position of the isocentre relative to post edge should not change significantly if this adjustment is made. Once aligned perfectly with the required shielding position, the gantry is rotated to the opposing lateral field.

If the patient rotation is correct and patient anatomy has not changed markedly from day to day, the lateral field is expected to match to the skin marks without adjustment. However, if the beam post edge entrance point falls anterior or posterior to the required position, an adjustment of the couch height and gantry position is required. This double shift on the lateral enables the beam post edge entrance points on the medial to be re-established.

On the first day, couch parameters are acquired; the tolerance for lateral and longitudinal are 1cm. EPI images are taken on first day; otherwise a medial setup field image is taken post-treatment.

Imaging protocol
In this department, Cine image on medial tangent field is taken on day 1, then portal image on medial and lateral field every 3rd fraction. Cine image is a series of MV infield images being taken every 2 MU. This set of image is used to evaluate the breast tissue coverage and lung involvement. Breast tissue should completely fall under the treatment field. There should be at least 1cm of lung tissue involves in the field. If they are out of tolerance, repeat on the 2nd day; if it is out again, it should be reviewed by the charge or RO to decide if the treatment should be ceased. The same parameters are evaluated for the portal images. The reason for doing a Cine image on the 1st day is to observe the breathing behaviour of the patient. If the cine image matching is under tolerance on the first day, which the patient is likely to be most anxious, the patient’s breathing would proved not to cause issues at any point of time during a treatment beam is delivering.

SSD contour check
SSD reading is checked first then every 5 fractions in every 30 degrees increments, which means 0, 330. 300, 270. If the reading is out of 1cm tolerance, the SSD is repeated on the next day. If it is still not within +/-1cm, the RTs have to investigate the reason, if the breast is swelling extensively or patient losses weight, the charge and RO needs to make a judgment call for whether or not to replan, or even cease the treatment.

Field modifier
MLCs wraps around the breast tissue to shield lung. It also used in the subfields to shield out hotspot. Dynamic wedges are implemented to increase dose posteriorly in order to overcome patient’s contour.

Rationale of Technique

a) Treatment Prescription – Why is it appropriate? Discuss the fractionation schedule?
According to various of literature, the standard radical dose prescription for effective loco-regional control in post-operative radiation therapy is ranged from 46-50Gy of total dose to tumour bed and 10Gy boost to scar tissue delivered in 1.8-2 Gy per fraction.(Das, Cheng, Fein, & Fowble, 1997) However, the dose prescription for this patient is different from the standard regime by having less total dose and higher dose per fraction. The reason for the regime is that radiobiologic model dictated that a larger dose per fraction (hypofractionation) allow the whole course of treatment be delivered in a shorter period of time (dose acceleration therapy) is just as effective as the standard regime.(Fowler, 1989) A shorter course of treatment has the advantage of being convenient for patients. Example for this patient, she lives 1.5 hour away from the hospital, less treatment fractions means she can reduce cost on patrol, parking fee and, most importantly, increase quality of life as she does not have to spend 3 hours on travelling every day. In an oncological centre point of view, less treatment means less resource-intensive. By fit in more patients in a fix period of time, the waiting list is shorten, thus, it is more beneficial to the general health care service receiver.

The main consideration of hypofractionation in the radiotherapy community is the toxicity given to the normal tissue and organ at risk due to decrease in recovery time. Studies conducted by Timothy et al. reported that the difference between both regimens is acceptable. The result of the study stated that 5 years local recurrence free survival has only 0.6% difference.(T. Whelan et al., 2002) 10 years local recurrence only has the diffence of 0.5%.(T. J. Whelan et al., 2010) It is safe to conclude that the advantages of hypofractionation regime definitely outweigh the disadvantages.

b) Target Volume and Organs at Risk– What is contained inside each ICRU volume? What are the organs at risk? How is dose to these evaluated? How are these avoided?
The target volumes are CTV and PTV. CTV included the tumour bed. PTV included 0.5cm margin around breast tissue and tumour bed. Organs at risk for right breast cancer patients are ipsilateral lung and liver. These OARs are evaluated by DVH. The most meaningful dose constraint used in this clinical centre is V20<20. In literatures, the dose constraint is often found to be V30<15, V20<25, Mean<10. By considering the field arrangement and dose distribution, liver receives no significant amount of dose is contoured just for billing purpose. The ipsilateral lung involvement is approved by the RO, therefore, it is unlikely that it will receive unacceptably high dose. Nevertheless, MLCs and Jaws can be adjusted to shield out excess dose.

c) Technique – Why is the technique suitable?
The technique used is a simple tangential field arrangement. The posterior edge of medial field and lateral field are matched to an axis to avoid unnecessary dose caused by divergence. This field arrangement is the most effective mean to maximize the dose deposit in breast tissue, while not irradiating other normal tissues.

d) Dosimetry – Provide a qualitative and quantitative analysis of the dosimetry.
Dose objective suggested by ICRU62 is +7/-5 of prescribed dose.(Landberg, Chavaudra, & Dobbs, 1999) Qualitatively, 95% of dose covers the entire breast tissue. According to ICRU50,hotspot is only clinically meaningful if it is larger than 1.5mm minimum diameter.(Jones, 1994) With the implementation of 2 subfields on both lateral and medial field, there was no hotspot appeared in the plan. For electron boost and overall, both are having decent 90% cover and no hotspot is found.
Quantitatively, ipsilateral lung is under dose constraint.

Technical Aspect

Deep Inspiration Breath Hold(DIBH) for breast cancer
DIBH is a technique that effectively and reproducibly decrease radiation dose to the heart during left breast radiotherapy.

Although the patient in this case study is having a right breast treatment, DIBH is an interesting topic to discuss because of its convinence of not have to utilize any intricate and expensive equipment. Methods to reduce long term side effects gradually become increasingly important due to the improvements in survival rate. Today, there are two main gating techniques being used clinically. The first requires a digital spirometer to breathe through it; the second technique is breath-hold technique perform on respiratory gating system. Both technique are effective in reducing side effects, however, they require expensive equipment and high maintenance cost that prevent tight budget department from adapting

them.

DIBH provide an alternative to those methods without the heavy cost. The principle of DIBH is by inhaling deeply, the lungs and rib cage expand. Lung tissue superior to the heart increase in volume, subsequently push the heart posteriorly. This treatment position allows for a field arrangement that completely avoid giving any dose to the heart can be achieved. The theoretical advantage is two fold, firstly is to dramatically decrease heart dose; secondly, by only treating with fully inhaled position, the anatomy becomes more constant, thus, less motion error has to be take into account. Because the margin of the volume could be reduced, dose distribution would potentially become more conformal. The basic execution is to educate the patient to hold their breath for 20s. During the scan, mark and measure the intersection of reference lines on deep inspiration and expiration position. Scan only in deep inspiration. During treatment, patient is aligned to deep inhaled position. Then patient is reminded to perform deep inspiration just before the beam is turned on, meanwhile, RTs visually verify the field edge through monitor.

Multiple studies conducted to determine the effectiveness of this technique. The introduction of DIBH entirely avoid heart irradiation in 1/3 of the total samples and median hear volume receiving >50Gy of prescription dose was reduced by 7%.(Pedersen, Korreman, Nyström, & Specht, 2004; Remouchamps et al., 2003; Sixel, Aznar, & Ung, 2001) Despite the excellent potential of dosimetry, it inhere some limitations. Firstly, DIBH require voluntary breathing, which is in turn not suitable for patients having difficulty maintaining a consistent breathing pattern. Secondly, the patient needs to be able to follow verbal instructions and education, therefore, DIBH is not suitable for cognitive impaired patients.

The patient in this case study did not implement this technique mainly because DIBH technique in this department does not commence using until next year. Nevertheless, if this technique would have been used, the ipsilateral lung volume receive would have been decreased by 7-17%.(Pedersen et al., 2004)

Patient Care, Radiation Therapy reactions and Approaches to reduce reactions

The patient is a kind middle aged women who are quite talkative. She is relatively obedient and cooperative. The questions she asked was all closely related to her treatment procedure, for example “why do I have to take another CT scan? I have already taken one on March,” which was indeed a valid question. Sometime, she was too keen or excited to help the RTs, which occasionally altered the positioning. It may cause the RTs to feel irritated at time, but that was just the patient being enthusiastic and optimistic about the treatment. The specific information we have to deliver is to let her stay heavy and relax her body. I had a good time working with her, because she was being extra supportive from the moment she noticed I am a student. We establish rapport quickly and maintain it extremely well throughout the course of her treatment.

The other treatment professionals involved in the her care pathways including but not limited to the following professions:(Cho, 2014)
Medical oncologist: Prescribes and coordinates chemotherapy, hormone therapy and targeted drug therapies;
Radiation oncologist: Prescribes and coordinates radiotherapy;
Surgeon: Specialises in surgery and performs biopsies;
Nurses: Specialist nurses who are trained in radiation treatment care and provide information and support through all stages of treatment and ongoing care;
Occupational therapist and Physiotherapist: assist in restoring range of movement after surgery and radiation therapy.

For the given treatment site and dosimetry, the potential reaction are fatigue, loss of appetite, skin changes, lymphedema, Brachial plexopathy, Myelopathy and Osteoradionecrosis.

Skin change involves several severity of skin and subcutaneous tissue break down, from mild to severe: erythema, dry desquamation, moist desquamation and skin necrosis. The exact onset time is different depends on patient’s physiology, however, the reaction can normally be observed after 2 weeks of treatment. It was quicker for this patient due to the hypofractionation regime. Patient would first observe the redness and inflammation on the skin, sometime shiny. Then, the patient is likely to complain about itchiness, burning and uncomfortable. By the end of treatment course, patients who are less tolerable to radiation would undergo breaking down of skin, which require dressing to ensure comfort and avoid infection the skin. Nevertheless, the principle of skin reaction is to keep it moist, minimize irritation and increase comfort, therefore, Sorbolene cream is normally provided to the patient to put on the treatment area. Other alternative skin moisturisers are encouraged as long as it is mild, no irritative additions, colourless and odourless.

Regarding to fatigue, patients are encouraged to do mild exercise and consume high energy food to increase energy level. If the patient has loss her appetite and loss weight, she will be referred to the dietician who would recommend meal menu or prescribe weight gain supplement such as Ensure nutrition shake to help the patent maintain weight. (3229 words)