Radiation Therapy for Metastatic Non-Small Cell Lung Carcinoma of the Right Hip

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1 Angela Kempen June Case Study June 15 th, 2012 Radiation Therapy for Metastatic Non-Small Cell Lung Carcinoma of the Right Hip History of Present Illness: HT is a 66 year-old Caucasian male who was diagnosed with advanced stage lung cancer in April A month later he was diagnosed with Hurthle cell carcinoma of the thyroid. He has received past chemotherapy consistent of carboplatin and taxol with bevacizumab, and most recently pemetrexed. He has been experiencing increasing pain in a known pathologic fracture of the right ilium. Even having his belt on is causing significant pain. He is currently receiving palliative radiation to the low thoracic and lumbar spine and taking weekly Adriamycin. Previous therapy includes radiation to the left neck, left shoulder, L5 and right pelvis. Additionally, his right pelvis is starting to cause him increasing pain inferiorly. He is having pain in his right groin and trouble with weight bearing. He will finish his course of treatment to the low thoracic and lumbar spine, and will then receive a single fraction to the inferior right pelvis area. After radiation treatments are complete, he will be set up with a Medical Oncologist. Past Medical History: The patient suffers from depression. The patient has cardiomyopathy, making it difficult on recent echocardiograms to visualize the heart well. The patient was diagnosed with non-small cell lung cancer in April He was stage IIIB with recurrent malignant left pleural effusions. He was receiving chemotherapy for one and a half years. He was diagnosed with Hurthle cell carcinoma of the thyroid a month later. Additionally, he has an enlarged prostate and received transurethral needle ablation of the prostate. The patient has diabetes mellitus type 2, hypertension, and obstructive sleep apnea. The patient has had previous radiation therapy and chemotherapy. Diagnostic Imaging Studies: The patient received a positron emission tomography/computed tomography (PET/CT) scan from base of skull to mid-thigh. This scan was evaluated and compared to a previous PET/CT scan. Improved metastatic disease involving the right iliac bone and left scapula was found; however, worsening metastatic disease involving the pelvis, spine, right scapula, right proximal humeral head and bilateral proximal femurs was found. Overall findings were compatible with disease progression. X-rays were taken of the pelvis and right lateral hip because of right groin pain and trouble with weight bearing. The findings revealed an osteolytic lesion in the right symphysis and superior pubic ramus consistent with pathologic

2 2 fracture. There may be a fracture through the inferior pubic ramus on the right. A magnetic resonance imaging (MRI) scan cannot be performed due to the presence of his pacemaker. Family History: The patient s father and mother suffered from diabetes type II and heart disease. The father is deceased at age 76 and the mother is deceased at age 80. A paternal grandfather had stomach cancer and is deceased. Social History: The patient is married and resides with his wife. They have three children. The patient is a former smoker who quit five years ago. He rarely uses alcohol and has never used drugs. There are concerns with his sleep patterns. It takes him awhile to get to sleep and then he is up approximately 3-4 times during the night. Medications: The patient uses the following medications: Ascorbic acid, Citalopram, Coenzyme, Dexamethasone, Fluticasone, FreeStyle Lancets, Glucose (DEX4), Ibuprofen, Levitra, Lorazepam, Metformin, Pseudoephedrine, Acidophilus, Amoxapine, Fexofenadine, Glipizide, Metoprolo-XL, Pravastatin and Ramipril. Recommendations: The Radiation Oncologist recommended that the patient receive radiation therapy for management of pain in his right hip. The patient had the toxicities of right pelvic radiation reviewed with him. These included, but not limited to, fatigue, skin reaction and diarrhea. Potential for bowel injury requiring intervention and surgery was discussed. The patient wished to proceed with the palliative radiation therapy treatments for management of his pain. The Plan (Prescription): The plan is for the patient to receive 800 centigray (cgy) in a single fraction to his right hip. Patient Setup/Immobilization: The patient was simulated in the supine position, with a lower VacLoc bag to immobilize his lower body. The same immobilization being used for treatment of his lumbar spine was used for the simulation. A treatment planning computed tomography (TPCT) was completed with 2.5 millimeter (mm) slices through the pelvic region. Anatomical Contouring: The physician referred to the PET scan to contour the gross tumor volume (GTV). I contoured the bladder and rectum. Beam Isocenter/Arrangement: I placed the isocenter for this plan, using the automatic function in the Pinnacle treatment planning system, in the center of the GTV. I placed an anterior beam with 0 degrees on the gantry. The physician then drew blocks around the GTV. I copied and opposed the anterior beam to create a posterior beam with 180 degrees on the gantry, and the physician made some minor adjustments to the block. Treatment Planning: Since the patient had been previously treated to the pelvic region, the physician asked that I place the previous treatment fields onto the treatment plan for the right hip. The previous treatment fields can be viewed in Figure 1. Once I had placed the previous

3 3 fields, the physician made changes to his blocks on the anterior and posterior fields for the hip. He used the same isocenter that was used for the previous fields and brought the Y2 jaw down to -7.5 in order to leave a small gap between the previous and current treatment portals. Figure 2 shows the treatment fields drawn by the physician. I placed a calculation point in the center of the GTV since the isocenter was no longer in the treatment field. I then chose an energy of 10 MV for both beams and calculated the dose. I had hot areas laterally, so I placed a 15 degree wedge on both fields with the heel facing laterally. This can be viewed in Figure 3. I recalculated the dose and optimized by weighting the beams with 52.8% anteriorly and 47.2% posteriorly. I called the physician to evaluate the plan and he approved it at the 100% isodose line. This can be viewed in Figure 4. I then turned on the previous beams, which were treated at 250 cgy per fraction for 15 fractions, and the physician reviewed the plan with cumulative doses. This can be seen in Figure 5. Figure 1: Previously treated fields Figure 2: Treatment fields used for R hip plan (GTV in red)

4 4 Figure 3: 15 degree wedges used APPA to optimize plan Figure 4: Transverse, Sagittal and Coronal slices of Calculation Point

5 5 Figure 4a: Isodose transverse slices Figure 5: Isodose transverse slices for composite of two treatments

6 6 Monitor Unit Check: Monitor unit (MU) calculations were performed to verify that the treatment planning computer was calculating properly. MU check by Oncology Data Systems, version 8.2.0, takes several factors into consideration in order to perform an accurate calculation to determine the monitor units needed for treatment. The MU result is compared to the computer MU calculation. The difference between the two should result in less than 5%, which it did for this plan. Quality Assurance Check: A physicist performed a second check of the treatment plan and monitor unit check. It is critical to have an independent set of eyes look over the plan and additional checks. Conclusion: I chose this plan because of the addition of previous radiation treatment fields. I have never put previous fields onto the treatment planning computer before attempting this plan. I first had to determine the isocenter, and then set correct gantry angles and field sizes, in addition to fabricating the blocks the physician had drawn on the previous fields. I am glad I had the opportunity to work on this plan since some patients, unfortunately, have radiation treatment more than once to an area adjacent to a previously treated area. Figure 6: Dose Volume Histogram