Discussion topic:
Is there something clinically that you have learned or read elsewhere that is associated with the material that has been covered to date but isn't found in your lectures or readings?
Discussion post:
One area of study that has only briefly been mentioned in our coursework that I’ve had the opportunity see a lot of in clinic is stereotactic body therapy (SBRT) lung treatment. In a seminar held by one of our physicians we took an in depth look at SBRT lung treament.1 In this lecture I learned that surgery is the gold standard for stage 1 well performing non-small-cell-lung-cancer (NSCLC) patients with a control rate of 97%. However, not all patients are healthy enough to undergo lung surgery so they are referred for SBRT. The control rate for SBRT for NSCLC is 95% compared to the much lower control rate of 50-30% for standard fractionation radiation therapy. One thing I hadn’t considered is that early stage NSCLC lung cancer is almost always an incidental finding. Typically, a patient undergoes testing for another medical issue and early stage lung cancer is identified. This is due to the fact the lungs can function surprisingly well until they are significantly affected. Additionally, NSCLC is slow growing so it is possible to find before it has metastasized. Small-cell-lung-cancer (SCLC) on the other hand is fast growing and much harder to catch at an early stage.1
CT simulation of SBRT patients is an interesting procedure at our clinic. The treatment table is set up with base plate and head rest, and a large stereotactic vac-loc is placed on top of it. The stereo tactic vac-loc is the same as a regular vac-loc in every except for its large width and length. The A breath measuring apparatus is placed on top of the vac-loc and once the patient lies supine with arms up, the breath measuring apparatus is strapped around the patient’s chest. The vac-loc is formed around the patient, the best visual is a giant burrito or hotdog bun. Three separate scans are performed with the patient holding his or her breath and a separate 4D scan is taken with free breathing. In dosimetry the physician reviews a composite of the three breath hold scans and analyses tumor movement. The same analysis is done on the 4D scan and tumor motion is compared between the two studies. Ultimately, one method is chosen and the patient will be treated either with breath hold and gating or with free breathing also gated to measure consistency.
Side effects of SBRT for lung cancer are also favorable compared to surgery. The main advantage is there is no recovery period and patients can enter and leave the clinic from day to day during the course of their treatment with little other interruptions to their life. Long term side effects of SBRT are radiation pneumonitis, scarring to a small volume of lung tissue, risk of rib fracture for laterally located tumors, and risk of mediastinal recurrence after five years. Although surgery is the best option for NSCLC patients SBRT is showing positive results that years ago would not have been possible for non-surgical candidates.
References
1. Rineer, J. Site Specific Treatment Planning: Lung 1. [Physics Residency Lung Seminar]. Orlando, FL: UF Health Cancer Center Physics Residency Program; 2017.
Is there something clinically that you have learned or read elsewhere that is associated with the material that has been covered to date but isn't found in your lectures or readings?
Discussion post:
One area of study that has only briefly been mentioned in our coursework that I’ve had the opportunity see a lot of in clinic is stereotactic body therapy (SBRT) lung treatment. In a seminar held by one of our physicians we took an in depth look at SBRT lung treament.1 In this lecture I learned that surgery is the gold standard for stage 1 well performing non-small-cell-lung-cancer (NSCLC) patients with a control rate of 97%. However, not all patients are healthy enough to undergo lung surgery so they are referred for SBRT. The control rate for SBRT for NSCLC is 95% compared to the much lower control rate of 50-30% for standard fractionation radiation therapy. One thing I hadn’t considered is that early stage NSCLC lung cancer is almost always an incidental finding. Typically, a patient undergoes testing for another medical issue and early stage lung cancer is identified. This is due to the fact the lungs can function surprisingly well until they are significantly affected. Additionally, NSCLC is slow growing so it is possible to find before it has metastasized. Small-cell-lung-cancer (SCLC) on the other hand is fast growing and much harder to catch at an early stage.1
CT simulation of SBRT patients is an interesting procedure at our clinic. The treatment table is set up with base plate and head rest, and a large stereotactic vac-loc is placed on top of it. The stereo tactic vac-loc is the same as a regular vac-loc in every except for its large width and length. The A breath measuring apparatus is placed on top of the vac-loc and once the patient lies supine with arms up, the breath measuring apparatus is strapped around the patient’s chest. The vac-loc is formed around the patient, the best visual is a giant burrito or hotdog bun. Three separate scans are performed with the patient holding his or her breath and a separate 4D scan is taken with free breathing. In dosimetry the physician reviews a composite of the three breath hold scans and analyses tumor movement. The same analysis is done on the 4D scan and tumor motion is compared between the two studies. Ultimately, one method is chosen and the patient will be treated either with breath hold and gating or with free breathing also gated to measure consistency.
Side effects of SBRT for lung cancer are also favorable compared to surgery. The main advantage is there is no recovery period and patients can enter and leave the clinic from day to day during the course of their treatment with little other interruptions to their life. Long term side effects of SBRT are radiation pneumonitis, scarring to a small volume of lung tissue, risk of rib fracture for laterally located tumors, and risk of mediastinal recurrence after five years. Although surgery is the best option for NSCLC patients SBRT is showing positive results that years ago would not have been possible for non-surgical candidates.
References
1. Rineer, J. Site Specific Treatment Planning: Lung 1. [Physics Residency Lung Seminar]. Orlando, FL: UF Health Cancer Center Physics Residency Program; 2017.