Radiotherapy vs. Cystectomy for Treatment of Muscle Invasive Bladder Cancer in Very Elderly Patients

PURPOSE/OBJECTIVE(S)

Radical cystectomy (RC) has long remained the principal treatment of muscle invasive bladder cancer (MIBC). It is, however, associated with significant morbidity, long recovery, and reported worse overall and cancer specific survival, particularly for the very elderly (age > = 80). Bladder preservation with transurethral resection of bladder tumor (TURBT) followed by radiotherapy (RT) +/- concurrent chemotherapy (ChT) is regarded as a curative-intent alternative to RC in well-selected patients. The optimal treatment strategy remains unclear in very elderly patients. We hypothesize that outcomes following RT vs RC are clinically equivalent for treatment of MIBC in very elderly patients.

MATERIALS/METHODS

Patients > = 80 years old with T2-T4 N0-N1 bladder cancer treated definitively with RT versus RC were included. Exclusion criteria included history of pelvic RT, prior cystectomy, or palliative treatment intent. Clinicopathologic and treatment-related details, as well as clinical outcomes and toxicities were retrospectively abstracted. Kaplan-Meier analyses were performed.

RESULTS

At a median follow-up of 17 months (range 0.25-190), 47 patients received RT vs 83 patients who underwent RC with median age of 86 years (80-97) vs 83 years (range 80-91) (p<0.01), respectively. Median Charlson Comorbidity Index was similar between groups (p = 0.35) with median 7 for both cohorts, predicting 0% estimated 10y survival. Most patients had cT2 tumors (91% vs 99%, p = 0.06), cN0 nodal status (96% vs 100%, p = 0.06), and urothelial carcinoma histology (79% vs 90%, p = 0.22). Most RT patients received concurrent ChT (90%) and a minority of RC patients received neoadjuvant ChT (16%). 70% of RT pts had complete TURBTs prior to RT. Common RT regimens were 50-55 Gy in 20-25 fractions or 60-64.8 Gy in 30-36 fractions, using IMRT (89%) or 3D conformal (11%) technique. Overall survival for RT vs RC at 1- and 2- years was 79% vs 85% and 57% and 69%, respectively (p = 0.20). Locoregional control at 1- and 2-years was 73% vs 70% and 63% vs 66% (p = 0.59), respectively. Progression free survival at 1- and 2-years was 69% vs 66% and 52% vs 54% (p = 0.75), respectively. No RT patients went on to receive salvage cystectomy. Treatment complications are listed in Table 1; the Clavien Dindo classification system was used to describe acute surgical complications of RC and the Common Terminology Criteria for Adverse Events (CTCAE) Dictionary v5.0 was used for acute and late toxicity of RT.

CONCLUSION

In the very elderly, RT (with or without concurrent ChT) offers survival and locoregional control rates comparable to RC, with a favorable side effect profile. RT should be offered for definitive management of non-metastatic MIBC as an alternative to RC in selected, well- informed, and compliant very elderly patients.

The use of babosa (Aloe vera) in treating burns: a literature review

Alo vera is a centenary remedy use for minor wounds and burns, but its mechanism of wound healing has not been know since. This article will evaluate and gather evidence of the effectiveness and safety of the use of aloe vera in the treatment of burns. A systematic review was carried out on the databases: MEDLINE, LILACS, DECS, SCIELO, in the last 7 years, with the descriptors: "Aloe", "Burns" and "treatment". 16 articles were found. After using the exclusion criteria; research in non-humans and literature review; 5 articles were selected. The article Teplick et al. (2018) performed an in vitro clinical experiment in A. Vera solution, and demonstrated that there was proliferation and cell migration of human skin fibroblasts and keratinocytes, in addition to being protective in the death of keratonocytes. That is, it accelerates the healing of wounds. Muangman et al. (2016), evaluated 50 patients with 20% of the total body surface area burned with second-degree burns, between 18-60 years old, with half of the group receiving gauze dressings with soft paraffin containing 0.5% chlorhexidine acetate and the other half receiving polyester dressings containing extracts of medicinal plants mainly Aloe Vera. It had positive results, a higher healing speed and shorter hospital stay compared to the control group. Hwang et al. (2015) investigated the antioxidant effects of different extracts from 2,4,6,8,12 months of Aloe Vera. And the 6-month concentrated extract of 0.25 mg / mL had a higher content of flavonoids (9.750 mg catechin equivalent / g extract) and polyphenols (23.375 mg gallic acid equivalent / g extract) and the greater ferric reducing antioxidant power (0.047 mM equivalent ferrous sulfate / mg extract), that is, greater potential for free radical scavenging and also a protective effect against oxidative stress induced by tert-butyl hydroperoxide (t-BHP), suggesting evidence of a bioactive potential of A. vera . However, in the article Kolacz et al. (2014) suggested as an alternative treatment the use of Aloe Vera dressing in combination with honey, lanolin, olive oil, wheat germ oil, marshmallow root, wormwood, comfrey root, white oak bark, lobelia inflata, glycerin vegetable oil, beeswax and myrrh, without obtaining significant and conclusive results that would allow the conventional treatment of burns to be subsidized. Finally, in the article by Zurita and Gallegos (2017), it carried out a descriptive cross-sectional study with 321 people, both sexes between 17-76 years of age, of an inductive nature, exploring the experience of this population and their behavioral attitudes regarding the treatment of dermatoses. Aloe vera had 13.8% cited by individuals in the treatment of acne and 33.6% in the treatment of burns. Even with evidence that suggests the efficacy in the treatment of burns with the use of Aloe Vera extract, further clinical trials with larger sample space on the use of Aloe vera dressings in medium burns are suggested for further conclusions.

Organ Doses Associated with Partial-Body Irradiation with 2.5% Bone Marrow Sparing of the Non-Human Primate: A Retrospective Study

A partial-body irradiation model with approximately 2.5% bone marrow sparing (PBI/BM2.5) was established to determine the radiation dose-response relationships for the prolonged and delayed multi-organ effects of acute radiation exposure. Historically, doses reported to the entire body were assumed to be equal to the prescribed dose at some defined calculation point, and the dose-response relationship for multi-organ injury has been defined relative to the prescribed dose being delivered at this point, e.g., to a point at mid-depth at the level of the xiphoid of the non-human primate (NHP). In this retrospective-dose study, the true distribution of dose within the major organs of the NHP was evaluated, and these doses were related to that at the traditional dose-prescription point. Male rhesus macaques were exposed using the PBI/BM2.5 protocol to a prescribed dose of 10 Gy using 6-MV linear accelerator photons at a rate of 0.80 Gy/min. Point and organ doses were calculated for each NHP from computed tomography (CT) scans using heterogeneous density data. The prescribed dose of 10.0 Gy to a point at midline tissue assuming homogeneous media resulted in 10.28 Gy delivered to the prescription point when calculated using the heterogeneous CT volume of the NHP. Respective mean organ doses to the volumes of nine organs, including the heart, lung, bowel and kidney, were computed. With modern treatment planning systems, utilizing a three-dimensional reconstruction of the NHP's CT images to account for the variations in body shape and size, and using density corrections for each of the tissue types, bone, water, muscle and air, accurate determination of the differences in dose to the NHP can be achieved. Dose and volume statistics can be ascertained for any body structure or organ that has been defined using contouring tools in the planning system. Analysis of the dose delivered to critical organs relative to the total-body target dose will permit a more definitive analysis of organ-specific effects and their respective influence in multiple organ injury.

SU-E-T-403: Delivery Efficiency of StereoArc Stereotactic Body Radiotherapy (SBRT)

PURPOSE

Traditional SBRT employs approximately 10 static beams with up to 20 Gy per fraction, requiring lengthy treatments which can be difficult for patients to tolerate, increasing the risk of movement, and causing discrepancies in the reproducibility of the breathing cycle. Commercial VMAT systems offer shorter treatment times with modulated beams; however, modulation is often not necessary or desired for small fields. Conformai arc therapy offers efficient beam delivery, but with only one aperture shape and constant beam weighting over all gantry angles. This study evaluates the efficiency of a new SBRT delivery Method: a conformai arc with multiple aperture shapes and variable dose rate.

METHODS

Three clinical SBRT cases were chosen for this study. Each static field was converted into an arc segment to create a StereoArc plan. Gantry angle ranges were determined from the clinical monitor units, with the MU/degree chosen to maximize the dose rate. All segments were merged into a single arc with variable dose rate. Dose distributions from the StereoArc plans were compared to the clinical static field plans using Pinnacle. Delivery times were compared between the static SBRT plans, both with and without Beam Automation, and equivalent StereoArc plans. All plans were delivered on a Varian TrueBeam using a dose rate of 1000 MU/min.

RESULTS

Dose differences between StereoArc and static plans were minimal. Delivery times for the static plans were 5-8 minutes, while delivery time with StereoArc was less than 3 minutes for all cases, which was equivalent to delivering the static plans with Beam Automation.

CONCLUSIONS

Delivery efficiency was improved up to 60%: from 8 minutes for static fields, to less than 3 minutes for StereoArc. StereoArc appears to be both an effective and efficient way of delivering SBRT for centers not wishing to modulate SBRT and without access to Beam Automation. This study is partially supported by NIH grant 1R01CA133539-01A2.

SU-E-T-226: Clinical Implementation of a Gravity-Oriented Wedge for Total Body Irradiation

PURPOSE

To describe a TBI technique designed within the limits of a small-room geometry and its clinical implementation.

METHODS

Following construction of the universal treatment devices, including the double-wedge, beam spoiler table, and patient support table, commissioning consists of measurements to determine the output, tissue-phantom ratio, effective source distance, and off-axis factor. Dose is calculated by applying these factors per patient-specific measurements to arbitrary point in the patient. Typically, ten calculation points are located at mid-separation along the mid-sagittal plane from the head to the ankles. When areas of unacceptably high dose are calculated, custom compensators are constructed from 5-mm sheets of PMMA and placed over the patient on top of the beam spoiler table. The typical dose homogeneity of the planning calculations is within 2% of the prescribed dose.

RESULTS

To verify the accuracy of the technique, an anthropomorphic phantom was simulated and treated. In total, 128 thermoluminescent dosimeters (TLDs) were irradiated within the phantom. Concentrations of TLDs were located in the planes of selected calculation points, i.e. the head, neck, sternum, lung, umbilicus, and pelvis. Results showed the average dose to these locations differed from the intended dose by -3.5%, 3.4%, 2.6%, 9.5%, 2.8%, and 0.5%, respectively. Due to its heterogeneous material, a higher discrepancy in the lung dose was anticipated. To demonstrate the dosimetric size of the radiation field, ionization chamber measurements were taken on one lateral side of the treatment area at a constant depth of 5 cm. A few measurements on the contralateral side were within 1 %, verifying the field's lateral symmetry. The approximate treatment area for the current technique is approximately 180×50 cm.

CONCLUSIONS

We have demonstrated a small-room technique capable of meeting the dosimetric goal of TBI. To improve the dosimetric characteristics, new universal treatment devices are currently being designed and constructed.

Risk of breast fibrosis following irradiation using a breast-specific SBRT system compared with conventional APBI

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Background: To determine the dosimetric characteristics and risk of breast fibrosis using a normal tissue complication probability (NTCP) model in conjunction with a novel preoperative stereotactic radiotherapy system called the GammaPod. Results are compared with linac based post-lumpectomy APBI plans for the same cohort.

Methods: The GammaPod breast SBRT system consists of a Co-60 irradiation unit in combination with an immobilization device with embedded fiducials. Eight patients were enrolled in an IRB-approved protocol and underwent CT scans in the prone position with breast immobilization. A preoperative target (GTV) was synthesized to match the tumor location and volume reported in imaging studies obtained prior to surgery (0.3-2.4 cc). The GTV was expanded by 1.5 cm to create a CTV, and a PTV was created using an additional 0.3 cm margin. The PTV was prescribed 25.5 Gy in 3 fx, which is radiobiologically equivalent to conventional APBI doses of 38.5 Gy in 10 fx. Following the radioablative experience in NSCLC, we also planned to deliver 60.0 Gy to the GTV+0.3 cm as a simultaneous boost in conjunction with the 25.5 Gy PTV prescription dose. For comparison, linac-based treatment plans were created for the same cohort following NSABP B-39 guidelines. Whole breast dosimetry was analyzed in terms of biologically equivalent dose (BED) and Lyman NTCP analysis was performed.

Results: The volume of ipsilateral breast receiving 10, 20, 50, and 100% of the prescribed dose was substantially smaller in GammaPod vs. APBI plans, with cohort averages of 19.3, 13.0, 7.1 and 4.0% vs. 75.8, 67.3, 48.1 and 27.6% respectively (p<0.001). Even though the PTV equivalent uniform BED (EUD) was substantially higher in GammaPod plans (87.9 Gy vs. 57.3 Gy), the ipsilateral breast EUD was still smaller in these plans, 18.9 ± 5.0 Gy vs. 47.2 ± 3.2 Gy (p<0.001). Corresponding NTCP predictions for breast fibrosis rates following GammaPod and APBI treatments were 0.2 ± 0.1% vs. 2.8 ± 0.8% (p<0.001), respectively.

Conclusions: The GammaPod system improves upon traditional post-lumpectomy linac-based APBI by decreasing dose to the ipsilateral breast as well as the predicted rates of breast fibrosis.