Recurrent early stage endometrial cancer: Patterns of recurrence and results of salvage therapy.

OBJECTIVE: To analyze our institutional experience and oncologic outcomes for salvage treatment for the recurrence of early-stage endometrial cancer patients. METHODS: We included women of all ages diagnosed with FIGO stage I-II, any grade endometrial cancer from 2000 to 2016 at our institutions who were treated with at least a hysterectomy. Recurrences in the pelvis and/or vagina were considered locoregional recurrences (LRR). Overall survival (OS) was assessed using Kaplan-Meier survival analysis. Univariate (UV) and multivariate (MV) Cox proportional hazards modeling was also used. RESULTS: A total of 2691 women were analyzed. The majority had endometrioid histology (91%), stage IA disease (61%), and were grade 1 (57%). With a median follow-up of 6.1 years, the overall rate of recurrence was 7.2%, and the rate of LRR was 3.7%. Women with vaginal-only recurrences had a longer median OS after recurrence (14.0 years) compared to both pelvic (1.2 years) and distant (1.0 year) failures. For women with vaginal-only recurrences, salvage radiotherapy (RT) was the only factor associated with improved OS on MVA (HR 0.1, p = .04). For women with pelvic recurrences, salvage surgery (HR 0.3, p = .01), salvage RT (HR 0.3, p < .01), and salvage chemotherapy (HR 0.4, p = .03) were associated with improved OS. CONCLUSIONS: Failure rates for women with early-stage endometrial cancer are low. Women with vaginal-only recurrences have improved OS compared to pelvic or distant recurrences. Salvage RT appears to be an important factor for treatment of women with vaginal-only recurrences. Aggressive multimodality treatment may be beneficial for women with pelvic recurrences.

An evaluation of the consistency of shifts reported by three different systems for non-coplanar treatments.

Treatment of intra-cranial lesions sometimes requires a non-coplanar beam configuration. One of the most commonly used IGRT modalities, kV conebeam CT, cannot typically be used when large couch rotations are introduced. However, multiple other systems allow for imaging/tracking the patient for such situations. This work compares shift consistency from three independent systems, namely Varian's Advanced Imaging, Brainlab's Exactrac and Varian's OSMS, all installed on the same linear accelerator. After a phantom was first positioned using conebeam CT, the three systems were used to determine shifts at different couch positions. This was done with and without intentional shifts inserted in the original phantom position. Results show that the difference in shifts between the three systems was never more than 0.7 mm (average of 0.2 mm, standard deviation of 0.2 mm). These results confirm that all three systems are equivalent to within 1 mm and may potentially be uses interchangeably, especially in cases where the PTV margin is on the order of 1 mm.

Dosimetric evaluation of abdominal compression as a method to reduce the incidence of radiation-induced pneumonitis in lung SBRT treatment.

Abdominal compression has been shown to reduce the extent of lung tumor motion but the dosimetric impact of the approach is still in need of investigation. The current work analyzes the impact of various changes in PTV volume on key metrics of the final dose distribution to normal lung. To add clinical perspective, we also provide NTCP calculations for grade 2+ pneumonitis for each case. For a total of seventeen cases, the original ITV/PTV was reduced by systematically varied amounts and SBRT plans using dynamic conformal arc and VMAT techniques were created. DVH analysis for the normal lung comparing the original plan to the one with the ITV reduced by up to 10 mm shows that the average reduction of V5, V20 and mean lung dose is 3.8%, 2.0% and 1.1 Gy, respectively, for the conformal arc plans. Corresponding values for the VMAT plans were 3.9%, 1.9% and 1.2 Gy respectively. The mean NTCP drop for the conformal arc plans was 2.0% while it was 1.9% for the VMAT plans. These results suggest that abdominal compression has a modest impact on NTCP and on dosimetric parameters typically used to predict the risk of radiation pneumonitis in patients undergoing lung SBRT.

Head to head comparison of two commercial phantoms used for SRS QA.

Multiple commercial phantoms are now available for performing end-to-end QA testing for stereotactic procedures. This project aims at directly comparing one of the newest phantoms on the market against a more established one by performing similar tests to determine whether results are similar and they can be used interchangeably. Both phantoms were used to evaluate the coincidence of radiation and laser isocenters of a linear accelerator. End-to-end dosimetric tests were also performed using both an ion chamber and film. As part of the testing, both phantoms were also evaluated in terms of their efficiency of setup as well as the time required to switch inserts for different tests. Results showed that the laser/radiation isocenter coincidence as determined from each phantom was highly correlated. Ion chamber results were within 0.5% of the expected values. Gamma (2%, 2mm) pass rates of corresponding films were within 2% between phantoms. These results show that both phantoms are capable of producing equivalent results for the QA tests evaluated here.