ImportanceCompared with 3-dimensional conformal radiotherapy (3DCRT), intensity-modulated radiotherapy (IMRT) can spare nearby tissue but may result in increased scatter radiation to distant normal tissue, including red bone marrow. It is unclear whether second primary cancer risk varies by radiotherapy type.ObjectiveTo evaluate whether radiotherapy type (IMRT vs 3DCRT) is associated with second primary cancer risk among older men treated for prostate cancer.Design, Setting, and ParticipantsIn this retrospective cohort study of a linked database of Medicare claims and Surveillance, Epidemiology, and End Results (SEER) Program population-based cancer registries (2002-2015), male patients aged 66 to 84 diagnosed with a first primary nonmetastatic prostate cancer from 2002 to 2013, as reported to SEER, and who received radiotherapy (IMRT and/or 3DCRT without proton therapy) within the first year following prostate cancer were identified. The data were analyzed from January 2022 through June 2022.ExposureReceipt of IMRT and 3DCRT, based on Medicare claims.Main Outcomes and MeasuresThe association between radiotherapy type and development of a subsequent hematologic cancer at least 2 years after prostate cancer diagnosis or a subsequent solid cancer at least 5 years after prostate cancer diagnosis. Hazard ratios (HRs) and 95% CIs were estimated using multivariable Cox proportional regression.ResultsThe study included 65 235 2-year first primary prostate cancer survivors (median [range] age, 72 [66-82] years; 82.2% White patients) and 45 811 5-year survivors with similar demographic characteristics (median [range] age, 72 [66-79] years; 82.4% White patients). Among 2-year prostate cancer survivors (median [range] follow-up, 4.6 [0.003-12.0] years), 1107 second hematologic cancers were diagnosed (IMRT, 603; 3DCRT, 504). Radiotherapy type was not associated with second hematologic cancers overall or any specific types evaluated. Among 5-year survivors (median [range] follow-up, 3.1 [0.003-9.0] years), 2688 men were diagnosed with a second primary solid cancer (IMRT, 1306; 3DCRT, 1382). The overall HR for IMRT vs 3DCRT was 0.91 (95% CI, 0.83-0.99). This inverse association was restricted to the earlier calendar year period of prostate cancer diagnosis (HR2002-2005 = 0.85; 95% CI, 0.76-0.94; HR2006-2010 = 1.14; 95% CI, 0.96-1.36), with a similar pattern observed for colon cancer (HR2002-2005 = 0.66; 95% CI, 0.46-0.94; HR2006-2010 = 1.06; 95% CI, 0.59-1.88).Conclusions and RelevanceThe results of this large, population-based cohort study suggest that IMRT for prostate cancer is not associated with an increased risk of second primary cancers, either solid or hematologic, and any inverse associations may be associated with calendar year of treatment.
Additive manufacturing, or 3D printing, of the bioresorbable polymer e-polycaprolactone (PCL) is an emerging tissue engineering solution addressing patient specific anatomies. Predictively modeling the mechanical behavior of 3D printed parts comprised of PCL improves the ability to develop patient specific devices that meet design requirements while reducing the testing of extraneous design variants and development time for emergency devices. Predicting mechanical behavior of 3D-printed devices is limited by the variability of effective material moduli that are determined in part by the 3D printing manufacturing process. Powder fusion methods, specifically laser sintering, are known to produce parts with internal porosity ultimately impacting the mechanical performance of printed devices. This study investigates the role of print direction and part size on the material and structural properties of laser sintered PCL parts. Solid PCL cylinders were printed in the XY (perpendicular to laser) and Z direction (parallel to laser), scanned using microcomputed tomography, and mechanically tested under compression. Compositional, structural, and functional properties of the printed parts were evaluated with differential scanning calorimetry, gel permeation chromatography, microcomputed tomography, and mechanical
12005 Background: Radiotherapy-related adverse effects such as the development of subsequent neoplasms cause significant morbidity among prostate cancer survivors. Advances in radiotherapy techniques, including intensity-modulated radiation therapy (IMRT) and proton beam radiotherapy (PBRT), have aimed to reduce exposure to adjacent healthy tissues to reduce adverse effects. Initial reports based on small sample sizes and limited follow up (through 2011) have suggested reduced risks for subsequent colon and rectal cancers following IMRT compared to 3D conformal radiotherapy (CRT) for prostate cancer patients, but not for subsequent bladder cancer. We sought to extend previous reports with larger sample size and longer follow up. Methods: We conducted a retrospective cohort study within the linked database of Surveillance, Epidemiology and End Results (SEER) cancer registries and Medicare claims. The cohort included men diagnosed with first primary non-metastatic prostate cancer at ages 66-84 during 2002-2011; received initial IMRT, PBRT, or CRT; and survived without developing a second primary cancer ≥5 years after diagnosis (follow up through 2016). Cox regression models estimated risks of second primary solid tumors after IMRT and PBRT vs CRT, adjusting for age at prostate cancer diagnosis, tumor grade, race, Charlson comorbidity score, and receipt of initial prostate cancer therapy. Results: The cohort (median follow-up = 8.4 years) included 51,020 patients, of whom 19,536 received CRT alone, 29,868 received IMRT without PBRT, and 1,616 received PBRT. Compared to patients who received CRT (n = 1,348, 7.0%), both IMRT (n = 1,289, 4.3%; hazard ratio [HR] = 0.87; 95% confidence interval [CI], 0.80-0.95) and PBRT (n = 83, 5.1%; HR = 0.77; 95% CI 0.62-0.97) showed a decrease in risk of developing any second solid malignancy. In analyses by second cancer type, risks of colon cancer (HR = 0.70; 95%CI, 0.52-0.94) and bladder cancer (HR = 0.79; 95%CI, 0.65-0.97) were significantly lower after IMRT than CRT, whereas no association was observed for anorectal cancers (HR = 1.00; 95%CI, 0.65-1.53). Further investigation by time since prostate cancer diagnosis revealed a time-dependent decrease after IMRT compared to CRT in risk for bladder cancer (HRs = 0.94, 0.87, 0.61 for 5-7.4, 7.5-9.9, and 10+ years respectively) and anorectal cancer (HRs = 1.22, 0.97, 0.78), whereas the opposite trend was observed for colon cancer (HRs = 0.70, 0.68, 1.05). Conclusions: In this large cohort with increased follow-up time compared with previous reports, we observed reduced risk of colon and bladder cancer with IMRT overall, as well as time-dependent patterns for bladder and anorectal cancer that were consistent with improved tumor targeting. Further research is needed with larger sample sizes to evaluate long-term effects after PBRT. Our study supports the value of quantifying adverse effects as radiotherapy techniques evolve.
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