From this perspective, we wonder about the clinical implications of oncology recapturing ontogeny in the contexts of neoantigens, tumor biomarkers, and cancer targets. We ponder about the biological ramifications of finding remnants of mini-organs and residuals of tiny embryos in some tumors. We reminisce about classical experiments showing that the embryonic microenvironment possesses antitumorigenic properties. Ironically, a stem-ness niche—in the wrong place at the wrong time—is also an onco-niche. We marvel at the paradox of TGF-beta both as a tumor suppressor and a tumor promoter. We query about the dualism of EMT as a stem-ness trait engaged in both normal development and abnormal disease states, including various cancers. It is uncanny that during fetal development, proto-oncogenes wax, while tumor-suppressor genes wane. Similarly, during cancer development, proto-oncogenes awaken, while tumor-suppressor genes slumber. Importantly, targeting stem-like pathways has therapeutic implications because stem-ness may be the true driver, if not engine, of the malignant process. Furthermore, anti-stem-like activity elicits anti-cancer effects for a variety of cancers because stem-ness features may be a universal property of cancer. When a fetus survives and thrives despite immune surveillance and all the restraints of nature and the constraints of its niche, it is a perfect baby. Similarly, when a neoplasm survives and thrives in an otherwise healthy and immune-competent host, is it a perfect tumor? Therefore, a pertinent narrative of cancer depends on a proper perspective of cancer. If malignant cells are derived from stem cells, and both cells are intrinsically RB1 negative and TP53 null, do the absence of RB1 and loss of TP53 really matter in this whole narrative and an entirely different perspective of cancer?
Purpose/Objective(s)Accurate target delineation/contouring is essential for radiation treatment planning and radiotherapy efficacy. As a result, improving the quality of target delineation is an important goal in the education of radiation oncology residents. The purpose of this study was to track the concordance of radiation oncology residents’ contours with faculty physicians’ contours over the course of one year to assess for patterns.Materials/MethodsResidents in PGY levels of 2-4 were asked to contour target volumes which were compared to the finalized, faculty physician-approved contours. Concordance between resident and faculty physician contours was determined by calculating the Jaccard Concordance Index (JCI), ranging from 0 or no agreement to 1 or complete agreement. Mutivariate mixed effect models were used to assess the association of JCI to the fixed effect of PGY level and its interactions with cancer type and other baseline characteristics. Post hoc means of JCI were compared between PGY levels after accounting for multiple comparisons using a Tukey’s method.ResultsIn total, 958 structures from 314 patients collected during the 2020-2021 academic year were studied. The mean JCI was 0.77, 0.75, and 0.61 for the levels of PGY-4, PGY-3, and PGY-2, respectively. JCI score in PGY-2 was found lower than those of PGY-3 and PGY-4 respectively (P’s<0.001). No statistically significant difference of JCI score was found when comparing between PGY-3 and PGY-4 levels. The average JCI score was lowest (0.51) for primary head/neck cancers and highest (0.80) for gynecologic cancers.ConclusionTracking and comparing the concordance of resident contours and faculty physician contours is an intriguing method of assessing resident performance in contouring and target delineation and could potentially serve as a quantitative metric in radiation oncology resident evaluation, which is lacking currently. However, additional study is necessary before this technique can be incorporated into residency assessments.
Purpose:
This dosimetric study is intended to lower the modulation factor in lung SBRT plans generated in the Eclipse TPS that could replace highly modulated plans that are prone to the interplay effect.
Materials and Methods
Twenty clinical lung SBRT plans with high modulation factors (≥4) were replanned in Varian Eclipse TPS version 15.5 utilizing 2 mm craniocaudal and 1 mm axial block margins followed by light optimization in order to reduce modulation. A Desai et al.1 style optimization, which utilizes a novel shell structure (OptiForR50) for R50% optimization in addition to five consecutive concentric 5 mm shells, was utilized to control dose falloff according to RTOG 0813 & 0915 recommendations. The prescription varied from 34-54 Gy in 1-4 fractions, and the dose objectives were PTV D95% = Rx, PTV Dmax < 140% of Rx, and minimizing the modulation factor. Plan evaluation metrics included modulation factor, CIRTOG, homogeneity index (HI), R50%, D2cm, V105%, and lung V8-12.8Gy (Timmerman Constraint). A random-intercept linear mixed effects model was used with a p≤0.05 threshold to test for statistical significance.
Results
The retrospectively generated plans had significantly lower modulation factors (3.65±0.35 vs 4.59±0.54; p<0.001), lower CIRTOG (0.97±0.02 vs 1.02±0.06; p=0.001), higher HI (1.35±0.06 vs 1.14±0.04; p<0.001), lower R50% (4.09±0.45 vs 4.56±0.56; p<0.001), and lower lungs V8-12.8Gy (Timmerman) (4.61%±3.18% vs 4.92%±3.37%; p<0.001). The high dose spillage V105% was borderline significantly lower (0.44%±0.49% vs 1.10%±1.64%; p=0.051). The D2cm was not statistically different (46.06%±4.01% vs 46.19%±2.80%; p=0.835).
Conclusion
Lung SBRT plans with significantly lower modulation factors can be generated that meet the RTOG constraints, using our planning strategy.
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