onc brain

About · curated by Nick Boehling, MD · @nb2276

    Cross-cutting

    3 studies across 1 date

    2026-11-10

    NTCP, TCP and the TECs (QUANTEC, HyTEC, PENTEC)

    TL;DRNarrative review of TCP/NTCP outcome modeling through the QUANTEC, HyTEC and PENTEC normal-tissue projects; no effect sizes reported in source.

    Trials discussed

    QUANTECHyTECPENTEC

    vs leading data
    • AAPM/ASTRO TEC projects covered
    6 details
    Methods
    • 🔍 Single-author first-person review in Medical Physics, not a systematic review or new dataset
    • 🔍 Frames RT as a tradeoff: high TCP vs low NTCP
    • 🔍 Draws on in-house institutional outcome data alongside the TEC work
    Results
    • 📊 No effect size, dose-volume constraint or model parameter reported in source abstract
    Critique
    • ⚠️ Author's premise: dosimetric and clinical correlates of outcome rarely form a unified picture
    • ⚠️ Written by a TEC participant; not an independent appraisal of those constraints
    Open questions
    • Unified dosimetric and clinical correlates of TCP and NTCP
    📚 Sources · 📄 1 paper
    📄 PAPER Yorke, Ellen · Medical Physics (2023-02)
    Modeling clinical outcomes in radiotherapy: NTCP, TCP and the “TECs”
    doi
    Abstract
    Abstract Radiation therapy is a double‐edged sword which damages both tumor and normal cells. Achieving treatments with high tumor control probability (TCP) yet low normal tissue complication probability (NTCP) is often a struggle because we rarely have a unified understanding of the dosimetric and clinical correlates of the desired outcomes. I am fortunate to have participated in some of these struggles, including analyzing and using in‐house data and being involved in the AAPM and ASTRO “TEC” projects—QUANTEC (Quantitatie Analysis of Normal Tissue Effects in the Clinic), HyTEC (Hypofractionated Treatment Effects in the Clinic) and PENTEC (Pediatric Normal Tissue Effects in the Clinic).

    Radiation

    Biological principles of SBRT/SRS: indirect cell death

    TL;DRAbove ~10 Gy/fraction, SBRT/SRS adds indirect tumor cell death via vascular injury and antitumor immunity on top of direct cell kill.

    Why it mattersRadiation oncology

    The parameter the review keys on is dose per fraction: above ~10 Gy/fraction, vascular injury and immune effects add tumor kill beyond direct cytotoxicity. That frames ablative few-fraction schedules as biologically distinct from moderate hypofractionation, though the authors flag the normal tissue mechanism at these doses as unresolved.

    6 details
    Design

    Narrative review of prior reports and recent observations on high-dose effects on tumor cell survival, tumor vasculature and antitumor immunity. No search strategy or inclusion criteria stated in the abstract.

    Discussion

    Proposes that SBRT/SRS efficacy reflects indirect cell death (vascular damage above ~10 Gy/fraction, plus antitumor immunity) in addition to direct kill. Does not settle the normal tissue mechanism at these doses.

    Open questions
    • Mechanism of normal tissue damage after high-dose irradiation
    • Which approaches best augment SBRT-induced antitumor immunity
    📚 Sources · 📄 1 paper
    📄 PAPER Song, Chang W.; Glatstein, Eli; Marks, Lawrence B. et al. · International Journal of Radiation Oncology*Biology*Physics (2021-05)
    Biological Principles of Stereotactic Body Radiation Therapy (SBRT) and Stereotactic Radiation Surgery (SRS): Indirect Cell Death
    doi
    Abstract
    Purpose To review the radiobiological mechanisms of stereotactic body radiation therapy stereotactic body radiation therapy (SBRT) and stereotactic radiation surgery (SRS). Methods and materials We reviewed previous reports and recent observations on the effects of high-dose irradiation on tumor cell survival, tumor vasculature, and antitumor immunity. We then assessed the potential implications of these biological changes associated with SBRT and SRS. Results Irradiation with doses higher than approximately 10 Gy/fraction causes significant vascular injury in tumors, leading to secondary tumor cell death. Irradiation of tumors with high doses has also been reported to increase the antitumor immunity, and various approaches are being investigated to further elevate antitumor immunity. The mechanism of normal tissue damage by high-dose irradiation needs to be further investigated. Conclusions In addition to directly killing tumor cells, high-dose irradiation used in SBRT and SRS induces indirect tumor cell death via vascular damage and antitumor immunity. Further studies are warranted to better understand the biological mechanisms underlying the high efficacy of clinical SBRT and SRS and to further improve the efficacy of SBRT and SRS.

    Radiation

    PENTEC vs QUANTEC/HyTEC: late effects in children vs adults

    TL;DRNo effect size reported in source; organ-by-organ synthesis finds pediatric late-effect risk similar, greater, or less than adult, depending on tissue and age.

    Trials discussed

    QUANTECHyTECPENTEC

    Why it mattersRadiation oncology

    Adult QUANTEC/HyTEC constraints do not transfer uniformly to children: neurocognition, cerebrovascular and breast-lactation risks run greater in children, ovary less, lung perhaps slightly less. Within the pediatric range, younger children carry greater hearing and neurocognitive risk, so age at RT should modify how a constraint is read when planning brain or posterior fossa fields. The longer read

    6 details
    Design

    Narrative comparison of PENTEC with the adult QUANTEC and HyTEC efforts across content, oversight, support, scope and literature-review method, followed by organ-specific pediatric findings.

    Results

    Child vs adult risk is similar for brain necrosis, optic apparatus, parotid and liver; greater for neurocognition, cerebrovascular and breast lactation; less for ovary; perhaps slightly less for lung. Maldevelopment of musculoskeletal tissue, teeth, breast and reproductive organs is relevant primarily only in children.

    Organ / endpointChildren vs adultsYounger vs older children
    Brain, necrosisSimilarNot stated
    Optic apparatusSimilarNot stated
    ParotidSimilarNot stated
    LiverSimilarNot stated
    Brain, neurocognitionGreaterGreater in younger
    CerebrovascularGreaterNot stated
    Breast, lactationGreaterNot stated
    LungPerhaps slightly lessNot stated
    OvaryLessLesser in younger
    HearingNot statedGreater in younger
    ThyroidNot statedLesser in younger
    Musculoskeletal, teeth, breast, reproductive maldevelopmentRelevant primarily only in childrenNot stated
    vs leading data

    QUANTEC and HyTEC remain the adult reference for conventional and hypofractionated constraints; PENTEC is the pediatric counterpart, and this paper is the first framing of where the two sets diverge by organ.

    Applies to
    pediatric and adolescent cancer survivors whose normal tissues received RT
    Does not represent a validated age-adjusted constraint set for direct substitution into adult or pediatric planning.
    Limitations

    Comparisons are confounded by treatment paradigm (cancer type, dose, fields, chemo), and the optimal age model (continuous vs groupings) is unresolved.

    Discussion

    Age and developmental status modify risk in organ-specific directions, so a single age cutoff for applying adult or pediatric constraints is not supported. The authors state further work is needed to define how age shapes risk.

    Open questions
    • Should age enter NTCP models as continuous or developmental groupings?
    • Do child vs adult differences persist after adjusting for fields and chemo?
    📚 Sources · 📄 1 paper
    📄 PAPER Milano, Michael T.; Marks, Lawrence B.; Olch, Arthur J. et al. · International Journal of Radiation Oncology*Biology*Physics (2024-06)
    Comparison of Risks of Late Effects From Radiation Therapy in Children Versus Adults: Insights From the QUANTEC, HyTEC, and PENTEC Efforts
    doi
    Abstract
    Pediatric Normal Tissue Effects in the Clinic (PENTEC) seeks to refine quantitative radiation dose-volume relationships for normal-tissue complication probabilities (NTCPs) in survivors of pediatric cancer. This article summarizes the evolution of PENTEC and compares it with similar adult-focused efforts (eg, Quantitative Analysis of Normal Tissue Effects in the Clinic [QUANTEC] and Hypofractionated Treatment Effects in the Clinic [HyTEC]) with respect to content, oversight, support, scope, and methodology of literature review. It then summarizes key organ-specific findings from PENTEC in an attempt to compare NTCP estimates in children versus adults. In brief, select normal-tissue risks within developing organs and tissues (eg, maldevelopment of musculoskeletal tissue, teeth, breasts, and reproductive organs) are primarily relevant only in children. For some organs and tissues, children appear to have similar (eg, brain for necrosis, optic apparatus, parotid gland, liver), greater (eg, brain for neurocognition, cerebrovascular, breast for lactation), less (ovary), or perhaps slightly less (eg, lung) risks of toxicity versus adults. Similarly, even within the broad pediatric age range (including adolescence), for some endpoints, younger children have greater (eg, hearing and brain for neurocognition) or lesser (eg, ovary, thyroid) risks of radiation-associated toxicities. NTCP comparisons in adults versus children are often confounded by marked differences in treatment paradigms that expose normal tissues to radiation (ie, cancer types, prescribed radiation therapy dose and fields, and chemotherapy agents used). To add to the complexity, it is unclear if age is best analyzed as a continuous variable versus with age groupings (eg, infants, young children, adolescents, young adults, middle-aged adults, older adults). Further work is needed to better understand the complex manner in which age and developmental status affect risk.

    Radiation