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Vienna, Austria

ESTRO 2023

Session Item

Dose calculation
7000
Poster (Digital)
Physics
Heterogeneously Hypo-fractionated RT for LA-NSCLC (the HERAN trial): Clinical treatment plan results
Lone Hoffmann, Denmark
PO-1831

Abstract

Heterogeneously Hypo-fractionated RT for LA-NSCLC (the HERAN trial): Clinical treatment plan results
Authors:

Lone Hoffmann1,4, Ane Appelt2,3, Marianne M Knap1, Ditte S Møller1,4, Torben S Hansen5, Charlotte Christiansen5, Mikkel D Lund6, Morten Nielsen7, Tine B Nielsen7, Tine Schytte8,9, Rune Thing10, Azza A Khalil1,11

1Aarhus University Hospital, Department of Oncology, Aarhus, Denmark; 2University of Leeds , Leeds Institute of Medical Research at St James's, Leeds, United Kingdom; 3 St James's University Hospital, Leeds Cancer Centre, Leeds, United Kingdom; 4Aarhus University, Department of Clinical Medicine, Faculty of Health Sciences, Aarhus, Denmark; 5Vejle Hospital, University Hospital of Southern Denmark, Department of Oncology, , Vejle, Denmark; 6Vejle Hospital, University Hospital of Southern Denmark, , Department of Oncology, Vejle, Denmark; 7Odense University Hospital, Laboratory of Radiation Physics, Odense, Denmark; 8Odense University hospital, Department of Oncology, Odense, Denmark; 9University of Southern Denmark, Department of Clinical Research, Odense, Denmark; 10Vejle Hospital, University Hospital of Southern Denmark, Department of Oncology, Vejle, Denmark; 11Faculty of Health Sciences, Department of Clinical Medicine, Aarhus, Denmark

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Purpose or Objective

Treatment options for frail patients with locally-advanced non-small cell lung cancer (LA-NSCLC) unfit for standard chemoradiotherapy regimes (60-66Gy in 30-33 fractions) are meagre. A shorter radical radiotherapy schedule with heterogeneous dose escalation to the gross tumour, keeping normal tissue toxicity low, can be a favourable option. The national Danish HERAN trial (NCT03742687) aims to test this approach. We report on clinical dose planning results for the first 104 patients treated on the trial.

Material and Methods

HERAN is a non-randomised multicentre phase II feasibility study, enrolling patients with inoperable NSCLC stage IIA-IV disease not candidates for standard chemoradiotherapy. Gross tumour volumes of primary tumours (GTV-T) and lymph nodes with a diameter >3cm (GTV-Nlarge) are treated with mean doses of up to 66Gy in 24 fractions, with overall Dmax≤74Gy.
Dose to the remaining targets (GTV-N, CTV and PTV) must be covered by 95% of 50Gy, but is not intentionally increased above 50Gy. Dose escalation is limited by constraints to PTV-CTV (volume of PTV subtracted CTV) and organs at risk (OAR). The dose to the 1cm3 receiving the highest dose (D1cc) of PTV-CTV  and 1cm3 of tissue outside PTV may increase to 65Gy. OAR constraints are Spinal Cord D0.05cc<45Gy; Lungs Dmean<20Gy, V20Gy<35%; Heart V30Gy<40%; and Esophagus D1cc<58Gy.

Results

The study started enrolment in 2017. Currently, 104 patients from three Danish centres have been treated on trial, of which the majority had performance status 2 and stage IIIA-IV disease. Clinical and dosimetric data are summarised in Table 1. Mean doses to GTV-T and GTV-Nlarge were escalated to median 65.6Gy, i.e. close to the aim of 66Gy, despite GTV-T volumes up to 529.2cm3. Plans all complied with OAR constraints. In Figure 1, a comparison between a normo-fractionated 66Gy/33fraction plan and an experimental HERAN plan is shown for one patient. It illustrates that the GTV-T receives the same dose (mean dose: 66Gy) for the normo-fractionated plan and the HERAN plan, while the dose to CTV and PTV volumes is reduced for the HERAN plan (1.A and 1.B). The minimum acceptable dose at the PTV border is 47.5Gy. The de-escalation of the dose peripherally in the target leads to decreased dose to the OAR (1.C). In all patients, a high degree of dose escalation was achieved. Figure 1.D shows the dose volume histogram (DVH) distribution for GTV-T for all 104 treatment plans. The HERAN plans were delivered in 24 fractions. Thus, the mean GTV-T dose was approximately 2.75 Gy/fraction.

Conclusion

Heterogeneous, hypo-fractionated treatment planning is feasible for LA-NSCLC patients not candidates for standard chemoradiotherapy. Tumour dose escalation (66Gy in 24 fractions) is possible while keeping the dose to OAR low in a multicentre setting. Clinical outcomes are expected in 2023.