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Session Item

Physics track: Implementation of new technology, techniques, clinical protocols or trials (including QA & audit)
Poster
Physics
00:00 - 00:00
Dosimetric analysis of simultaneous integrated boost in the HYPORT Adjuvant Trial (NCT03788213)
PO-1797

Abstract

Dosimetric analysis of simultaneous integrated boost in the HYPORT Adjuvant Trial (NCT03788213)
Authors: BHUSAL|, Subecha(1)*[BHSUBECHA@GMAIL.COM];Chatterjee|, Sanjoy(1);Chakraborty|, Santam(1);Kumari|, Abha(1);Bachianathan|, Silvamani (2);Mahato|, Anurupa(1);Lal|, Punita(3);Gupta |, Subhash (4);Solomon |, Patricia (2);Das|, KJ Maria(3);Mandal|, Samar(1);
(1)Tata Medical Center, Radiation Oncology, Kolkata, India;(2)Christian Medical College, Radiation Oncology, Vellore, India;(3)Sanjay Gandhi Post Graduate Institute of Medical Sciences, Radiation Oncology, Lucknow, India;(4)All India Institute of Medical Sciences, Radiation Oncology, Delhi, India;
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Purpose or Objective

The HYPORT adjuvant trial is a randomized trial comparing a one week (5 fractions) schedule of hypofractionated breast radiotherapy against a three week (15 fractions) schedule. As a part of this study, patients who have undergone breast conservation can undergo a Simultaneous Integrated Boost (SIB) to the boost cavity.

Material and Methods

The HYPORT Adjuvant is a multi-centric, open-label, phase III, parallel-group, two-arm randomized controlled trial. Patients requiring adjuvant radiotherapy after curative intent, margin negative,  surgery are eligible. Patients were randomized to 

  • Standard arm: 40 Gy in 15 fractions over 3 weeks to the whole breast +/- regional nodal RT 

  • Experimental arm: 26 Gy in 5 fractions over 1 week to the same volumes. 

Patients undergoing BCS were eligible for SIB. A boost target volume (BTV) was generated around the tumor bed (marked with clips) by an isotropic expansion of 5 mm. A hybrid tangent beam whole breast radiation plan with a Volumetric Modulated Arc SIB (VMAT SIB) was used for SIB. The VMAT plan comprised of two coplanar  30-40 degree complementary arcs offset at an angle of 5 - 10 degree from the tangent. Doses of 8 Gy in 15 fractions and 6 Gy in 5 fractions is used for tumor bed boost in the standard and experimental arms, respectively. 

In the current study, we report adherence to the protocol and compare the dosimetry data between two arms. 

Results

The trial opened for accrual on 28th March 2019 and 185 patients were enrolled in the study till September 2019. Sixty-four (34.6%) patients underwent BCS and of them,  58 (90%) patients received SIB.

Conclusion

SIB plans in the standard and experimental arms of the HYPORT Adjuvant trial met the protocol defined constraints in all patients. The SIB strategy enabled the dosimetric sparing of the normal organs (especially contralateral lung, breast and heart) while ensuring conformity and homogeneity.