ESTRO 2022 - Abstract Book

S301

Abstract book

ESTRO 2022

Sunday 8 May 2022

Teaching lecture: MR-guided radiotherapy: How to acquire and interpret imaging data for online adaption

SP-0337 MR-guided radiotherapy: How to acquire and interpret imaging data for online adaption

L. Boldrini

1 Italy Abstract not available

Teaching lecture: Mitochondria in tumour and normal tissue radiobiology

SP-0338 Mitochondria in tumour and normal tissue radiobiology

F. Paris 1

1 France Abstract not available

Teaching lecture: Breast cancer-related lymphoedema

SP-0339 Breast cancer-related lymphoedema

L. Boersma 1

1 Maastricht University Medical Centre+, Maastricht, The Netherlands , Dept Radiation Oncology ( Maastro), GROW School for Oncology and Developmental Biology,, Maastricht, The Netherlands

Abstract Text Introduction

The incidence of lymph-edema in breast cancer patients can rise to 40% [1, 4]. The symptoms consist of a tired or heavy feeling, pain, tingling, limitations in movement, limitations in daily functioning, skin abnormalities and increased risk of infections. Lymph-edema arises when balance between supply and drainage of lymphatic fluid is disturbed [6]. It has a major impact on people's daily lives, having both physical and psychological consequences. A commonly and widely used staging system of the International Society of Lymphology (ISL) distinguishes in the development of lymph-edema three stages (stages 1-3) [2]: Stage 1: Presence of edema reduced by treatment or arm elevation (pitting edema); Stage 2: Edema partially reduced by treatment (pitting and non-pitting edema), intractable and progressive; Stage 3: Elephantiasis with skin lesions and relapsing infections. Diagnosis The complaints and physical examination together with measuring the swelling are the most important starting point for diagnosis. Different methods have been described on how to measure swelling, all with their pros and cons [4]. A 2 cm increase in circumference, measured at 10 cm from the olecranon, is commonly used to define lymph-edema, but there is no international consensus on the exact point from when one speaks of 'clinically relevant' lymph-edema and on the point from when one should start treatment, since it also depends on the possible presence of other signs of lymph-edema. The Dutch guideline proposes to define lymph-0edema when the volume is increased with 5-10%, corresponding to grade 1 toxicity on the CTC-AE 5.0 scale. Preventing lymph-edema Risk factors for developing lymph-edema, consist of patient-related and treatment-related risk factors. The most important factors that can be influenced by the patient herself consist of obtaining a healthy BMI (< 25 kg/ m2), adequate skin care and sufficient physical exercise, since this is important to stimulate the pump function of the muscles. Other non-modifiable patient-related factors are genetic factors: recent and ongoing studies in treatment- induced lymph-edema have suggested (epi) genetic predispositions yielding an increased risk of developing lymph-edema [4]. Treatment-related risk factors are the extent of axillary surgery, radiotherapy and chemotherapy. For chemotherapy, especially especially taxane-based regimens, have been associated with both transient and persistent lymph-edema [4]. Axillary surgery and/or radiotherapy are being de-escalated to reduce the risk on lymph-edema, whilst maintaining oncological control. Apart from completely omitting axillary surgery or radiotherapy, a more selective development is identification of those axillary lymph nodes that take care of drainage of the arm, by axillary reverse mapping (ARM). Recent studies indicate that when these nodes are spared from surgery [8] or radiotherapy [3, 7], the risk on lymph- edema is reduced [7]. Further prospective studies have to be carried out whether omitting surgery or radiotherapy to that region is oncological safe, and whether it indeed reduces the risk on lymph-edema. Treatment of lymph-edema The conservative treatment consists of a starting and a maintenance phase. In the starting phase reduction of the edema is the most important goal; during the maintenance phase the main goal is prevention of an increase in volume. The