ESTRO 36 Abstract Book

S642 ESTRO 36 2017 _______________________________________________________________________________________________

EP-1196 Possible use of genetic tests: let’s consider the opinion of patients S. Gay 1 , F. Palorini 1 , M. De Santis 2 , S. Frasca 2 , C. West 3 , T. Rattay 4 , T. Rancati 1 , R. Valdagni 2 , L. Lozza 2 1 Fondazione IRCCS Istituto Nazionale dei Tumori, Prostate Cancer Program, Milan, Italy 2 Fondazione IRCCS Istituto Nazionale dei Tumori, Radiation Oncology 1, Milan, Italy 3 University of Manchester, University of Manchester, Manchester, United Kingdom 4 Christie Hospital, Christie Hospital, Manchester, United Kingdom Purpose or Objective More than half of all women undergoing breast cancer radiotherapy (RT) are anxious about possible changes to appearance of their breast, often causing negative perception of RT. Aim of this work was to explore patients’ views on a potential predictive genetic test that should provide an individual risk probability for toxicity after RT. First, to establish, before any such test is implemented in clinical practice, if such a decision-making tool is acceptable and appropriate for breast cancer pts. Finally, to understand if it would have conditioned the decision-making process with respect the treatment choice (RT + lumpectomy vs mastectomy alone). Material and Methods 11 breast cancer pts undergone semi-structured interviews after RT completion. Interviews were conducted by a radiotherapist and a radiotherapy technician. Thematic analysis was used to analyze the transcripts and identify key themes. Coding was employed to detect common topics and identify sub-themes. Results Characteristic of the 11 pts are reported in figure. Saturation of themes was reached and 6 themes and relative sub-themes were identified. 1) Comprehension & impressions about benefits of the test: pts well understand the aim of the test, a few pts see in this test a tool for improving RT plans depending on individual predisposition to toxicity, but they do not consider it as a tool to independently choose mastectomy or RT. Nevertheless, they think that the test might make them more confident about treatment since it gives additional information. 2) Preliminary preparation to RT and its side effects: the majority of pts felt prepared to RT even if preparation does not always cancel fear. Many women consider important to have the largest and reliable information. Knowing in advance also negative experiences (about toxicity) is a plus point: women want to be aware about the path they are going to follow. 3) Side effects & hypotheses about protective factors: women propose physical/psychological conditions that would have protected them from strong morbidity, as skin color, use of cream, positive attitude, beloved people, visualization techniques. 4) Thoughts about mastectomy vs RT: mastectomy is felt as a very invasive treatment when compared to RT side effects, furthermore, RT toxicity is felt not so serious as a not suitably treated cancer. 5) Emotions: anxiety and fear are insistent feelings, but they are barely connected to genetic test’s result and to the consequent storing of genetic information. 6) Importance of Human Relationships: trust and gratitude versus Hospital/Physician are conditions often more relavant for the treatment choice than the response of a

Conclusion Despite adjuvant RNI, patients remain at risk of RNR. RNI fields can be optimized, as in our cohort 34 nodes (39%) were marginal, occurring in areas not adequately covered by the prescribed dose. However, 68% of SCF and 50% of axillary relapses were still ‘in-field’, suggesting that either our prescribed dose to these areas was not adequate to control disease, or that these patients were at a high risk of systemic relapse. Use of the RTOG atlas did not provide improved coverage. The anatomical data from this cohort will be used to generate an atlas of nodal relapse that can assist in defining optimal radiotherapy volumes for RNI. Whether inclusion of such regions will alter relapse patterns and event rates is unknown.