Variability in lymph node irradiation in patients with breast cancer-results from a multi-center survey in German-speaking countries.

PURPOSE: Lymph node irradiation in breast cancer has gained complexity due to recently published studies and technical innovations which then led to changes in international guidelines. We sought to determine real-time variability in lymph node irradiation in clinical practice in German-speaking countries. METHODS: The Department of Radiation Oncology, Technical University of Munich (TUM), developed an online-based questionnaire focusing on the indication, target definition, and treatment technique of lymph node irradiation in patients with breast cancer. The invitation to participate in the survey was sent to members of the German Society of Radiation Oncology (DEGRO) by e­mail. The results of the survey were exported from the online platform into SPSS for a detailed analysis. RESULTS: In total, 100 physicians completed the questionnaire between 05/2019 and 06/2019. Despite the existence of several treatment and contouring guidelines, we observed large variability of lymph node irradiation: The guideline recommendation for internal mammary irradiation is not consistently implemented in clinical practice and irradiation of the axilla after positive SLNB (sentinel lymph node biopsy) or ALND (axillary lymph node dissection) is handled very differently. Furthermore, in most clinics, the ESTRO (European Society for Therapeutic Radiology and Oncology) contouring consensus is not used, and PTV (planning target volume) definitions and margins vary considerably. CONCLUSION: Further clinical studies should be performed with a particular focus on radiotherapy for lymphatic drainage to support and amend the existing guidelines. These studies should establish a more standardized treatment of the lymph node regions in clinical practice. Quality assurance should enforce broad implementation of consensus recommendations.

Impact of 68Ga-PSMA-PET imaging on target volume definition and guidelines in radiation oncology - a patterns of failure analysis in patients with primary diagnosis of prostate cancer.

BACKGROUND: 68Ga-PSMA-PET-imaging has proven to be a highly sensitive and specific diagnostic element for patients with prostate cancer (PC). Does the standard clinical target volume (CTV) cover the majority of 68Ga-PSMA-PET detected lymph nodes (LNs) in a primary setting? METHODS: 25 out of 159 patients with primary PC who underwent 68Ga-PSMA-PET-imaging were analyzed in the process of this study. These 25 high-risk patients had a total of 126 LNs with positive 68Ga-PSMA-ligand uptake. A standard CTV according to the 'Radiation Therapy Oncology Group' consensus was delineated and LNs were judged whether they were in- or outside of this target volume. With a Pearson correlation we additionally evaluated whether the Gleason score, the prostate-specific antigen (PSA) value or the risk according to the Roach formula correlate with a higher chance of LNs being outside of the CTV in uncommon LN locations. RESULTS: 81 (64.3%) of 126 LNs were covered by the CTV with a complete coverage of all positive LNs inside the respective radiation volume in 11 of 25 patients (44%). LNs that were not covered by the CTV included (para-aortic,) common-iliac, pre-sacral, obturatoric, para-rectal, para-vesical and pre-acetabular locations. In a statistical analysis neither the Gleason score, nor the PSA value, nor the calculated risk with the Roach formula correlated with LNs being inside or outside of the CTV in this patient group. CONCLUSION: 68Ga-PSMA-PET-imaging proves to be a valuable asset for patients and physicians for primary diagnosis and treatment planning. In our study, trusting the RTOG consensus for CTV delineation would have led to up to 35.7% of all LNs not to be included in the clinical radiation volume, which might have resulted in insufficient radiation dose coverage.

Helical TomoTherapy for locally advanced or recurrent breast cancer.

PURPOSE: We report our experience of using helical tomotherapy (HT) to treat large and irregular shaped loco-regional advanced breast cancer target volumes embracing various organs at risk. PATIENTS AND METHODS: We retrospectively analyzed 26 patients treated for very large, irregular shaped breast cancers. Patients were treated either with the intent to achieve local control in a primary setting (n = 14) or in a reirradiation setting (n = 12). The recurrence group was heavily pretreated with systemic therapy. Tumors were characterized by wide infiltration of the skin, encompassing mostly a complete hemithorax. The primary group underwent irradiation of supraclavicular, infraclavicular, axillary and parasternal lymphonodal region. Radiotherapy was combined with chemotherapy (n = 11). We assessed the PTV volume and its craniocaudal extension, the dose to the organs at risk, acute toxicity and survival. RESULTS: Median PTV was 2276 cm3 (1476-6837 cm3) with a median cranio-caudal extension of 28 cm (15-52 cm). The median dose to PTV was 40 Gy (32-60Gy). HT could be carried out in all patients without interruption. The acute toxicities were mild to moderate. The median LRFS and OS after radiotherapy was 21 and 57 months for the primary group versus 10 and 11 months for the recurrence group. Median PFS was 18 months (primary group) and 7 months (recurrence group). CONCLUSIONS: HT is feasible for advanced thorax embracing target volumes with acceptable acute toxicity. Both curative and palliative indications can be considered good indications based on treatment volume and anatomical constellation.