The dosimetric impact of axillary nodes contouring variability in breast cancer radiotherapy: An AIRO multi-institutional study

Leonardi, M. C.; Pepa, M.; Luraschi, R.; Vigorito, S.; Dicuonzo, S.; Isaksson, L. J.; La Porta, M. R.; Marino, L.; Ippolito, E.; Huscher, A.; Argenone, A.; De Rose, F.; Cucciarelli, F.; De Santis, M. C.; Rossi, F.; Prisco, A.; Guarnaccia, R.; Tabarelli de Fatis, P.; Palumbo, I.; Colangione, S. P.; Mormile, M.; Ravo, V.; Fozza, A.; Aristei, C.; Orecchia, R.; Cattani, F.; Jereczek-Fossa, B. A.; Leonardi, C.; Gugliandolo, S. G.; Morra, A.; Gerardi, M. A.; Zerella, M. A.; Rosa La Porta, M.; Cante, D.; Petrucci, E.; Borzi, G.; Marrocco, M.; Chieregato, M.; Iadanza, L.; Lobefalo, F.; Valenti, M.; Carmen De Santis, M.; Cavallo, A.; Russo, S.; Guernieri, M.; Malatesta, T.; Meaglia, I.; Liotta, M.; Marcantonini, M.; Pia Colangione, S.; Mezzenga, E.; Falivene, S.; Arrichiello, C.; Barbero, M. P.; Ivaldi, G. B.; Catalano, G.; Vidali, C.; Giannittb, C.; Ciardo, D.; Ciabattoni, A.; Meattini, I.

doi:10.1016/j.radonc.2022.01.004

Aim: To quantify the dosimetric impact of contouring variability of axillary lymph nodes (L2, L3, L4) in breast cancer (BC) locoregional radiotherapy (RT). Materials and methods: 18 RT centres were asked to plan a locoregional treatment on their own planning target volume (single centre, SC-PTV) which was created by applying their institutional margins to the clinical target volume of the axillary nodes of three BC patients (P1, P2, P3) previously delineated (SC-CTV). The gold standard CTVs (GS-CTVs) of P1, P2 and P3 were developed by BC experts’ consensus and validated with STAPLE algorithm. For each participating centre, the GS-PTV of each patient was created by applying the same margins as those used for the SC-CTV to SC-PTV expansion and replaced the SC-PTV in the treatment plan. Datasets were imported into MIM v6.1.7 [MIM Software Inc.], where dose-volume histograms (DVHs) were extracted and differences were analysed. Results: 17/18 centres used intensity-modulated RT (IMRT). The CTV to PTV margins ranged from 0 to 10 mm (median 5 mm). No correlation was observed between GS-CTV coverage by 95% isodose and GS-PTV margins width. Doses delivered to 98% (D98) and 95% (D95) of GS-CTVs were significantly lower than those delivered to the SC-CTVs. No significant difference between SC-CTV and GS-CTV was observed in maximum dose (D2), always under 110%. Mean dose ≥99% of the SC-CTVs and GS-CTVs was satisfied in 84% and 50%, respectively. In less than one half of plans, GS-CTV V95% was above 90%. Breaking down the GS-CTV into the three nodal levels (L2, L3 and L4), L4 had the lowest probability to be covered by the 95% isodose. Conclusions: Overall, GS-CTV resulted worse coverage, especially for L4. IMRT was largely used and CTV-to-PTV margins did not compensate for contouring issues. The results highlighted the need for delineation training and standardization.

The dosimetric impact of axillary nodes contouring variability in breast cancer radiotherapy: An AIRO multi-institutional study / Leonardi M.C.; Pepa M.; Luraschi R.; Vigorito S.; Dicuonzo S.; Isaksson L.J.; La Porta M.R.; Marino L.; Ippolito E.; Huscher A.; Argenone A.; De Rose F.; Cucciarelli F.; De Santis M.C.; Rossi F.; Prisco A.; Guarnaccia R.; Tabarelli de Fatis P.; Palumbo I.; Colangione S.P.; Mormile M.; Ravo V.; Fozza A.; Aristei C.; Orecchia R.; Cattani F.; Jereczek-Fossa B.A.; Leonardi C.; Gugliandolo S.G.; Morra A.; Gerardi M.A.; Zerella M.A.; Rosa La Porta M.; Cante D.; Petrucci E.; Borzi G.; Marrocco M.; Chieregato M.; Iadanza L.; Lobefalo F.; Valenti M.; Carmen De Santis M.; Cavallo A.; Russo S.; Guernieri M.; Malatesta T.; Meaglia I.; Liotta M.; Marcantonini M.; Pia Colangione S.; Mezzenga E.; Falivene S.; Arrichiello C.; Barbero M.P.; Ivaldi G.B.; Catalano G.; Vidali C.; Giannittb C.; Ciardo D.; Ciabattoni A.; Meattini I.. - In: RADIOTHERAPY AND ONCOLOGY. - ISSN 0167-8140. - ELETTRONICO. - 168:(2022), pp. 113-120. [10.1016/j.radonc.2022.01.004]