Top Line: What are the latest guidelines for partial breast irradiation?
The Study: There’s been a lot of new PBI data over the past few years, which means it’s about time for an update of the ASTRO PBI guidelines. And these guidelines deliver with thorough discussions of patient selection, modalities, dose and fractionation, and treatment techniques. There was broad consensus that PBI is a good alternative to whole breast RT for those aged 40 and older with T1, grade 1-2, ER+ IDC and DCIS. On the other hand, PBI was strongly frowned upon for age <40, involved surgical margins, involved nodes, BRCA mutations, lymphovascular invasion, or lobular histology. What’s conspicuously missing is any commentary on margins other than “no tumor on ink” – even for DCIS. The techniques receiving strong support are 3D-conformal, IMRT, or multicatheter brachytherapy. Electron and photon IORT outside a clinical trial was not recommended. The strongly supported fractionation schemes for external beam PBI (3D or IMRT) are 30 Gy in 5 fractions delivered in nonconsecutive daily fractions or 40 Gy in 15 consecutive daily fractions. In general, the clinical target volume should be a 1 cm expansion on the tumor bed confined to breast tissue (1.5 cm can be considered for close margins <0.2 cm) and the planning target volume an additional 1 cm expansion. Finally, table 6 provides excellent bullet points on planning objectives.
TBL: PBI is an appealing and increasingly utilized option for favorable early stage breast cancer, and the latest ASTRO PBI guidelines are a great resource. | Shaitelman, Pract Radiat Oncol 2023
The Study: There’s been a lot of new PBI data over the past few years, which means it’s about time for an update of the ASTRO PBI guidelines. And these guidelines deliver with thorough discussions of patient selection, modalities, dose and fractionation, and treatment techniques. There was broad consensus that PBI is a good alternative to whole breast RT for those aged 40 and older with T1, grade 1-2, ER+ IDC and DCIS. On the other hand, PBI was strongly frowned upon for age <40, involved surgical margins, involved nodes, BRCA mutations, lymphovascular invasion, or lobular histology. What’s conspicuously missing is any commentary on margins other than “no tumor on ink” – even for DCIS. The techniques receiving strong support are 3D-conformal, IMRT, or multicatheter brachytherapy. Electron and photon IORT outside a clinical trial was not recommended. The strongly supported fractionation schemes for external beam PBI (3D or IMRT) are 30 Gy in 5 fractions delivered in nonconsecutive daily fractions or 40 Gy in 15 consecutive daily fractions. In general, the clinical target volume should be a 1 cm expansion on the tumor bed confined to breast tissue (1.5 cm can be considered for close margins <0.2 cm) and the planning target volume an additional 1 cm expansion. Finally, table 6 provides excellent bullet points on planning objectives.
TBL: PBI is an appealing and increasingly utilized option for favorable early stage breast cancer, and the latest ASTRO PBI guidelines are a great resource. | Shaitelman, Pract Radiat Oncol 2023