Flashback.

Ready for 5-fraction whole breast radiation? Let’s flash back to the FAST-Forward technique. The breast CTV was all parenchymal soft tissue 5 mm below the skin, excluding muscle and bone. The PTV margin was 1 cm. The planning goals were that 1) at least 95% of the PTV receives 95% of the dose, 2) max dose <110%, 3) <2% receives >107%, and 4) <5% receives >105%. Organ-at-risk goals were 1) ipsilateral lung V8Gy < 15%, 2) heart V1.5Gy < 30%, and 3) heart V7Gy < 5%. These goals were for the whole breast portion only—any additional boost dose didn’t count toward the constraints. Again, there was no clever boost scheme, so patients had to double treatment time with a whole extra week of 10 Gy in 5 fractions boost. TBL: If you’re comfortable with 15-16 fraction breast planning, there’s nothing dramatically different with this 5-fraction approach. | Brunt, Lancet 2020