Top Line: The Wake Forest team is at it again providing practical considerations for various fractionation schemes to safely maximize lung tumor control probability.
The Study: Here they take it even farther with histology-driven optimal fractionation schemes using HyTEC tumor control probabilities for a pooled cohort of 8510 cT1-2 non-small cell lung cancers (NSCLC). An important take away, as we’ve seen before, is that squamous cell carcinoma appears to require higher doses than does adenocarcinoma. Table 1 provides ideal doses to achieve tumor control at both isocenter (i.e., hotspot) and the periphery (i.e., minimum target dose or what many refer to as prescription dose) fractionated over 1-30 treatments for adeno versus squam. For example, the ideal prescription (Dmax) dose over 4 fractions is >48(60) Gy for adeno versus >54(67) Gy for squam. Over 8 fractions these were >58(73) Gy for adeno versus >66(82) Gy for squam. Note that all scenarios suggest an ideal hotspot of at least 125%. This would mean squams are relatively underdosed with the commonly prescribed regimens of 48 Gy / 4 and 60 Gy / 8. Practically speaking, you may want to loosen up rib and chest wall constraints and/or crank up the hot spot when treating a peripheral squam.
TBL: Histology likely needs to play a role in the calculus for how aggressively to treat early-stage NSCLC with radiation alone. | Feng, Radiother Oncol 2024
The Study: Here they take it even farther with histology-driven optimal fractionation schemes using HyTEC tumor control probabilities for a pooled cohort of 8510 cT1-2 non-small cell lung cancers (NSCLC). An important take away, as we’ve seen before, is that squamous cell carcinoma appears to require higher doses than does adenocarcinoma. Table 1 provides ideal doses to achieve tumor control at both isocenter (i.e., hotspot) and the periphery (i.e., minimum target dose or what many refer to as prescription dose) fractionated over 1-30 treatments for adeno versus squam. For example, the ideal prescription (Dmax) dose over 4 fractions is >48(60) Gy for adeno versus >54(67) Gy for squam. Over 8 fractions these were >58(73) Gy for adeno versus >66(82) Gy for squam. Note that all scenarios suggest an ideal hotspot of at least 125%. This would mean squams are relatively underdosed with the commonly prescribed regimens of 48 Gy / 4 and 60 Gy / 8. Practically speaking, you may want to loosen up rib and chest wall constraints and/or crank up the hot spot when treating a peripheral squam.
TBL: Histology likely needs to play a role in the calculus for how aggressively to treat early-stage NSCLC with radiation alone. | Feng, Radiother Oncol 2024