Not all 2 gray radiation prescriptions are equivalent: Cytotoxic effect depends on delivery sequences of partial fractionated doses

Use of cetuximab in combination with pulsed reduced dose-rate radiotherapy in a patient with recurrence of nasopharyngeal carcinoma in the neck

“…The mechanism by which PRDR kills tumor cells may be low dose hyperradiosensitivity (LDHRS). LDHRS, which is increased radiosensitivity to doses <0.3-0.5 Gy, has been demonstrated in numerous tumor cells (12,13). On the other hand, the reduced dose-rate and a fixed time interval reduce toxicity and improve the sublethal damage repair of normal tissue.…”

Pulsed Reduced Dose-rate Radiotherapy as Re-irradiation for Brain Metastasis in a Patient with Lung Squamous-celled Carcinoma

“…It may increase radiosensitivity of tumour cells and provides a fixed time interval to improve sublethal damage repair of normal tissue (10,11). Studies by Howard demonstrated that PRDR is a well tolerated and safe re-irradiation approach to treat the recurrent glioma with a palliative benefit (12).…”

Pulsed reduced dose-rate radiotherapy: a novel locoregional retreatment strategy for breast cancer recurrence in the previously irradiated chest wall, axilla, or supraclavicular region

“…LDHRS has been characterized in over 40 human cell lines [11]. Lin and Wu demonstrated a statistically significant decrease in cell survival when delivering 2 Gy in 10 subfractions of 0.2 Gy compared to a single 2 Gy fraction in HT-29 adenocarcinoma cells [23]. Furthermore, potential LDHRS was demonstrated in patients with multiple skin metastases, including metastatic breast cancer, when significant tumor growth delay was noted with an ultrafractionated regimen of 0.5 Gy three times daily compared to standard 1.5 Gy once daily (P \ 0.05) [12].…”