Radiobiological rationale for compensation for gaps in radiotherapy regimes by post-gap acceleration of fractionation

British Journal of Radiology - Tập 63 Số 746 - Trang 114-119 - 1990
T E Wheldon1,2, Ann Barrett1,2
1Department of Clinical Physics and Bio-Engineering , Glasgow G11 6NT and , 11 West Graham Street, Glasgow G4 9LF
2Radiation Oncology Research Group, Beatson Oncology Centre, Western Infirmary , Glasgow G11 6NT and , 11 West Graham Street, Glasgow G4 9LF

Tóm tắt

Abstract It is now recognized that clonogenic tumour cells may repopulate vigorously during radiotherapy. Gaps in treatment schedules which lead to prolongation of overall treatment time may therefore cause sparing of tumour. Acute-responding normal tissues will also be spared if repopulation by surviving stem cells takes place. However, it is unlikely that stem cells in lateresponding normal tissues repopulate significantly over the time-scale of a conventional treatment regime; these tissues will therefore experience little or no sparing as a result of a gap. This poses a dilemma since tumour cell repopulation implies that an increased therapeutic effect in the post-gap phase of treatment may be necessary to compensate for any prolongation of treatment time, but it is difficult to achieve increased tumour effect without also increasing damage to late-responding normal tissues. Neither increased total dose nor increased fraction size is able to achieve this. A possible solution is provided if total treatment time can be held constant, with unchanged total dose and fraction size, by use of twice-daily conventionally sized dose fractions administered after the gap. Provided the twice-daily fractions are sufficiently spaced (not less than 6–8 h apart), the result will be to offset repopulation in tumour and acute-responding normal tissues without additional impairment of late-responding normal tissues. The feasibility of the approach depends on being able to complete treatment by the time originally intended; it is therefore more readily applicable to gaps occurring early rather than late in a treatment schedule. The strategy should be especially advantageous for tumours with rapid repopulative potential in sites where risk of damage to late-responding normal tissues imposes limitation of dose.

Từ khóa


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Thông tin
Thông tin xuất bản

British Journal of Radiology

Tập 63 Số 746

114-119

Thông tin tác giả