Repopulation of tumor cells during fractionated radiotherapy and detection methods (Review)

Abstract

Repopulation of tumor cells during radiotherapy is believed to be a significant cause for treatment failure. The phenomenon of tumor repopulation during fractionated radiotherapy was found from clinical observations that identified that the local control rate decreased with a prolonged treatment time. A series of animal experiments with varied overall treatment time and fractionated doses were performed to demonstrate tumor cell repopulation during radiotherapy in various mouse xenograft models. However, conventional detection methods are challenging, as it is difficult to separate viable cells from those destined for apoptosis during fractionated radiotherapy. In essence, the mechanism of tumor repopulation involves the continuing proliferation of clonogenic tumor cells. In vivo imaging, tracking and targeting of the repopulation of these cells has been of clinical interest so as to administer a higher dose to the tumor repopulation regions. Currently, functional imaging methods, including 3′-deoxy-3′-18F-fluorothymidine positron emission tomography (18F-FLT PET), are showing promise in assessing the proliferation activity of tumors in vivo. This review mainly focuses on the phenomenon of tumor repopulation during radiotherapy and its conventional and novel detection methods, particularly on the feasibility of 18F-FLT PET for the detection of tumor-cell repopulation.

Therapeutic efficacy evaluation of radioimmunotherapy with 90Y‐labeled anti‐podoplanin antibody NZ‐12 for mesothelioma

“…Histological analysis showed an increase in necrotic foci and a reduced number of proliferating (Ki‐67 positive) cells in H226 tumors treated with 3.70 MBq of 90 Y‐labeled NZ‐12. These histological alterations are frequently observed in tissues damaged by radiation . Our findings suggest that 90 Y‐labeled NZ‐12 has the potential to treat malignant mesothelioma patients.…”

“…By replacing 111 In with a therapeutic radionuclide 90 Y, 3.70 MBq of 90 Y-labeled NZ-12 showed a stronger tumor growth suppression effect and prolonged survival frequently observed in tissues damaged by radiation. 40,41 Our findings suggest that 90 Y-labeled NZ-12 has the potential to treat malignant mesothelioma patients.…”

Expression of OCT4A: The First Step to the Next Stage of Urothelial Bladder Cancer Progression

“…In subsequent years, research results confirmed the presence of cells that expressed stem cell markers in other cancers [ 30 ], including brain, breast, prostate and lung tumors [ 31 , 32 , 33 , 34 , 35 ]. Cancer stem cells are relatively resistant to chemo- and radio-therapy [ 36 , 37 , 38 ], and possibly for this reason, the prognosis is poor for patients whose cancer expresses stem cell markers. Complete healing of the neoplastic process may be related to the elimination of all stem cells [ 38 ].…”

“…Cancer stem cells are relatively resistant to chemo- and radio-therapy [ 36 , 37 , 38 ], and possibly for this reason, the prognosis is poor for patients whose cancer expresses stem cell markers. Complete healing of the neoplastic process may be related to the elimination of all stem cells [ 38 ].…”

Evaluation of factors in relation with the non-compliance to curative intent radiotherapy among patients of head and neck carcinoma: A study from the Kumaon region of India

“…Sub-curative doses of radiation can result in the onset of accelerated-repopulation, and makes subsequent re-initiation of therapy difficult. [ 10 11 ] However, this is a neglected issue, and the adverse impact of non-compliance upon the cure-rates is often not provided due emphasis.…”