TY - JOUR
T1 - Radiobiological mechanisms of stereotactic body radiation therapy and stereotactic radiation surgery
AU - Kim, Mi Sook
AU - Kim, Wonwoo
AU - Park, In Hwan
AU - Kim, Hee Jong
AU - Lee, Eunjin
AU - Jung, Jae Hoon
AU - Cho, Lawrence Chinsoo
AU - Song, Chang W.
N1 - Publisher Copyright:
© 2015. The Korean Society for Radiation Oncology.
PY - 2015/12
Y1 - 2015/12
N2 - Despite the increasing use of stereotactic body radiation therapy (SBRT) and stereotactic radiation surgery (SRS) in recent years, the biological base of these high-dose hypo-fractionated radiotherapy modalities has been elusive. Given that most human tumors contain radioresistant hypoxic tumor cells, the radiobiological principles for the conventional multiple-fractionated radiotherapy cannot account for the high efficacy of SBRT and SRS. Recent emerging evidence strongly indicates that SBRT and SRS not only directly kill tumor cells, but also destroy the tumor vascular beds, thereby deteriorating intratumor microenvironment leading to indirect tumor cell death. Furthermore, indications are that the massive release of tumor antigens from the tumor cells directly and indirectly killed by SBRT and SRS stimulate anti-tumor immunity, thereby suppressing recurrence and metastatic tumor growth. The reoxygenation, repair, repopulation, and redistribution, which are important components in the response of tumors to conventional fractionated radiotherapy, play relatively little role in SBRT and SRS. The linear-quadratic model, which accounts for only direct cell death has been suggested to overestimate the cell death by high dose per fraction irradiation. However, the model may in some clinical cases incidentally do not overestimate total cell death because high-dose irradiation causes additional cell death through indirect mechanisms. For the improvement of the efficacy of SBRT and SRS, further investigation is warranted to gain detailed insights into the mechanisms underlying the SBRT and SRS.
AB - Despite the increasing use of stereotactic body radiation therapy (SBRT) and stereotactic radiation surgery (SRS) in recent years, the biological base of these high-dose hypo-fractionated radiotherapy modalities has been elusive. Given that most human tumors contain radioresistant hypoxic tumor cells, the radiobiological principles for the conventional multiple-fractionated radiotherapy cannot account for the high efficacy of SBRT and SRS. Recent emerging evidence strongly indicates that SBRT and SRS not only directly kill tumor cells, but also destroy the tumor vascular beds, thereby deteriorating intratumor microenvironment leading to indirect tumor cell death. Furthermore, indications are that the massive release of tumor antigens from the tumor cells directly and indirectly killed by SBRT and SRS stimulate anti-tumor immunity, thereby suppressing recurrence and metastatic tumor growth. The reoxygenation, repair, repopulation, and redistribution, which are important components in the response of tumors to conventional fractionated radiotherapy, play relatively little role in SBRT and SRS. The linear-quadratic model, which accounts for only direct cell death has been suggested to overestimate the cell death by high dose per fraction irradiation. However, the model may in some clinical cases incidentally do not overestimate total cell death because high-dose irradiation causes additional cell death through indirect mechanisms. For the improvement of the efficacy of SBRT and SRS, further investigation is warranted to gain detailed insights into the mechanisms underlying the SBRT and SRS.
KW - Radiobiology
KW - Stereotactic body radiation therapy
KW - Stereotactic radiation surgery
UR - http://www.scopus.com/inward/record.url?scp=84954451209&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84954451209&partnerID=8YFLogxK
U2 - 10.3857/roj.2015.33.4.265
DO - 10.3857/roj.2015.33.4.265
M3 - Article
C2 - 26756026
AN - SCOPUS:84954451209
SN - 2234-1900
VL - 33
SP - 265
EP - 275
JO - Radiation Oncology Journal
JF - Radiation Oncology Journal
IS - 4
ER -