Neutron and photon clonogenic survival curves of two chemotherapy resistant human intermediate-grade non-Hodgkin lymphoma cell lines.
BACKGROUND
The potential role of neutron therapy in the management of intermediate-grade non-Hodgkin lymphoma (IGNHL) has not been examined because of the belief that the anticipated radiobiological effectiveness (RBE) would be uniformly very low.


OBJECTIVE
To determine the fast neutron RBE for two chemotherapy-resistant IGNHL cell lines.


METHODS
Conventional soft agar clonogenic survival curves following irradiation by 60Co and fast neutron were established for two IGNHL cell lines. These cell lines, WSU-DLCL2 and SK-DHL2B, were found in previous studies to be able to repair sublethal damage, and were also resistant to L-Pam and doxorubicin chemotherapy.


RESULTS
When the surviving fraction after 2 Gy photon was chosen as the biological endpoint, the RBE for WSU-DLCL2 and SK-DHL2B measured 3.34 and 3.06. Similarly, when 10% survival was considered, the RBE for these two cell lines measured 2.54 and 2.59. The RBE, as measured by the ratios alpha neutron/alpha photon, for WSU-DLCL2, SK-DHL2B cell lines are 6.67 and 5.65, respectively. These results indicate that the RBE for these IGNHL cell lines is higher than the average RBE for cell lines of other histological types.


CONCLUSIONS
Fast neutron irradiation may be of potential value in treating selected cases of IGNHL.
Aref
A
A
Department of Radiation Oncology and Internal Medicine, Barbara Ann Karmanos Cancer Institute and Wayne State University School of Medicine, Detroit, MI 48201, USA. arefa@karmanos.org
Yudelev
M
M
Mohammad
R
R
Choudhuri
R
R
Orton
C
C
Al-Katib
A
A
D002470:Cell Survival; D019008:Drug Resistance, Neoplasm; D005214:Fast Neutrons / Q000627:therapeutic use*; D006801:Humans; D008228:Lymphoma, Non-Hodgkin / Q000532:radiotherapy*; D017785:Photons / Q000627:therapeutic use*; D011836:Radiation Tolerance; D012062:Relative Biological Effectiveness; D014407:Tumor Cells, Cultured