Low levels of ATM in breast cancer patients with clinical radiosensitivity.
OBJECTIVE
Adjuvant radiotherapy for cancer can result in severe adverse side effects for normal tissues. In this respect, individuals with anomalies of the ATM (ataxia telangiectasia) protein/gene are of particular interest as they may be at risk of both breast cancer and clinical radiosensitivity. The association of specific ATM gene mutations with these pathologies has been well documented, however, there is uncertainty regarding pathological thresholds for the ATM protein.


RESULTS
Semi-quantitative immuno-blotting provided a reliable and reproducible method to compare levels of the ATM protein for a rare cohort of 20 cancer patients selected on the basis of their severe adverse normal tissue reactions to radiotherapy. We found that 4/12 (33%) of the breast cancer patients with severe adverse normal tissue reactions following radiotherapy had ATM protein levels < 55% compared to the mean for non-reactor controls.


CONCLUSIONS
ATM mutations are generally considered low risk alleles for breast cancer and clinical radiosensitivity. From results reported here we propose a tentative ATM protein threshold of ~55% for high-risk of clinical radiosensitivity for breast cancer patients.
Fang
Zhiming
Z
Department of Radiation Oncology, St George Clinical School of Medicine University of NSW, St George Hospital, Kogarah, NSW 2217, Australia. r.clarke@unsw.edu.au.
Kozlov
Sergei
S
McKay
Michael J
MJ
Woods
Rick
R
Birrell
Geoff
G
Sprung
Carl N
CN
Murrell
Dédée F
DF
Wangoo
Kiran
K
Teng
Linda
L
Kearsley
John H
JH
Lavin
Martin F
MF
Graham
Peter H
PH
Clarke
Raymond A
RA