Gamma radiation-induced apoptosis, G2 delay, and the risk of salivary and thyroid carcinomas--a preliminary report.
BACKGROUND
While radiation has been the only well-established risk factor for salivary and thyroid cancers, the exact mechanisms remain unknown. We hypothesized that individuals with altered apoptotic response to gamma irradiation may be susceptible to salivary and thyroid cancers.


METHODS
We tested our hypothesis in a pilot case-control study of 29 patients with neoplasms of the salivary and thyroid glands and 29 cancer-free control subjects. Patients and control subjects were matched on age, sex, and ethnicity. In vitro gamma radiation-induced apoptosis in lymphocytes was quantified utilizing the TUNEL assay and flow cytometry.


RESULTS
The mean apoptotic capacity was 13.55 +/- 10.54 for control subjects, 5.75 +/- 4.96 for patients with salivary gland carcinomas (p =.003), and 6.87 +/- 4.45 for patients with thyroid carcinomas (p =.006). These differences were associated with a 10-fold increased risk of salivary gland carcinoma (odds ratio [OR] = 10.71; 95% confidence interval [CI], 1.21-94.86) and a four-fold increased risk of thyroid carcinoma (OR = 3.93; 95% CI, 0.90-17.08).


CONCLUSIONS
Our data suggests that gamma radiation-induced apoptosis may serve as a biomarker of genetic susceptibility to salivary and thyroid carcinoma, and further confirmatory studies with larger sample size are warranted.
Zheng
Rong
R
The Department of Head and Neck Surgery, Unit 441, The University of Texas M. D. Anderson Cancer Center, Houston, TX, USA.
Dahlstrom
Kristina R
KR
Wei
Qingyi
Q
Sturgis
Erich M
EM
D000328:Adult; D017209:Apoptosis / Q000528:radiation effects*; D016022:Case-Control Studies; D005260:Female; D016195:G2 Phase / Q000528:radiation effects*; D005720:Gamma Rays / Q000009:adverse effects*; D020022:Genetic Predisposition to Disease; D006801:Humans; D020287:In Situ Nick-End Labeling; D008214:Lymphocytes / Q000528:radiation effects; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012468:Salivary Gland Neoplasms / Q000453:epidemiology / Q000235:genetics / Q000503:physiopathology*; D013964:Thyroid Neoplasms / Q000453:epidemiology / Q000235:genetics / Q000503:physiopathology*