Lolo

British Journal of Cancer (2008) 98, 619 – 626
& 2008 Cancer Research UK All rights reserved 0007 – 0920/08 $30.00

www.bjcancer.com

Microsatellite mutations in buccal cells are associated with aging
and head and neck carcinoma
RJC Slebos*,1,2, M Li3, S Vadivelu1, BB Burkey2, JL Netterville2, R Sinard2, J Gilbert4, B Murphy4, CH Chung1,4,
Y Shyr3 and WG Yarbrough1,2
1

Department ofCancer Biology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; 2Department of
Otolaryngology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; 3Department of Biostatistics,
Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; 4Division ofHematology/Oncology Department of
Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, TN 37232, USA

Carcinogen exposure from tobacco smoking is the major cause of upper aerodigestive tract cancer, yet heavy smokers only have
about a 10% life-time risk of developing one of these cancers. Current technologies allow only limited prediction of cancer risk andthere are no approved screening methods applicable to the general population. We developed a method to assess somatic
mutational load using small-pool PCR (SP-PCR) and analysed mutations in DNA isolated from cells obtained by mouth rinse.
Mutation levels in the hypermutable tetranucleotide marker D7S1482 were analysed in specimens from 25 head and neck squamous
carcinoma (HNSCC) cases and 31controls and tested for associations with age, smoking history and cancer status. We found a
significant association between mutation frequency and age (P ¼ 0.021, Generalized Linear Model (GLM), N ¼ 56), but no influence
of smoking history. Cases had higher mutation frequencies than controls when corrected for the effects of age, a difference that was
statistically significant in the subgroupof 10 HNSCC patients who were treated with surgery only (P ¼ 0.017, GLM, N ¼ 41). We also
present evidence that cancer status is linked to levels of nonunique, and presumably clonally derived, mutations in D7S1482. Insertion
mutations were observed in 833 (79%) of 1058 alleles, of which 457 (43%) could be explained by insertion of a single repeat unit;
deletion mutations were found in 225 (21%)of tested alleles. In conclusion, we demonstrate that the sensitive detection of single
molecule mutations in clinical specimens is feasible by SP-PCR. Our study confirms an earlier report that microsatellite mutations
increase with age and is the first to provide evidence that these mutations may be associated with cancer status in individual subjects.
British Journal of Cancer (2008) 98, 619– 626. doi:10.1038/sj.bjc.6604198 www.bjcancer.com
Published online 22 January 2008
& 2008 Cancer Research UK
Keywords: microsatellite; mutation; aging; carcinogen exposure; head and neck squamous cell carcinoma

It is estimated that exposure to tobacco carcinogens causes up to
90% of respiratory tract cancers (ACS, 2003), yet the risk of
developing a tobacco-related cancer in a lifetimesmoker is less
than 10%. Currently, the only useful measures to predict an
individual’s risk for developing lung or head and neck cancer are
based on exposure, age of the individual and, if detectable, the
presence of premalignant lesions. Given the significant role of
carcinogen exposure in these tumours, it proves difficult to study
host factors related to cancer risk (Proia et al, 2006).Such studies
are based on measurement of host DNA repair capacity, such as
the bleomycin chromosome breakage assay (Wu et al, 1998;
Rajaee-Behbahani et al, 2001), the host-cell reactivation assay
(Diem and Runger, 1997), or the comet assay (Kleinsasser
et al, 2000). These assays suggest host impairments in DNA
repair, but they have found limited application in the clinical
*Correspondence:...