Molecular alterations in spontaneous sputum of cancer-free heavy smokers: results from a large screening program.
OBJECTIVE
The high mortality rate for lung cancer is likely to be reduced by the development of a panel of sensitive biological markers able to identify early-stage lung cancers or subjects at high risk. The aim of this study was to establish the frequency of K-ras and p53 mutations and p16(INK4A), RASSF1A, and NORE1A hypermethylation in sputum of a large cohort of cancer-free heavy smokers and to assess whether these markers are suitable for a routine use in the clinical practice for the early diagnosis of pulmonary cancer.


METHODS
Sputum samples were collected from 820 heavy smokers. Inclusion criteria consisted of radiologic and cytologic absence of pulmonary lesions, age at least 60 years, male gender, and a smoking history of at least 20 pack-years.


RESULTS
The analysis identified 56 individuals (6.9%) with one molecular alteration. p53 mutation and p16(INK4A), RASSF1A, and NORE1A methylation frequencies were 1.9%, 5.1%, 0.8%, and 1.0%, respectively; no K-ras mutations were found. One patient with p53 mutations was diagnosed with an early-stage lung cancer after 3-years of follow-up. The molecular analysis of bronchoscopy samples confirmed in half of the cases alterations present in sputum without revealing additional molecular changes.


CONCLUSIONS
Genetic and epigenetic abnormalities can be detected in cancer-free heavy smokers. Although the predictive value of the cancer risk is still to be established as it requires not less than 5 years of follow-up, p53 and p16(INK4A) are more promising candidates than K-ras, RASSF1A, and NORE1A for the pulmonary molecular screening of heavy smokers healthy individuals.
Baryshnikova
Ekaterina
E
Molecular Genetics Laboratory, IRCCS Istituto Clinico Humanitas, Milan, Italy.
Destro
Annarita
A
Infante
Maurizio Valentino
MV
Cavuto
Silvio
S
Cariboni
Umberto
U
Alloisio
Marco
M
Ceresoli
Giovanni Luca
GL
Lutman
Romano
R
Brambilla
Giorgio
G
Chiesa
Giuseppe
G
Ravasi
Gianni
G
Roncalli
Massimo
M
D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; D001483:Base Sequence; D001999:Bronchoscopy; D015331:Cohort Studies; D019175:DNA Methylation; D004252:DNA Mutational Analysis; D042241:Early Diagnosis; D005500:Follow-Up Studies; D019942:Genes, p16; D016158:Genes, p53; D011905:Genes, ras; D005820:Genetic Testing; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D020559:Monomeric GTP-Binding Proteins / Q000235:genetics; D011230:Precancerous Conditions / Q000235:genetics* / Q000378:metabolism; D012907:Smoking / Q000235:genetics*; D013183:Sputum / Q000166:cytology / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000235:genetics
D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; C411762:RASSF1 protein, human; C454042:RASSF5 protein, human; D025521:Tumor Suppressor Proteins; D020559:Monomeric GTP-Binding Proteins