Comprehensive CADM1 promoter methylation analysis in NSCLC and normal lung specimens

Sixty-four percentage of tumour samples tested positive at the M1 region, 47% at M5 and 74% at the M9 region, compared with 65% (M1), 23% (M5) and 46% (M9) of paired normal tissue samples. Methylation of each of these promoter regions was also detected in the majority of non-lung cancer control samples. Dense methylation, defined as methylation at ≥2 promoter regions, was detected in 66% of tumour samples compared with 38% of paired normal tissues and 67% of non-lung cancer control samples. Within the small subgroup of female patients dense methylation was found in all tumour samples but only 22% of paired normal samples. Neither methylation of individual sites nor dense methylation was correlated with disease free survival. In conclusion, CADM1 promoter methylation is a frequent event in NSCLC as well as normal lung, both of lung cancer and non-lung cancer patients. Hence, CADM1 methylation analysis is unlikely to have diagnostic value for the early detection of lung cancer in an unselected population. However, a diagnostic value for selected subjects, such as females, cannot be excluded.