 XRCC1 is over-expressed in non-small-cell lung carcinoma (NSCLC), and at an even higher level in metastatic lymph nodes of NSCLC.Deficiency in XRCC1, due to being heterozygous for a mutated XRCC1 gene coding for a truncated XRCC1 protein, suppresses tumor growth in mice.Under three experimental conditions for inducing three types of cancer (colon cancer, melanoma or breast cancer), mice heterozygous for this XRCC1 mutation had substantially lower tumor volume or number than wild type mice undergoing the same carcinogenic treatments.