ERBB2 and breast cancer: The effect of CK8 over-expression on survival remains controversial as in non-small cell lung carcinomas (NSCLC), increasing serum levels of CK8 were significantly associated with tumor progression and lower patient survival [126,142], whereas breast cancer patients with low expression of CK8 and high expression of Human Epidermal Growth Factor Receptor 2 (HER2) have a higher risk of recurrence and death within 5 years (Table 2) [131].