Basal-cell carcinoma
Basal-cell cancer is a very common skin cancer. It is much more common in fair-skinned individuals with a family history of basal-cell cancer and increases in incidence closer to the equator or at higher altitude. There are approximately 800,000 new cases yearly in the United States alone. Up to 30% of Caucasians develop basal-cell carcinomas in their lifetime. In Canada, the most common skin cancer is basal-cell carcinoma (as much as one third of all cancer diagnoses), affecting 1 in 7 individuals over a lifetime.
Basal-like carcinoma
The most common histopathological type is invasive ductal carcinoma. It can also be metaplastic carcinoma, medullary carcinoma and adenoid cystic carcinoma, with high grade, high mitosis count. Central necrosis, apoptotic cells, and stroma lymphocyte reaction and a small amount of interstitial components can be seen through microscopic examination. In BLBC, p53 mutations are usually found and the expression epidermal growth factor receptor (EGFR or HER-1) and c-kit are usually positive. Through the genetic hybridization techniques, BLBC is verified to have the most complex gene phenotypes. The relationship between BLBC and familial BRCA1-associated breast cancer has been discussed in recent years. Several studies have demonstrated that BRCA1-associated breast cancer is more likely to be a BLBC. However, there are few BRCA1 mutations in BLBC, indicating that it is likely to be epigenetic changes. Studies have reported that the negative regulatory factor of BRCA1 gene, ID4, is often highly expressed in BLBC suggesting that ID4 may play an important role in BLBC. Abnormal expression of other BRCA1 related proteins such as Fanconi protein, Bloom syndrome protein, Rad50 can also be the etiological mechanism of BLBC which needs further research. Although the molecular biology mechanisms for BRCA1 and BRCA2 are not understood very well, more and more evidence shows that there are abnormal BRBC1 pathway existing in BLBC.