BRAF and RAS mutations in human lung cancer and melanoma.

BRAF encodes a RAS-regulated kinase that mediates cell growth and malignant transformation kinase pathway activation. Recently, we have identified activating BRAF mutations in 66% of melanomas and a smaller percentage of many other human cancers. To determine whether BRAF mutations account for the MAP kinase pathway activation common in non-small cell lung carcinomas (NSCLCs) and to extend the initial findings in melanoma, we screened DNA from 179 NSCLCs and 35 melanomas for BRAF mutations (exons 11 and 15). We identified BRAF mutations in 5 NSCLCs (3%; one V599 and four non-V599) and 22 melanomas (63%; 21 V599 and 1 non-V599). Three BRAF mutations identified in this study are novel, altering residues important in AKT-mediated BRAF phosphorylation and suggesting that disruption of AKT-induced BRAF inhibition can play a role in malignant transformation. To our knowledge, this is the first report of mutations documenting this interaction in human cancers. Although >90% of BRAF mutations in melanoma involve codon 599 (57 of 60), 8 of 9 BRAF mutations reported to date in NSCLC are non-V599 (89%; P < 10(-7)), strongly suggesting that BRAF mutations in NSCLC are qualitatively different from those in melanoma; thus, there may be therapeutic differences between lung cancer and melanoma in response to RAF inhibitors. Although uncommon, BRAF mutations in human lung cancers may identify a subset of tumors sensitive to targeted therapy.

High-dose chemotherapy and stem cell support for breast cancer: where are we now?

To date, there is no definitive evidence that high-dose chemotherapy and haematopoietic stem cell support offers a survival advantage over conventional-dose chemotherapy for metastatic or high-risk primary breast cancer. Studies of metastatic disease discussed in this review have an adequate duration of follow-up given the short natural history of metastatic breast cancer. Thus, the results of these studies are unlikely to change with a longer observation period. On the other hand, studies of high-dose chemotherapy in the treatment of high-risk primary breast cancer need longer follow-up in light of the longer natural history of this type of disease. Results of unpublished studies and longer follow-up of available studies may still demonstrate a survival advantage for high-dose chemotherapy in patients with metastatic or high-risk primary breast cancer. We continue to encourage participation in innovative clinical studies.