**4. Conclusion**

KRAS is a very important oncogene. K-Ras protein is upregulated in different cancers and can cause bad prognosis of the disease. However, KRAS mutations are not sometimes enough to initiate cancer. Therefore, along with KRAS mutations, several environmental chemicals and drugs may contribute to the cascade of events leading to cancer.

It can be stated that in CRCs, PC, and lung cancer, KRAS mutations should be evaluated in clinics. On the other hand, the exposures of different environmental

**7**

**Author details**

Pinar Erkekoglu

Turkey

provided the original work is properly cited.

\*Address all correspondence to: erkekp@yahoo.com

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

Department of Toxicology, Faculty of Pharmacy, Hacettepe University, Ankara,

*Introductory Chapter: Interactions between Environmental Chemicals and KRAS Oncogene…*

chemicals and drugs (pesticides, PCBs, tobacco smoke, alcohol, N-nitrosamines, benzene, antidiabetics, calcium channel blockers, etc.) should be evaluated along with KRAS mutations, and the patients with preneoplastic lesions should be warned about such exposures. As KRAS gene mutations generally indicate a poor prognosis and are associated with resistance to several cancer treatments, new drugs targeting different molecules in KRAS triggering pathways should be developed in order to

overcome this resistance, particularly in CRCs, PC, and lung cancer.

*DOI: http://dx.doi.org/10.5772/intechopen.82459*

*Introductory Chapter: Interactions between Environmental Chemicals and KRAS Oncogene… DOI: http://dx.doi.org/10.5772/intechopen.82459*

chemicals and drugs (pesticides, PCBs, tobacco smoke, alcohol, N-nitrosamines, benzene, antidiabetics, calcium channel blockers, etc.) should be evaluated along with KRAS mutations, and the patients with preneoplastic lesions should be warned about such exposures. As KRAS gene mutations generally indicate a poor prognosis and are associated with resistance to several cancer treatments, new drugs targeting different molecules in KRAS triggering pathways should be developed in order to overcome this resistance, particularly in CRCs, PC, and lung cancer.
