Carcinogenesis may be caused by which of the following? (Select all that apply)

Carcinogenesis, the process through which normal cells transform into cancer cells, can be influenced by a variety of factors. The selection of multiple contributors in this question highlights the complex nature of cancer development.

Tobacco and alcohol are both well-established carcinogens. Tobacco contains numerous harmful chemicals that can lead to various types of cancer, particularly lung cancer, while excessive alcohol consumption has been linked to cancers of the breast, liver, and esophagus, among others. These substances work through different mechanisms, including direct DNA damage and promoting inflammation.

Additionally, viral infections are also significant contributors to carcinogenesis. Certain viruses, such as human papillomavirus (HPV), hepatitis B and C, and Epstein-Barr virus, have been shown to play a direct role in the development of specific cancers. These viruses can insert their genetic material into host cells, leading to mutations and uncontrolled cell growth.

Inherited genetic defects, involving mutations that are passed down through generations, also play a critical role in cancer risk. For instance, mutations in genes such as BRCA1 and BRCA2 are known to significantly increase the risk of breast and ovarian cancers. These inherited mutations can predispose individuals to cancer by compromising their body's ability to repair DNA damage or regulate cell division.