Carcinogenesis: Role of viruses in carcinogenesis

1. Human papillomavirus (HPV)

   1. Sexually transmitted

      1. associated with variety of clinical diseases

         1. benign warts

         2. cervical dysplasia

         3. cervical cancer

         4. oral/laryngeal cancer

      2. over 70 types of HPV

         1. HPV 16/18—high risk types

         2. HPV 31/33—intermediate risk types

            1. Found in 85% of invasive SSCA of cervix and high grade dysplasia

         3. HPV 6/11 low risk types

            1. Found in cervical condyloma

   2. How it causes cancer

      1. integration of viral DNA into host genome important

         1. benign conditions

            1. HPV genome is maintained separate from host genome (episome)

         2. Cancer

            1. Genome is integrated into host genome

2. Epstien-Barr virus (EBV)

   1. Associated with 4 cancers

      1. Burkitt lymphoma

      2. B cell lymphoma

      3. Hodgkin’s

      4. nasopharyngeal carcinoma

3. Hepatitis B

   1. Strong association with liver cancer

   2. HBV endemic in far east and Africa

      1. these areas have highest incidence of hepatocellular carcinoma (HCC)

Category: Pathology Notes