Final answer:
Viruses play a role in cancer development and increase the risk, but are rarely the sole determinant of the disease. Vaccines and a healthy immune system can help prevent certain virus-related cancers, and environmental risk factors also contribute to cancer development.
Step-by-step explanation:
While viruses may play a role in cancer development and increase a person's risk of developing cancer, they are rarely the sole determinant responsible for the disease. For example, some cancers like Kaposi's sarcoma can be controlled by a healthy immune system.
Additionally, vaccines are available for certain viruses like hepatitis B and human papillomavirus, which can help prevent these types of cancer by stimulating the immune response. Furthermore, environmental risk factors such as certain pathogens and exposure to UV radiation and air pollution also contribute to the development of cancer.