We’ll let rock and roll off the hook, but sex and drugs have direct links to cancer.
Practice safe sex. If you’re not practicing safe sex (by using condoms, abstinence or at least limiting your number of sexual partners), you are more likely to contract HPV and/or HIV. The links of HPV and cancer are noted above; the links of HIV include a higher risk of cancer of the anus, lung and liver.
Don’t share needles. Anyone injecting themselves with needles for illicit drug use should be considered a high risk for HIV and/or hepatitis. Sharing needles with an infected drug user can lead to those diseases. Hepatitis from IV drug use carries an increased risk of liver cancer.