Passage: Kaposi's sarcoma (KS) is a type of cancer that can form masses in the skin, lymph nodes, or other organs. The skin lesions are usually purple in color. They can occur singularly, in a limited area, or be widespread. It may worsen either gradually or quickly. Lesions may be flat or raised. Human herpesvirus 8 (HHV8) is found in the lesions of all those who are affected. Risk factors include poor immune function, either as a result of disease or specific medications, and chronic lymphedema.Four sub-types are described: classic, endemic, immunosuppresion therapy-related, and epidemic. Classic KS tends to affect older men, be slow growing, and affect the legs. Endemic KS occurs in young adult males in Africa and can be more aggressive. Immunosuppression therapy-related KS generally occurs in people following organ transplantation and mostly affects the skin. Epidemic KS occurs in people with AIDS and many parts of the body can be affected. The diagnosis is by tissue biopsy while the extent of disease may be determined by medical imaging.Treatment is based on the sub-type, whether the condition is localized or widespread, and the person's immune function. Localized skin lesions may be treated by surgery, injections of chemotherapy into the lesion, or radiation therapy. Widespread disease may be treated with chemotherapy or biologic therapy. In those with HIV/AIDS highly active antiretroviral therapy (HAART) prevents and often treats KS. In certain cases the addition of chemotherapy may be required. With widespread disease, death may occur.The condition is relatively common in people with HIV/AIDS and following organ transplant as of 2017. Over 35% of people with AIDS may be affected. It was first described by Moritz Kaposi in 1872. It became more widely known as one of the AIDS-defining illnesses in the 1980s. The virus associated with this cancer was discovered in 1994.

Question: In what decade did it become the AIDS defining illness?
1980s