Stage Information for Kaposi Sarcoma
The staging evaluation of patients with classic Kaposi sarcoma (KS) should be individualized. The advanced age of most of the patients, localized nature of the tumor, rarity of visceral involvement, and usually indolent course of the disease should temper the extent of the evaluation. A careful examination of the skin and lymph nodes is sufficient in most cases. For the rare patient with rapidly progressive tumor or signs or symptoms of visceral involvement, appropriate evaluation is indicated. No universally accepted classification is available for epidemic KS. Staging schemes that incorporate laboratory parameters as well as clinical features have been proposed. Since most patients with epidemic KS do not die from the disease, factors besides tumor burden are apparently involved in survival.
The conventions used to stage KS and the methods used to evaluate the benefits of KS treatment continue to evolve because of changes in the treatment of human immunodeficiency virus (HIV) and in recognition of deficiencies in standard tumor assessment. The clinical course of KS, the selection of treatment, and the response to treatment are heavily influenced by the degree of underlying immune dysfunction and opportunistic infections.
The AIDS Clinical Trials Group (ACTG) Oncology Committee has published criteria for the evaluation of epidemic KS. The staging system incorporates measures of extent of disease, severity of immunodeficiency, and presence of systemic symptoms. As shown in Table 1 below, the ACTG criteria categorizes the extent of the tumor as localized or disseminated, the CD4 cell number as high or low, and a systemic illness as absent or present.
A subsequent prospective analysis of 294 patients entered on ACTG trials for KS between 1989 and 1995 showed that each of the tumor, immune system, and systemic illness variables was independently associated with survival. Multivariate analysis showed that immune system impairment was the most important single predictor of survival. In patients with relatively high CD4 counts, tumor stage was predictive. A CD4 count of 150 cells/mm³ may be a better discriminator than the published cutoff of 200 cells/mm³. A study is in progress to determine if viral load adds predictive information. None of the prior studies were conducted at a time when highly active antiretroviral therapy (HAART) was readily available. The impact of HAART on survival in KS requires continued assessment.