1. ¹International Agency for Research on Cancer, 150 cours Albert Thomas, 69372 Lyon cedex 08, France
2. ²Epidemiology and Biostatistics Unit, Aviano Cancer Center, Via Franco Gallini 2, 33081 Aviano, Italy
3. ³Coordination and Data Center, Swiss HIV Cohort Study, Mont-Paisible 16, CHUV, 1011 Lausanne, Switzerland
4. ⁴Division of Infectious Diseases, Department of Internal Medicine, University Hospital of Geneva, Rue Michel-du-Crest 24, CH-1211 Geneva 14, Switzerland
5. ⁵Division of Infectious Diseases, Department of Medicine 2, CHUV Lausanne, Lausanne 1011, Switzerland
6. ⁶Cancer Registry of the Canton of Ticino, Via in Selva 24, CH-6600 Locarno, Switzerland
7. ⁷Division of Infectious Diseases and Hospital Epidemiology, University Hospital Basel, Petersgraben 4, CH-4031 Basel, Switzerland
8. ⁸Cancer Registry of St Gallen and Appenzell, PO Box 2, CH-9007 St Gallen, Switzerland
9. ⁹Cancer Registry of Basel, Schönbeinstrasse 40, CH-4003 Basel, Switzerland
10. ¹⁰Division of Infectious Diseases and Hospital Epidemiology, Department of Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091 Zurich, Switzerland

Correspondence: Dr S Franceschi, E-mail: franceschi@iarc.fr

¹¹The members of the Swiss HIV Cohort Study are M Battegay, E Bernasconi, J Böni, HC Bucher, Ph Bürgisser, A Calmy, S Cattacin, M Cavassini, R Dubs, M Egger, L Elzi, M Fischer, M Flepp, A Fontana, P Francioli (President of the SHCS, Centre Hospitalier Universitaire Vaudois, CH-1011 Lausanne), H Furrer (Chairman of the Clinical and Laboratory Committee), C Fux, M Gorgievski, H Günthard (Chairman of the Scientific Board), H Hirsch, B Hirschel, I Hösli, Ch Kahlert, L Kaiser, U Karrer, C Kind, Th Klimkait, B Ledergerber, G Martinetti, B Martinez, N Müller, D Nadal, M Opravil, F Paccaud, G Pantaleo, A Rauch, S Regenass, M Rickenbach (Head of Data Center), C Rudin (Chairman of the Mother & Child Substudy), P Schmid, D Schultze, J Schüpbach, R Speck, P Taffé, A Telenti, A Trkola, P Vernazza, R Weber, S Yerly

Received 14 May 2008; Revised 23 June 2008; Accepted 25 June 2008; Published online 29 July 2008.

Abstract

Between 1984 and 2006, 12 959 people with HIV/AIDS (PWHA) in the Swiss HIV Cohort Study contributed a total of 73 412 person-years (py) of follow-up, 35 551 of which derived from PWHA treated with highly active antiretroviral therapy (HAART). Five hundred and ninety-seven incident Kaposi sarcoma (KS) cases were identified of whom 52 were among HAART users. Cox regression was used to estimate hazard ratios (HR) and corresponding 95% confidence intervals (CI). Kaposi sarcoma incidence fell abruptly in 1996–1998 to reach a plateau at 1.4 per 1000 py afterwards. Men having sex with men and birth in Africa or the Middle East were associated with KS in both non-users and users of HAART but the risk pattern by CD4 cell count differed. Only very low CD4 cell count (<50 cells l^-1) at enrolment or at HAART initiation were significantly associated with KS among HAART users. The HR for KS declined steeply in the first months after HAART initiation and continued to be low 7–10 years afterwards (HR, 0.06; 95% CI, 0.02–0.17). Thirty-three out of 52 (63.5%) KS cases among HAART users arose among PWHA who had stopped treatment or used HAART for less than 6 months.