Classical Kaposi sarcoma (cKS) is a rare complication of Kaposi sarcoma-associated herpes virus (KSHV) infection. We conducted a population-based, frequency-matched case-control study in Sicily to further investigate the reported inverse relationship between smoking and cKS and to identify other factors associated with altered risk.
All incident, histologically confirmed, cKS cases in Sicily were eligible. A two-stage cluster sample design was applied to select population controls. KSHV seropositivity was determined using 4 antibody assays (K8.1 and orf73 enzyme immunoassays and 2 immunofluroescence assays). Using SAS-callable SUDAAN we compared the characteristics of cKS cases and KSHV seropositive controls. Odds ratios (ORs) and 95% confidence intervals (CIs) are presented.
In total, 142 cKS cases and 123 KSHV seropositive controls were recruited. Current cigarette smoking was associated with reduced risk of cKS (OR 0.20, 95% CI 0.06-0.67). Edema was associated with cKS, but only when it presented on the lower extremities (OR 3.65, 95% CI 1.62-8.23). Irrespective of presentation site, diabetes and oral corticosteroid medications were associated with increased risk (ORs, 95% CIs: 4.73, 2.02-11.1 and 2.34, 1.23-4.45, respectively). Never smoking, diabetes and oral corticosteroid medication use were all independently associated with cKS risk.
We confirmed previous reports that cigarette smoking was associated with a reduced risk of cKS, and we found that risk was lowest among current smokers. We also found that cKS risk was strongly and independently associated with oral corticosteroid use and diabetes. Corroboration of these observations and investigation of possible underlying mechanisms are warranted.