The interrelationship of smoking, CD4+ cell count, viral load and cancer in persons living with HIV. AIDS
Mocroft et al. on behalf of the RESPOND study group aimed to investigate whether the impact of smoking on development of cancer is similar for those with different combinations of CD4+ and viral load, reflecting both viral suppression and immune dysfunction.
RESPOND participants with known smoking status were included. Statistical models investigated the interaction between current CD4+/viral load strata [good (CD4+ cell count ≥500 cells/ml and viral load <200 copies/ml], poor [CD41 cell count ≤350 cells/ml and viral load >200 copies/ml] and intermediate [all other combinations]), smoking status and all cancers, non-AIDS defining cancers (NADCs), smoking-related cancers (SRCs) and infection-related cancers (IRCs).
Out of 19’602 persons, 41.3% were never smokers, 44.4% current and 14.4% previous smokers at baseline. CD4+/viral load strata were poor in 3.4%, intermediate in 44.8% and good in 51.8%. There were 513 incident cancers; incidence rate 6.9/1000 person-years of follow-up (PYFU) [95% confidence interval (95% CI) 6.3–7.5]. Current smokers had higher incidence of all cancer (adjusted incidence rate ratio 1.45; 1.17–1.79), NADC (1.65; 1.31–2.09), SRC (2.21; 1.53–3.20) and IRC (1.38; 0.97–1.96) vs. never smokers. Those with poor CD4+/viral load had increased incidence of all cancer (5.36; 95% CI 3.71–7.75), NADC (3.14; 1.92–5.14), SRC (1.82; 0.76–4.41) and IRC (10.21; 6.06–17.20) vs. those with good CD4+/viral load. There was no evidence that the association between smoking and cancer subtypes differed depending on the CD4+/viral load strata (P>0.1, test for interaction).
In conclusion, both smoking and current CD4+/viral load strata were strongly associated with incidence of cancer, and smoking cessation should remain a priority. The association between current immune deficiency or virological control was similar for never smokers, current smokers and previous smokers suggesting similar carcinogenic effects of smoking regardless of CD4+ cell count and viral load. Reducing the burden of cancer from smoking and uncontrolled HIV infection should remain a priority for all HIV-positive individuals.