The interrelationship of smoking, CD4+ cell count, viral load and cancer in persons living with HIV.

BACKGROUND

It is unknown if the carcinogenic effect of smoking is influenced by CD4+ cell count and viral load in persons living with HIV.

MATERIAL AND METHODS

RESPOND participants with known smoking status were included. Poisson regression adjusting for baseline confounders investigated the interaction between current CD4+/viral load strata [good (CD4+ cell count ≥500 cells/μl and viral load <200 copies/ml], poor [CD4+ cell count ≤350 cells/μl 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).

RESULTS

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).

CONCLUSION

In the large RESPOND consortium, the impact of smoking on cancer was clear and reducing smoking rates should remain a priority. The association between current immune deficiency, virological control and cancer was similar for never smokers, current smokers and previous smokers suggesting similar carcinogenic effects of smoking regardless of CD4+ cell count and viral load.