HTB

Elevated risk of lung cancer among people with AIDS

Svilen Konov, HIV i-Base

Lung cancer risk has been estimated to be two to seven times higher in HIV-seropositive people than in general population. [1, 2] Both prognosis and survival in this group are extremely poor. Several studies looking at the smoking habits of the HIV-seropositive individuals in the US and comparing them with the habits of the HIV-seronegative population attempted to find an explanation for the elevated risk, but the results were quite contradictory, mainly as a result of the fact that the studies included only a small number of cancer cases. [3, 4] The data regarding the relationship between the HIV-induced immunosupression (measured by CD4 count) and lung cancer are scarce. [5]

To provide a clearer picture of the situation Chatuvedi AK and colleagues from the Viral Epidemiology and Biostatistics branches of the Division of cancer epidemiology and genetics of the National Cancer Institute in Rockville (US) conducted a study using the AIDS surveillance data on 397 927 HIV-seropositive individuals. [6] That data was linked to population-based cancer registry data in six US states and five metropolitan areas. The published analysis includes the results for adolescents and adults, defined as 15 year old or older at AIDS onset (diagnosed between 1980 and 2002). Cancer cases spanning 60 months prior to and 60 months after the AIDS onset were identified via the cancer registries. Additional emphasis was put on the 4-27 month period after the AIDS onset. Pulmonary occurrences of KS and NHL and cancers with no specific International Classification of Diseases for Oncology codes (8000 to 8005) were not considered lung cancers. There were not enough data on the actual smoking behaviour of the subjects and for this reason plausible hypothetic smoking scenarios were used. In particular the models, developed by Flanders at al, were applied. [7] As the models predict lung cancer mortality, the researchers modified them to predict incidence.

The results showed that lung cancer among the people with AIDS was significantly elevated. In the 10-year period spanning (60 months before and 60 months after AIDS onset), 1489 lung cancer cases were observed. This gives a SIR (standardised incidence ratio) of 1.0 (95% CI, 0.7-1.3; n=42). Lung cancer risk was particularly high during the AIDS onset period, 6 months before to 3 months after AIDS (SIR, 10.5; 95% CI, 9.7-11.4; n=629). Interestingly enough, incidence was higher in men than in women and increased with age, although the SIRs suggest that risk relative to the general population is higher for women and in particular for younger individuals (10.4 for ages 15-29 years). Even though lung cancer risk was high for all HIV risk groups, it was especially high for the IDUs (SIR, 3.9).

Among the observed cancers the predominant type was adenocarcinoma (34%), followed by squamous cell carcinoma (20.8%), and large cell carcinoma (9.9%). The risk of all histologic subtypes was similarly elevated among PWA compared to the general population.

Cancer risk was significantly elevated in all CD4 cell categories, except among PWA with CD4 count >300 mL. Similar analyses performed for the pre-HAART and HAART eras failed to show any relationship with CD4 count in either period.

The observed cancer incidence was again significantly higher among PWA, regardless of the smoking habits. That was specifically true for the PWA in the age range of 40-49 years.

References:

  1. Engels EA, Pfeiffer RM, et al., Trends in cancer risk among people with AIDS in the United States 1980-2002; 20:1645-1654
  2. Powles T, Nelson M, Bower M. HIV-related lung cancer-a growing concern? Int J STD AIDS 2003; 14:647-651
  3. Giordano TP, Kramer JR. Does HIV infection independently increase the incidence of lung cancer? Clin Infect Dis 2005; 40:490-491
  4. Hessol NA, Seaberg EC, et al., Cancer risk among participants in the womenÂ’s interagency HIV study. J Acquir Immune Defic Syndr 2004; 36: 978-985
  5. Mbulaiteye SM, Biggar RG, et al., Immune deficiency and risk for malignancy among persons with AIDS. J Acquir Immune Defic. Syndr 2003; 32:527-533
  6. Chatuvedi AK, Pfeiffer RM, et al., Elevated risk of lung cancer among people with AIDS. AIDS 2007; 21(2):207-213 7. Flanders WD, Lally CA, et al., Lung cancer mortality in relation to age, duration of smoking, and daily cigarette consumption: results from Cancer Prevention Study II. Cancer Res 2003; 63:6556-6562

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