Lung cancer diagnosed late in HIV-positive patients, doctors not suspecting

HIV-positive individuals have lung cancer diagnosed at a later stage, and therefore shorter survival than HIV-negative patients with lung cancer, US investigators have established in a study published in the September edition of the Journal of Acquired Immune Deficiency Syndromes. Possible reasons for delayed diagnosis identified by the researchers were an over-reliance on chest X-rays by doctors and a lack of suspicion of lung cancer.

Since the introduction of potent anti-HIV therapy, there has been a significant reduction in the incidence of the AIDS-defining cancers, Kaposi’s sarcoma and non-Hodgkin’s lymphoma, in industrialised countries. However, HIV centres in the US and Europe have reported an increase in the incidence of lung cancer compared to the early 1990s. Lung cancer still remains rare amongst individuals with HIV, and there is no suggestion or evidence that it is caused by anti-HIV therapy. As with HIV-negative individuals, cigarette smoking is the main risk factor associated with the development of lung cancer.

Nevertheless, HIV-positive patients who develop lung cancer are typically younger than HIV-negative individuals who develop the malignancy, and lung cancer tends to be diagnosed at a more advanced stage in patients with HIV, leading some clinicians to speculate that it is more aggressive in patients with HIV. What’s more, it has been shown that lung cancer often develops in HIV-positive patients when they have relatively well preserved immune function and low viral loads.

Investigators from Johns Hopkins Hospital in Baltimore conducted a retrospective study looking at diagnoses of lung cancer in patients between 1986 and 2004. They wished to determine the clinical, and demographic features of patients diagnosed with lung cancer In particular, they wished to compare survival, and the factors associated with it, between HIV-positive and HIV-negative patients. Finally, they wished to see how effectively lung cancer was diagnosed in HIV-positive patients.

In the 18 years of analysis, a total of 5,065 patients were diagnosed with lung cancer at the hospital, and of these 92 were HIV-positive. Compared to HIV-negative patients with the malignancy, those with HIV were significantly younger (p

At the time of lung cancer diagnosis, HIV-positive patients had well-controlled HIV disease with a median CD4 cell count of 305 cells/mm³ and a median viral load of 1,000 copies/ml. Almost two-thirds had taken antiretroviral therapy.

Significantly fewer HIV-positive patients than HIV-negative patients (14% versus 27%, p = 0.001) underwent surgery with the intention of curing lung cancer, but this was because surgery was not an option for many HIV-positive patients because their malignancy was so advanced at the time of its diagnosis.

Although survival after the diagnosis of lung cancer was dismal for both HIV-positive patients and HIV-negative patients, it was significantly better for HIV-negative patients, (median of nine versus six months, p = 0.002). Survival did not differ for HIV-positive patients in the eras before and after effective anti-HIV therapy became available. Of the 78 HIV-positive patients who died following a diagnosis of lung cancer, the malignancy was recorded as the cause of death in 73 cases.

In their initial analysis, the investigators calculated that mortality was 57% greater in HIV-positive patients. In multivariate analysis, the only factors significantly associated with poorer survival in HIV-positive patients were late stage of cancer diagnosis (p

The investigators then looked in detail at the medical records of 32 HIV-positive patients and their use of healthcare facilities in the year before lung cancer was diagnosed to see if doctors were using appropriate diagnostic tests and if the late detection of lung cancer could have been avoided.

Lack of access of medical facilities did not appear to be a factor in late diagnosis as the 32 patients attended the HIV clinic a median of ten times in the year before their cancer was diagnosed. Chest X-rays were performed on 30 of these patients, with 18 individuals having abnormal findings with a further nine abnormal but non-specific results. A total of 27 patients subsequently had a CT scan and in all but one instance, an abnormality thought to be cancer was detected by the scan. In addition, seven patients experienced weight loss of 10% or more in the year before their cancer was diagnosed.

“Physicians should have a high clinical suspicion of this disease in HIV-positive smokers”, recommend the investigators. Given that survival was comparable between HIV-positive and HIV-negative patients once late diagnosis was controlled for, the investigators recommend the use of CT scans on any HIV-positive smoker with a persistent chest abnormality after the use of appropriate antibiotics. They conclude, “lung cancer in the HIV-infected patient seems particularly aggressive, but early diagnosis and surgical intervention may enable longer survival.”