Lung cancer is not an AIDS-defining illness. However, people with HIV have a greater chance of developing lung cancer than non-infected people, and as people with HIV live longer due to antiretroviral therapy, more cases of lung cancer are likely to occur in the presence of HIV infection.

A number of studies have shown that lung cancer is more common in HIV-positive patients, and that it tends to occur at a younger age. For example, American researchers reviewed cancer and HIV registers in Texas between 1990 and 1995, and found that people with HIV had a 6.5-fold greater risk of lung cancer than non-infected people and a 13.6-fold greater risk of any lung malignancy. In New York, an HIV cohort had three times the risk of lung cancer compared to the general American population (Ricaurte 2001). Further evidence of an increased risk of lung cancer among HIV-infected people was produced by a review of cancer and HIV registers in New South Wales, Australia (Grulich 1999).

These trends have also been demonstrated in American women (Phelps 2001).

There is also evidence that lung cancer is more aggressive among people with weakened immune systems. There are a number of theories to explain this observation: low numbers of natural killer cells may lead to the proliferation of abnormal cells, or abnormal growth factors may be stimulated by HIV. Regardless of the cause, studies have shown that people with HIV have a worse prognosis than non-infected people, with an average survival time of five months in HIV-positive people, and ten months in the general population (Tirelli 2001).

In the United Kingdom, the incidence of lung cancer among HIV-infected people in south-east England appears to be well above the rate for the general population when matched by age and sex (Powles 2003). Since the introduction of combination therapy, the incidence of lung cancer among HIV-infected people in England has risen significantly.

The most important risk factor for lung cancer is smoking. However, in HIV-positive people, low nadir CD4 cell count has also been identified as a risk factor in some studies (Patel 2004).

Types of lung cancer

Lung cancers are broadly divided into small cell or non-small cell cancers, with the non-small type being the most common. Non-small type cancers are divided into four groups:

• Adenocarcinoma. This occurs in the outer part of the lung and often spreads to other parts of the body.

• Bronchoalveloar-alveolar carcinoma. This occurs as a single mass or in a diffuse form.

• Squamous cell carcinoma. This occurs in the central lung, especially the central airway or 'bronchus'.

• Large cell carcinoma.

Small cell cancer is more aggressive, and readily grows and spread to other parts of the body.

Symptoms of lung cancer

Often people have no symptoms of lung cancer when diagnosed via a chest X-ray. Squamous and small cell cancers are generally associated with cough, shortness of breath, bloody sputum, chest pain and wheezing or pneumonia. Adenocarcinoma causes chest pain with breathing, coughing and shortness of breath. If the cancer has spread, symptoms may include hoarseness of the voice, difficulty in swallowing, swelling of the face, arms and neck, headaches, weakness, numbness, paralysis, bone or abdominal pain.

Treatment of lung cancer

Due to the inadequacy of current treatments and late-stage diagnosis, only about 10% of non-HIV related lung cancers are cured. The three main types of treatment are surgery, radiation therapy and chemotherapy. About half of people with lung cancer are not candidates for surgery due to the spread of the cancer.

Radiation therapy generally does not cure lung cancer. Rather, it improves and extends a person's quality of life. Chemotherapy or drug treatment is the primary treatment for small cell cancer, and may kill the cancer, particularly if it is restricted to the lung.

HIV-infection does not appear to affect survival after diagnosis with lung cancer (Powles 2003).

References

Grulich AE et al. Risk of cancer in people with AIDS 13(7):839-843, 1999.

Parker MS et al. AIDS-related bronchogenic carcinoma: fact or fiction? Chest 113(1): 154-161, 1998.

Patel P et al. Incidence of non-AIDS-defining malignancies in the HIV Outpatient Study. Eleventh Conference on Retroviruses and Opportunistic Infectrions, San Francisco, abstract 81, 2004.

Phelps R et al. Cancer incidence in women with or at risk for HIV. International Journal of Cancer 94(5): 753-757, 2001.

Powles T et al. Incidence and outcome of HIV-related lung cancer in the HAART era. Second International AIDS Society Conference on HIV Pathogenesis and Treatment, Paris (Antiviral Therapy 8:1), abstract 946, 2003.

Ricaurte JC et al. Lung cancer in HIV-infected patients: a one-year experience. International Journal of STDs and AIDS 12(2): 100-102, 2001.

Tirelli U et al. Lung carcinoma in 36 patients with human immunodeficiency virus infection. The Italian Cooperative Group on AIDS and Tumors. Cancer 88(3): 563-569, 2000.