[Adenocarcinoma of unknown primary site with thoracic localization and HIV: four case reports]

Epidemiology of lung cancer: Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines

BACKGROUND

Ever since a lung cancer epidemic emerged in the mid-1900 s, the epidemiology of lung cancer has been intensively investigated to characterize its causes and patterns of occurrence. This report summarizes the key findings of this research.

METHODS

A detailed literature search provided the basis for a narrative review, identifying and summarizing key reports on population patterns and factors that affect lung cancer risk.

RESULTS

Established environmental risk factors for lung cancer include smoking cigarettes and other tobacco products and exposure to secondhand tobacco smoke, occupational lung carcinogens, radiation, and indoor and outdoor air pollution. Cigarette smoking is the predominant cause of lung cancer and the leading worldwide cause of cancer death. Smoking prevalence in developing nations has increased, starting new lung cancer epidemics in these nations. A positive family history and acquired lung disease are examples of host factors that are clinically useful risk indicators. Risk prediction models based on lung cancer risk factors have been developed, but further refinement is needed to provide clinically useful risk stratification. Promising biomarkers of lung cancer risk and early detection have been identified, but none are ready for broad clinical application.

CONCLUSIONS

Almost all lung cancer deaths are caused by cigarette smoking, underscoring the need for ongoing efforts at tobacco control throughout the world. Further research is needed into the reasons underlying lung cancer disparities, the causes of lung cancer in never smokers, the potential role of HIV in lung carcinogenesis, and the development of biomarkers.

[Lung cancer in HIV-positive patients]

Since 1996, AIDS-related mortality has declined considerably with the introduction of tritherapy (HAART). This decline in mortality has been associated with an increase in the proportion of deaths caused by cancers unrelated to AIDS, particularly lung cancer. The risk of developing lung cancer is higher in the HIV-seropositive population than in the aged-matched general population, undoubtedly because of the high rate of smoking, particularly among drug abusers, but also because of other reasons which remain to be determined. Mean age at the discovery of lung cancer in HIV+ patients is 45 years, and most are symptomatic. The diagnosis is established at a locally advanced or metastatic stage in 75-90% of patients, as in the general population. Adenocarcinoma is the most common histological type. The prognosis is worse in HIV+ patients than in patients with an undetermined HIV status. Evidence on the efficacy and toxicity of chemotherapy is insufficient to draw any conclusions. Surgery remains the treatment of choice for locally advanced disease if allowed by the clinical status and respiratory function. Prospective clinical studies are needed to define a better management strategy for lung cancer in HIV-positive patients.

Lung cancer in HIV infected patients: facts, questions and challenges

AIDS related mortality has fallen sharply in industrialised countries since 1996 following the introduction of highly active antiretroviral therapy. This has been accompanied by an increase in the proportion of deaths attributable to non-AIDS defining solid tumours, especially lung cancer. The risk of developing lung cancer seems to be higher in HIV infected subjects than in the general population of the same age, partly because the former tend more frequently to be smokers and, especially, intravenous drug users. The carcinogenic role of the antiretroviral nucleoside drugs and their interaction with smoking needs to be examined. Interestingly, there is no clear relationship between the degree of immunosuppression and the risk of lung cancer, so the reason for the increased risk is unknown. The mean age of HIV infected patients at the time of lung cancer diagnosis is 45 years and most are symptomatic. Lung cancer is diagnosed when locally advanced or metastatic (stage III-IV) in 75-90% of cases, similar to patients with unknown HIV status. Adenocarcinoma is the most frequent histological type. The prognosis is worse in HIV infected patients than in the general lung cancer population. Efficacy and toxicity data for chemotherapy and radiation therapy are few and imprecise. Surgery remains the treatment of choice for localised disease in patients with adequate pulmonary function and general good health, regardless of immune status. Prospective clinical trials are needed to define the optimal detection and treatment strategies for lung cancer in HIV infected patients.

Lung cancer, a new challenge in the HIV-infected population

HIV infection predisposes patients to AIDS-defining malignancies, some of which, such as Kaposi's sarcoma and non-Hodgkin lymphoma, can affect the lungs. In 1996, AIDS-related mortality started to fall sharply in industrialized countries following the introduction of highly active antiretroviral treatments (HAART). This was accompanied by an increase in the proportion of deaths attributable to non AIDS-defining solid tumors, and especially lung cancer (LC). The increased risk of LC relative to the general population of the same age seems to be due partly to a higher prevalence of smoking among HIV-infected subjects. The average age of HIV-infected patients at LC diagnosis is about 45 years. Most patients are symptomatic at diagnosis and have only mild or moderate immunosuppression. LC is diagnosed when it is locally advanced or metastatic (stages III-IV) in 75-90% of cases, as in patients with unknown HIV serostatus. Adenocarcinoma is the most frequent histologic type. The prognosis of LC is poorer in HIV-infected patients than in the general population. Data on the efficacy and toxicity of chemotherapy in this setting are rare and rather imprecise. Surgery remains the reference treatment for localized disease in patients with adequate functional status and general health, regardless of their immune status. Prospective clinical trials are needed to define the optimal LC treatment strategies in HIV-infected patients.