I would like to know if long term use of Atripla use causes cancer?

Atripla, nor any of its components (efavirenz, tenofovir and emtricitabine), have not been associated with an increase risk of developing any specific type of cancer.

On the other hand, HIV in general has been associated with an increased incidence of some malignancies. Epidemiologic studies have suggested that positive HIV patients are more likely to suffer from anal, lung, melanoma, Hodgkin's and liver cancers, among a few others. This risk appears to be high regardless if the patient takes and or responds or not to HIV medications; when compared to HIV negative individuals.

Efavirenz, one of the components of Atripla, has been associated with "teratogenicity" which in a potential for birth defects, if taken by a pregnant patient during the first trimester; but this is not cancer.

Studies using the components of Atripla for many years have fail to demontrate any increased incidence of cancer, and toxicology studies on the individual componets on Atripla have not shown an increased risk of carcinogenesis.

Other antiretrovirals (not Atripla) have been loosely associated with a potential for cancer, but this relationship has not been able to be confirmed in prospective studies.