Ask the Experts Archive > Types of Cancer > Lung Cancers > Non Small-Cell Lung Cancer

Bronchioloalveolar carcinoma

Affiliation: Abramson Cancer Center of the University of Pennsylvania
Last Modified: May 1, 2003

Dear OncoLink "Ask The Experts,"
My father was diagnosed with bronchioloalveolar carcinoma with bone metastasis. He passed away very quickly. He was told that this type of cancer does not respond to chemotherapy. Can you tell me why this type of cancer is so unresponsive? Also, is this a rare type of lung cancer and what are thought to be the causes of this in a non-smoker?  

Barbara Campling, MD, Medical Oncologist at the Abramson Cancer Center of the University of Pennsylvania, responds:

Please accept our condolences to you and your family after your father's death. Bronchioloalveolar cancer (BAC) is a relatively uncommon lung cancer (about 3%), which is a type of "adenocarcinoma" (which as a group constitutes one of the major varieties of "non-small cell" lung cancers). The behavior of bronchioloalveolar cancer can be quite unpredictable, ranging from a slowly growing indolent but progressive tumor to a rapidly growing cancer, which can be quickly fatal. Although localized bronchioloalveolar cancers can be cured with surgery, this tumor is generally considered very difficult to treat. This is partly because it may arise in multiple locations within the lung. Many oncologists believe that bronchioloalveolar cancers are more resistant to chemotherapy and radiation than other types of non-small cell lung cancer. I have not been able to find any publications, which clearly show that BAC is less responsive than other forms of non-small cell lung cancer. The large published studies of chemotherapy and radiation in non-small cell lung cancer generally do not analyze response rates according to the histologic subtype, and even if they did, BAC would likely constitute such a small subgroup that it would be difficult to make comparisons. It is also said that BAC may be more responsive than other forms of non-small cell lung cancer to the investigational drug Iressa, which is being tested in clinical trials for the palliation of metastatic lung cancer, but again I have not been able to find a publication to support this claim. Although Iressa may improve symptoms in a proportion of patients with non-small cell lung cancer, it does not appear to improve survival. At the moment this drug is not available outside of a clinical trial.

Why would one type of lung cancer be less responsive than other varieties? There are a number of mechanisms by which tumor cells can resist the effects of drugs and radiation. A few examples include the increased expression of certain membrane proteins which actively export chemotherapy drugs out of cells, increased detoxification of drugs, decreased expression of the drug target, or increased repair of drug or radiation-induced damage. The cause of BAC is not known, but unlike most other forms of lung cancer, it is not consistently associated with smoking. There is a type of lung cancer that occurs in sheep (called Jaagsiekte, or ovine pulmonary adenocarcinoma), which looks very much like human BAC under the microscope. This peculiar disease of sheep is known to be caused by a virus. However, there is no definite evidence that human BAC is caused by a virus, and there is no evidence that it is contagious.

In your father's case, the cancer had already spread to bone at the time of diagnosis. Chemotherapy is often used in the management of metastatic non-small cell lung cancer, and although it is not curative treatment, in some cases it may make patients feel better, and live a little bit longer than they would without treatment. Nevertheless, response rates to chemotherapy in metastatic non-small cell lung cancer are not very gratifying, probably less than 30%. Furthermore, in patients who are very sick, chemotherapy has not been shown to be beneficial, and can actually make them sicker. This is may have been a consideration in why your dad's physician did not recommend chemotherapy.