Two Primary Cancers to Occur in the Same Patient Colon Cancer and Small Cell Lung Cancer
I am writing about a male patient 61 years old who was diagnosed with cancer in two primary sites. The oncologist does not know how to treat this. The two sites are lung and colon (with the colon adenocarcinoma metastasized to the liver). Both lungs have been diagnosed by one pathologist as having oat cell or small cell carcinoma, but a second pathologist disputes this. If it is small cell carcinoma, the oncologist does not know how to treat it simultaneously with the colon cancer. Can you help? Also, how can we get a diagnosis, given the disagreement between two pathologists? We will be seeing another oncologist, for a second opinion.
Barbara Campling, MD, Medical Oncologist at the Abramson Cancer Center of the University of Pennsylvania, responds:
This is certainly a very complicated situation. You are wise to get a second opinion. In the case of the pathological diagnosis of small cell lung cancer, it would be worth getting a third opinion, since the two pathologists disagree. Usually small cell lung cancer is a fairly easy diagnosis for a pathologist to make. If there is difficulty in making a diagnosis it is often because the tumor tissue is not viable--so-called "crush artifact". For some reason this occurs more often in small cell lung cancer than in other tumors. It may even be necessary to get more tumor tissue in order to be sure of the diagnosis. Pathologists do not usually have difficulty in distinguishing adenocarcinoma of the colon from small cell lung cancer. Is the patient a current or former heavy smoker? Small cell lung cancer occurs almost exclusively in people who have smoked for many years. If this is not the case, the diagnosis of small cell should be questioned.
It is not that unusual for two primary cancers to occur in the same patient. Both colon cancer and small cell lung cancer are relatively common, and rarely they can be expected to occur in the same patient at the same time. Unfortunately, the treatment for each of these tumors is quite different. Do we know for sure that it is the colon cancer that has spread to the liver? It is common for colon cancer to spread to this site, but the liver is also a common site of metastasis of small cell lung cancer. The only way to know for sure would be to biopsy one of the liver metastases. Maybe this has already been done. Do we need to know? It would only be worth doing an invasive procedure such as a liver biopsy if it would affect the approach to treatment.
If the tumor in the lung is really small cell lung cancer, and if in fact both lungs are involved, then this would be considered extensive stage small cell lung cancer. Generally speaking, extensive small cell lung cancer is not a curable disease, but it usually responds, often dramatically, to chemotherapy, and survival is improved with this treatment.
If it is the colon cancer which has spread to the liver, and if this were the only problem, he would likely be treated for palliation with chemotherapy-probably a combination of 5-fluoruracil, leukovorin and irinotecan. There are occasional cases of colon cancer in which liver metastases may be operable, but this is not a consideration in this case in view of the probable lung cancer diagnosis.
The most important thing to do right now is to review the pathology of both the lung tumor and the colon cancer. If after careful review of the pathology, he proves to have small cell lung cancer affecting both lungs, as well as adenocarcinoma of the colon, the general approach is deal with the cancer that is most aggressive. Extensive stage small cell lung cancer is generally more rapidly growing and more immediately life-threatening than metastatic colon cancer. Furthermore, small cell usually responds more dramatically to chemotherapy than does colon cancer. If he were reasonably fit, most oncologist's would start a patient in this situation on chemotherapy for small cell lung cancer. The standard approach for extensive small cell lung cancer is combination chemotherapy, usually with two drugs including cisplatin or carboplatin along with either etoposide or irinotecan. If there is an excellent response to this treatment, then we would be even more sure of the diagnosis of small cell lung cancer. It would be interesting to see whether the liver metastases respond to this chemotherapy. This treatment is obviously only palliative, and both his cancers are likely to progress, even after an initial response. The chances are that the lung cancer will progress before the colon cancer.