Thymoma and thymic carcinomas are uncommon cancers that are often thought of as one entity, but they really warrant treatment strategies tailored to their different biology and metastatic potentials.
The integration of better diagnostic criteria, surgical techniques, and radiation therapy protocols into the treatment paradigm has begun to improve outcomes in patients with aggressive thymic malignancies, and research to identify potential candidates for targeted therapy is under way.
In an interview with Medscape, Memorial Sloan-Kettering Cancer Center's James Huang, MD (thoracic surgery service) and Gregory J. Riely, MD, PhD (thoracic oncology service) discussed some of the challenges facing clinicians who treat patients with thymic cancers and why an expert multidisciplinary team is critical to maximizing patient outcomes.
How Thymoma and Thymic Carcinoma Differ
Medscape: Let's start with the need to distinguish between thymoma and thymic carcinoma. Why is this so important?
Gregory J. Riely, MD, PhD: Patients with thymoma and thymic carcinoma have very different outcomes and responses to treatment, so making this distinction is critical.
In the past, people thought that they were closely related diseases, and maybe even that a thymoma could become a thymic carcinoma. We now have a pretty good understanding of these diseases and know that they're actually distinct entities. It's uncommon -- if not ever -- that we see a thymoma transform into a thymic carcinoma.
James Huang, MD: We know that they are morphologically and genetically different and have different biological behaviors. Thymic carcinomas tend to be much more aggressive and have a greater degree of metastatic potential and recurrence.
Because of that, they deserve to be treated differently rather than being lumped together as one rare entity that the average clinician might encounter once or twice a year.
Dr. Riely: Another important issue that comes up in making the diagnosis of thymic cancers is how you biopsy a patient with an anterior mediastinal mass. There is some dogma that patients should never have a needle biopsy that passes through the chest wall, and that every biopsy should instead be an open procedure, such as by a Chamberlain procedure.
The reason this dogma exists is twofold: One is that you can't get adequate tissue to make a diagnosis with needle biopsy, and the second is based on the theory that a biopsy that crosses the pleural space will seed the pleura, which then becomes a route of dissemination. There's no good evidence that either is true. Standard biopsy procedures -- whether Chamberlain, needle biopsy, or fine-needle biopsy -- are all perfectly reasonable to use as long as the pathologist evaluating the material has the experience to make the diagnosis.
Dr. Huang: There also used to be some confusion about whether these tumors are malignant or benign. All of these tumors (thymoma and thymic carcinoma) have malignant potential either for recurrence, local invasion, or metastasis.
Medscape Oncology © 2012 WebMD, LLC
Cite this: The Challenges of Managing Thymic Cancers - Medscape - May 11, 2012.